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Background and Aims: The intercropping has great advantages in production gain, resources use and soil quality improvement. However, the effects of perennial forage legumes intercropped with annual grain crop on soil alkali-salinity was not well revealed. This study aimed to propose a spring wheat (Triticum aestivum L.)/alfalfa (Medicago sativa L.) intercropping and reveal whether this cropping system could ameliorate soil salinity. Methods: A two-year field experiment was conducted under 3 cropping systems at 3 irrigation amounts in the inland arid area of northwestern China. The cropping systems were sole spring wheat cropping (W), 12 rows spring wheat/4 rows alfalfa intercropping (W12A4) and 8 rows spring wheat/4 rows alfalfa intercropping (W8A4), and irrigation amounts included 450 (full irrigation amount, If), 360 (moderate irrigation amount, Im) and 180 mm (low irrigation amount, Il). Results: The intercropping system, especially W8A4, could more decrease soil salinity, pH and topsoil bulk density, and increase soil water content, topsoil porosity, and Ca2+ and Mg2+ contents, compared to W. Soil electrical conductivity was positively correlated with topsoil bulk density and negatively correlated with topsoil porosity, which were enhanced by intercropping and irrigation. There was weak correlation between soil electrical conductivity and soil water content. W12A4 and W8A4 led to reduction in contents of Na+, K+, Cl−, and SO42−, while Ca2+ and Mg2+ accumulated in the soil. Conclusion: Intercropped alfalfa and spring wheat could reduce soil salinity, improve soil structure and ions balance. It was recommended that W8A4 with 360 mm irrigation could be extensively used in the arid area of northwestern China, gaining grain and forage production, and helping reduce salt accumulation. [ABSTRACT FROM AUTHOR]

Aim: Assessing water consumption in intercropping systems relative to sole crop systems is important for planting system planning. Methods: This study focused on wheat/maize (Triticum aestivum L./Zea mays L.) relay intercropping to evaluate water use advantage of relay intercropping system based on the same period. Field experiments were conducted from 2014 to 2016, and three cropping patterns were designed: sole wheat, sole maize, wheat/maize intercrops. Method for evaluating water use advantage in intercropping was revised by considering water consumption of sole crops during the fallow period (periods where no plants are grown). Results: Intercropping grain yield was higher than sole cropping yield. Based on the existing method, the intercropping system had 20.4% greater water use than the sole cropping system and the water equivalent ratio (WER) was lower than 1; after revision, intercropping had 7.7% less water use than sole cropping, and the WER was greater than 1. Before revision, intercropped wheat used 3.1% more water than sole wheat, and the intercropped maize used 38.8% more water than sole maize; after revision, intercropped wheat used 24.4% less water than sole wheat, and intercropped maize used 11.0% more water than sole maize. Conclusion: These results indicated that the revised method can be better used to evaluate water use advantage of relay intercropping system. This study implied that wheat/maize intercropping increased both yield and water use based on revised method, and relay intercropping can be a suitable production practice employed in fallow policy, especially in areas with limited water. [ABSTRACT FROM AUTHOR]

Purpose: Straw incorporation is an important management practice in global agriculture. However, present straw returning usually focus on returning straw into the topsoil, while neglecting the amendment of subsoil. The study aims to investigate the effect of different straw returning strategies on soil quality and wheat productivity, and to develop recommendations regarding sustainable agriculture. Methods: A 2-year field experiment was conducted to evaluate the effects of five straw returning strategies on the soil quality and wheat yield in a winter wheat-summer maize cropping system in the North China Plain. Soil quality is defined as an index approach, including soil physical, chemical, and biological properties. The five treatments were straw removal (SR), straw mulching (SM), straw incorporation into topsoil (SI), deep-ploughing straw incorporation (DP-SI) and deep-injected straw incorporation (DI-SI). Results: Our results showed that straw returning improved soil quality across 0–40 cm depth relative to SR. The DP-SI and DI-SIa (above straw cluster) significantly increased topsoil quality by 20.5–26.2% and 13.6–19.0% compared with SI and SM. The DI-SIa also enhanced the subsoil quality, which was characterized by a significant increase in soil nutrients, compared to other straw returning strategies. The soil quality of 0–40 cm layer under DP-SI and DI-SI was significantly higher than that of other treatments. In addition, a positive correlation between soil quality and wheat yield was observed. Thus, the higher soil quality under DP-SI and DI-SI improved the average wheat yield by 9.6% and 10.7% compared with SI, respectively. Conclusion: These results indicates that DI-SI may improve subsoil properties and wheat yields and is likely an effective measure for sustainable development of a wheat-maize rotation system. [ABSTRACT FROM AUTHOR]

Background and aims: Salt stress and molecular level stresses, pose unprecedented threats to global agriculture, jeopardizing the pursuit of sustainable development goals (SDGs) related to food and nutritional security for the ever-increasing world population. These circumstances underscore the need to understand how plants respond to and interact with environmental stresses. Thus, our study focused on elucidating the role of γ-aminobutyric acid (GABA) in mitigating salt and endoplasmic reticulum (ER) stress in wheat plants. Methods: Wheat (Triticum aestivum L.) plants were exposed to salt stress [100 mM sodium chloride (NaCl)] and ER stress [5 µg mL–1 tunicamycin] applied through nutrient solution at 15 days after sowing (DAS), while 2.0 mM GABA solution was applied to leaves using a hand sprayer at 30 DAS. Growth and physiological traits measured at 45 DAS, with yield trait measurements taken at approximately 135 DAS. Results: Our findings demonstrate that GABA application reduced oxidative stress indicators by activating the ascorbate–glutathione pathway and the glyoxalase system. Moreover, GABA promoted proline metabolism, mineral nutrient accumulation, photosynthetic-affiliated source–sink traits, stomatal dynamics, nitric oxide biosynthesis, and defense- metabolites production in wheat plants under salt and ER stress. Conclusion: Overall, GABA application helped safeguard growth and yield responses in stressed plants, reversing the growth, physiological, and yield inhibition caused by salt and ER stresses. Thus, GABA may emerge as a pivotal strategy for mitigating the adverse impacts of salt and ER stress and developing tolerant genotypes in future studies. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the potential to enhance grain Selenium (Se) concentration in wheat through agronomic innovation practices and exploitation of existing genetic variation. Methods: Grain samples from field experiments carried out as part of the EU projects Nitrogen Use Efficiency (NUE-CROPS), Healthy Minor Cereals (HMC) and Quality Low Input Food (QLIF) were analysed to identify the effects of wheat species/variety, fertiliser type and crop protection regime on grain yield, grain protein and selenium concentrations. Results: Fertiliser type significantly affected grain Se concentration. In the NUE-CROPS and QLIF trials the use of farm-yard manure (FYM) resulted in significantly higher grain Se concentration when compared with mineral fertiliser applied at the same N input level. Similarly, in the HMC trial, FYM and cattle slurry resulted in a significantly higher grain Se concentration compared with biogas digestate and mineral fertiliser. In the QLIF trials, organic crop protection resulted in significantly higher grain Se concentration when compared with conventional crop protection. The NUE-CROPS and HMC trials detected significant differences between varieties of both common wheat (Triticum aestivum) and spelt (T. spelta). Correlation analyses across the trials identified a negative correlation between yield and grain Se concentration for spelt and positive correlation between plant height and Se concentration for both species. Conclusions: Higher Se concentrations in the taller spelt varieties suggest that there is considerable potential to breed/select for high grain Se by exploiting traits/genetic variation present in older, traditional wheat species (e.g. spelt). [ABSTRACT FROM AUTHOR]

Background and aims: Supporting arbuscular mycorrhizal (AM) nutrient acquisition in crops may reduce the need for fertilizer inputs, leading to more cost effective and sustainable crop production. In wheat, AM fungal responsiveness and benefits of symbiosis vary among varieties. This study explored the role of soil compaction in this variation. Methods: We examined in a field experiment how soil compaction affects AM fungal colonization and biomass in five spring wheat varieties, and how these varieties differ in their AM-mediated phosphorus (P) uptake. We also studied soil properties, and AM fungal community composition in roots and soil. Results: Soil compaction increased AM fungal colonization in the variety Alderon, characterized by root traits that indicate inefficient P uptake. Wheat P concentration and P:N ratio in Alderon and Diskett increased with increased root AM fungal colonization and biomass. In Diskett, which is the most cultivated spring wheat variety in Sweden and has intermediate root traits, total P content per m2 also increased with root AM fungal colonization and biomass. Conclusions: Some wheat varieties, potentially those characterized by P inefficient root traits, such as Alderon, may depend more on AM-mediated P uptake in compacted than in non-compacted soil. Increased P uptake with increased AM fungal colonization in Diskett suggests that efficient root and AM-mediated nutrient uptake can occur simultaneously in a modern variety. Breeding varieties that use roots and AM symbiosis as complementary strategies for nutrient uptake could improve nutrient uptake efficiency and help farmers achieve stable yields in varying conditions. [ABSTRACT FROM AUTHOR]

Background and aims: Wheat growth and productivity need an exceptional approach to resist the deleterious effects of salt stress. Methods: This study proposed to assess the effectiveness of the exogenous application of plant growth-promoting rhizobacteria (PGPR; i.e., Azospirillum lipoferum SP2, Bacillus coagulans NCAIM B.01123, Bacillus circulance NCAIM B.02324, and Bacillus subtilis MF497446) at a rate of 950 g ha−1 and foliar application of zinc oxide nanoparticles (ZnO-NPs; 500 mg L−1) against irrigation with saline (from a groundwater well) and fresh water (from the Nile River water) of wheat (Triticum aestivum L.) in sodic-saline soil during 2021 and 2022 growing seasons under open field conditions. Results: The integrated application of PGPR and ZnO-NPs protected wheat plants against irrigation with saline water through increasing antioxidant enzyme activities, i.e., catalase (47%), peroxidase (102%), and superoxide dismutase (106%), and K+ uptake (27%) over control. Conversely, higher stress mitigation through the integrated application was illustrated by a considerable decline in electrolyte leakage (−62%), proline (−39%), MDA (−56%), and H2O2 levels (−60%). The N uptake by wheat grains increased by 57% upon treating plants with PGPR+ZnO-NPs, which also increased the Zn contents in grain and straw by 117% and 72%, respectively. Also, PGPR+ZnO-NPs increased the activity of soil urease and dehydrogenase by 80% and 232%, respectively, in plots irrigated with saline water. Conclusion: The results of the present investigation suggest the use of the integrated application of PGPR and ZnO-NPs to protect wheat plants against salinity of soil and/ or irrigation water. [ABSTRACT FROM AUTHOR]

Background: Alkaline-saline (AS) stress threats crop development and productivity. Understanding the genetic control of AS tolerance in wheat is important to produce wheat cultivars that outstand such a severe stress condition. Methods: A set of 48 cultivars were tested under controlled and AS stress conditions at seedling and maturity stages. The effect of AS on seedlings and kernel traits was measured to select tolerant and high-yielding genotypes. Single-marker-analysis (SMA) and gene enrichment were conducted to understand the genetic control of AS tolerance in both growth stages. Results: AS stress decreased all kernel traits and most of the seedling traits. High correlations were found between the studied traits in each growth stage. The correlation between the traits related to both stages was non-significant. SMA identified a total of 292 and 52 markers significantly associated with the studied traits under controlled and AS stress conditions. Seven and 20 gene models were identified to control AS tolerance in each stage. Gene enrichment analysis identified one and six networks that control AS tolerance. Four genotypes were selected as superior genotypes. Conclusion: The genetic control of the studied traits differs under control and AS conditions. Two genetic systems control AS tolerance in each growth stage. This study is the first one that unlocked the genetic control of AS tolerance in seedling and mature growth stages and identified the biological process that lead to this tolerance. Four genotypes were selected for crossing in future breeding programs to improve AS tolerance in spring wheat. [ABSTRACT FROM AUTHOR]

Background and Aims: Phosphorus (P) deficiency is present in 70% of the world's arable land, and severely affects crop growth and productivity. In this study, the ameliorative effects of P-solubilizing Bacillus altitudinis WR10 on P deficiency in wheat were investigated and the underlying mechanisms were explored. Methods: Wheat was grown in half-strength Hoagland solution with KH2PO4 or Ca3(PO4)2 with or without WR10 inoculation for 14 days. Wheat biomass, root system architecture (RSA), and tissue P content were determined to evaluate the potential for alleviating P deficiency. To elucidate the underlying mechanisms, the ability of WR10 to produce organic acids (OAs), and its effects on root exudates and the ascorbic acid-glutathione (ASA-GSH) cycle in wheat were investigated. Results: WR10 significantly increased plant biomass and tissue P content, decreased the root/shoot ratio, and remodeled the RSA, predominantly by augmenting root diameter in P-deficient wheat. Under P deficiency, WR10 produced up to 72 OAs, including palmitic, fumaric, methylmalonic, elaidic, benzoic, and nonanoic acids, decreased pH of the culture solution, and increased soluble P content. Our split-root experiment and non-targeted metabolomics revealed that WR10 inoculation reprogrammed root exudated in P-deficient plants, which enhanced the contents of (−)-threo-isodihomocitric, (R)-2-ethylmalic, 4Z,7Z,10Z,13Z-hexadecatetraenoic, and colnelenic acids. In addition, WR10 significantly upregulated APX, MDHAR, DHAR, GR, and GS gene expression levels and increased the ASA and GSH contents involved in the ASA-GSH cycle, thereby decreasing H2O2 levels. Conclusion: B. altitudinis WR10 alleviates P deficiency in wheat by remodeling the RSA, improving P availability, and activating the ASA-GSH cycle. [ABSTRACT FROM AUTHOR]

Background: Zinc (Zn) enrichment in cereal grains is a promising method to relieve human Zn malnutrition. Many factors influence grain Zn accumulation, but the role of rhizosphere microbes in soil environment and crop Zn uptake remain unknown. Methods: This study examined the relationships between rhizosphere microbes, rhizosphere soil nutrients, vegetal and grain Zn concentrations in six wheat (Triticum aestivum L.) cultivars with contrasting grain Zn concentrations grown in Zn-deficient soil. Results: Roots and spikes Zn concentrations at anthesis were positively correlated with grain Zn concentrations. Root Zn concentration was negatively correlated with rhizosphere soil available phosphorus (AP) and Zn (AZn). Spike Zn concentration was positively correlated with rhizosphere ammonium-N. The bacterial community assembly was more profoundly dominated by stochastic processes in the rhizosphere of high-Zn cultivars. Specifically enriched microbes were found within 144 amplicon sequence variants (ASVs) affiliated with 15 phyla in the rhizosphere of the high-Zn cultivars at anthesis. Enriched microbes significantly correlated with AZn were only identified in the rhizosphere of high-Zn cultivars, where g_Olivibacter and o_Microtrichales had the function of decomposing organic matter, potentially facilitating the formation of organic acids and dissolving soil Zn. The AP-related enriched microbes g_Lysobacter, g_Crossiella, and g_TM7a in the rhizosphere of high-Zn cultivars were significantly negatively correlated with AP, indicating their role in decreasing the AP. Conclusion: This study implied that the rhizospheric microbes in the high-Zn cultivars had the potential function of increasing soil Zn availability and decreasing soil P availability, as an important microbial strategy for wheat grain Zn biofortification. [ABSTRACT FROM AUTHOR]

Background and aims: Soil carbon sequestration can play an important role in mitigating climate change. Higher organic C inputs to agricultural soils are needed in order to increase soil organic carbon (SOC) stocks. Genotype selection and breeding towards increased root biomass may enhance root C inputs to the soil and could therefore be a promising, easy-to-implement management option for potentially increasing C sequestration. However, an increase in root C inputs may compromise yield, which is not desirable in terms of food security. Methods: Data from 13 global studies with field experiments were compiled in order to estimate the potential of optimised genotype selection for enhancing root biomass without compromising the yield of winter wheat, spring wheat, silage maize, winter rapeseed and sunflower. A lack of data on the effect of variety on rhizodeposition was identified which thus had to be excluded. Results: Systematic genotype selection increased mean yields by 52% and mean root biomass by 22% across all crops and sites. A median root C increase of 6.7% for spring wheat, 6.8% for winter rapeseed, 12.2% for silage maize, 21.6% for winter wheat and 26.4% for sunflower would be possible without a yield reduction. Conclusion: Overall, this review demonstrates that optimised genotype selection can be a win-win option for increasing root biomass C input to soil while maintaining or even enhancing yield. [ABSTRACT FROM AUTHOR]

Background and aims: Yield and grain quality of wheat have been negatively affected by the occurrence of blast, caused by the fungus Pyricularia oryzae, epidemics. Therefore, alternatives for blast management need to be explored and plant nutrition becomes a promising option. The hypothesis that wheat plants with higher foliar concentrations of silicon (Si) and magnesium (Mg) could have their resistance increased against blast was investigated in this study at the physiological and biochemical levels. Methods: Wheat plants were grown in nutrient solution and given the following treatments: -Si (0 mM) + Mg (0.25 mM), -Si (0 mM) + Mg (0.6 mM), + Si (2 mM) + Mg (0.25 mM), and + Si (2 mM) + Mg (0.6 mM). Plants were non-inoculated (NI) or inoculated (I) with P. oryzae and used for an in-depth analysis of their photosynthetic apparatus (determination of chlorophyll (Chl) a fluorescence parameters and pool of photosynthetic pigments) and quantification of defense-related and antioxidant enzymes activities as well as some metabolites [soluble phenolics, lignin, malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion radical (O2−)]. Results: Blast symptoms were reduced for Si-supplied plants due to higher foliar Si concentration. The Mg itself or its possible synergism with Si did not contribute to lowering blast severity even considering the greater foliar Mg concentration for plants supplied with 0.6 mM Mg compared to 0.25 mM Mg. Higher values of Chl a fluorescence parameters (variable-to-maximum chlorophyll a fluorescence ratio, photochemical yield, and yield for dissipation by down-regulation), great concentration of chlorophyll a + b, and less production of MDA, H2O2, and O2− were obtained for Si-supplied and infected plants due to reduced blast symptoms. The Si-supplied and infected plants, regardless of Mg rate, displayed higher activities of defense (chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase, peroxidase, and polyphenoloxidase) and antioxidant (ascorbate peroxidase, catalase, glutathione reductase, and superoxide dismutase) enzymes as well as more lignin concentration. Four clusters (C) [C1 (NI plants for 0.25 mM Mg -Si, 0.6 mM Mg -Si, 0.25 mM Mg + Si, and 0.6 mM Mg + Si treatments), C2 (I plants for 0.25 mM Mg -Si and 0.6 mM Mg -Si treatments), C3 (I plants for 0.25 mM Mg + Si treatment), and C4 (I plants for 0.6 mM Mg + Si treatment)] were obtained with the principal component analysis. Conclusion: No evidence of synergism between Si and Mg or a possible effect of higher foliar Mg concentration to maximize wheat resistance to blast, linked to a more robust antioxidative metabolism, was obtained. The fact that Mg could not reduce blast symptoms cannot discard its indirect effect on wheat defense reactions considering the key functions it plays in plant metabolism, especially at the photosynthetic level. [ABSTRACT FROM AUTHOR]

Background and aims: We explored how phosphorus (P) availability influences accumulation of rare earth elements (REE) in plant species with different P-acquisition strategies beyond the commonly explored REE-phosphate precipitation. Methods: Two P-efficient carboxylate-releasing lupin species (Lupinus albus, and L. cosentinii) and four species with less carboxylate release under P-deficiency (Triticum aestivum, Brassica napus, Pisum sativum, Cicer arietinum), were cultivated with a split-root system on two sand types. Phosphorus availability was controlled on one root side by watering the plants with 100 μM P or 0 μM P solutions. Carboxylate release and changes in pH were measured on both sides. Concentrations of nutrients, cadmium (Cd), aluminum (Al), light REE (LREE: La–Eu), and heavy REE (HREE: Gd–Lu, including Y) in roots and shoots were analyzed by ICP-MS. Results: P-deficient T. aestivum, B. napus and C. arietinum did not respond with elevated carboxylate release. These species accumulated more REE when the P supply was low and higher REE concentrations were proportional to declining plant growth. However, P. sativum, L. albus and L. cosentinii accumulated less REE when P supply was low. Plants that strongly acidified the rhizosphere and released low quantities of dicarboxylates accumulated more REE (with higher LREE/HREE ratios) than species that released tricarboxylates. Conclusion: Our findings suggest that REE accumulation strongly depended on rhizosphere acidification, in concert with the amount and composition of carboxylates determining the exclusion of REE-carboxylate complexes. Leaf REE signatures may offer a promising ionomics screening tool for carboxylate release into the rhizosphere. [ABSTRACT FROM AUTHOR]

Background and aims: Inappropriate irrigation and nitrogen fertilization caused high global warming potential (GWP) while reduced carbon sequestration of farmland systems in arid regions. Understanding the effects of irrigation and nitrogen fertilization on net ecosystem carbon budget (NECB) and its components are crucial to mitigate GWP and increase carbon sequestration. Methods: A field experiment was carried out to investigate the impact of irrigation and nitrogen fertilization on soil greenhouse gas (GHG) emissions, crop net primary productivity (NPP), NECB and net GWP from spring wheat farmland in arid Northwest China. Three irrigation depth levels, 180, 315, and 450 mm and three nitrogen fertilization levels, 170, 250, and 340 kg ha–1 were designed. Results: Irrigation and fertilization significantly affected GHG emissions and carbon sequestration of farmland system. Reducing irrigation depth from 450 to 315 mm reduced soil CO2 and N2O emissions but did not significantly reduce NPP. Increasing nitrogen fertilization from 170 kg ha–1 to 250 kg ha–1 improved NPP, but continuously increasing nitrogen input decreased NPP while increasing soil CO2 and N2O emissions. Therefore, the NECB first increased and then decreased, while the net GWP first decreased and then increased as the irrigation depth and nitrogen fertilization decreased. Overall, the moderate irrigation and fertilization treatment (i.e., 315 mm irrigation and 250 kg ha–1 nitrogen fertilization) obtained the highest NECB and the lowest net GWP. Conclusion: Improving irrigation and fertilization management can increase carbon sequestration and mitigate the net GWP of farmland systems by increasing crop NPP and reducing soil GHG emissions. [ABSTRACT FROM AUTHOR]

Aims: N2O emitted by agricultural ecosystems has a great impact on global warming and climate change. The use of controlled-release fertilizers (CRF) can decrease greenhouse gas emissions. However, the general patterns and variability of nitrogen functional genes in response to CRF associated with N2O emission have not been synthesized under climate change. Methods: We investigated the effects of CRF, elevated CO2 concentration (EC), elevated temperature (ET), and their combination on N2O emission, enzyme activities and gene abundances. Results: We found that the cumulative N2O emissions was in the range of 0.39–1.65 kg·ha−1 in the wheat-growing season, accounting for 0.54%–2.29% of the total nitrogen input. N2O emissions were considerably positively correlated with ammonia-oxidizing bacteria (AOB) at elongation stage. CRF inputs significantly decreased N2O emissions by 29 − 66% compared with urea due to decreased AOB abundance and inhibited nitrite reductase activities at elongation stage. EC significantly decreased N2O emissions by 30 − 50% likely resulting from the inhibition in nitrifying and denitrifying community compared with ambient CO2 concentration. ET significantly increased N2O emissions by increasing N mineralization in wheat soil under CRF due to higher NH4+-N and NO3−-N concentration in wheat soil at elongation stage. In addition, ECET had antagonistic effect on N2O emissions. CRF had no significant effect on wheat yield under climate change scenarios. Conclusions: CRF decreased the cumulative N2O emissions under climate change scenarios. This is critical for understanding the responses of N2O emissions from wheat soil under CRF to future CO2 enrichment and warming for the establishment of mitigation and adaptation policies. [ABSTRACT FROM AUTHOR]

Background: Boron (B) is a micronutrient required for optimal plant growth and development. It is primarily involved in pectin crosslinking in the rhamnogalacturonan II region to ensure cell wall integrity. In plants grown under limited soil B availability, seed yield and quality are often compromised. However, excessive B accumulation can also be toxic to plants. Therefore, plants must maintain optimal tissue concentrations of B by regulating transport processes. Scope: This article is a critical review of the molecular mechanisms involved in B transport under limited and excess B conditions. We focus on various B transport proteins and their B-dependent regulation, mainly as studied in the model plant Arabidopsis thaliana, and summarize research progress on B transport and its regulation in Brassica napus, Oryza sativa, Hordeum vulgare, Triticum aestivum, and Zea mays. Conclusion: Under limited B conditions, the nodulin 26-like intrinsic protein (NIP) AtNIP5;1 and the borate transporter (BOR) AtBOR1 mediate the radial transport of boric acid or borate from soil to the xylem. AtBOR2 also plays a role in root cell elongation by increasing the B-RGII dimerization rate. Under excess B conditions, AtBOR4 is involved in the directional export of B from roots to soil. In crop plants, NIPs and BORs responsible for B efficiency and excess B tolerance are becoming key targets of plant breeding. These B transport proteins are regulated at the transcription, mRNA degradation, translational repression, and endocytic degradation levels to maintain B homeostasis. Understanding the complex regulatory mechanisms of B transport will allow us to develop high-yielding plants under fluctuating soil B conditions. [ABSTRACT FROM AUTHOR]

Aims: A modified sowing pattern (MSP) consisting of wider seedling strips has been shown to improve the nitrogen (N) use efficiency of winter wheat by enhancing N uptake from soil. However, the effects of MSP on root size, 15N-uptake efficiency, and N uptake from different soil depths have not been yet elucidated. Methods: The seedling strip width in the MSP was 8–10 cm compared with 3–4 cm in the conventional sowing pattern, with a fixed row spacing of 27 cm. Both were used to investigate root size, root spatial distribution, and N uptake from different soil depths. Results: The increased intra-row spacing of the MSP resulted in increases in the number of tillers and roots and in dry matter per unit area. The total root weight increased due to the higher root/shoot ratio induced by the enhanced nutrient requirements. Together with the increase in root number, the greater total root weight led to increases in root length and surface area, with a constant specific root length and surface area based on the total root weight. The absolute increases in root length and surface area densities declined with soil depth. Root 15N-uptake efficiency based on root length and surface area decreased in the topsoil but increased or remained unchanged in the subsoil. Conclusions: 15N-uptake from each soil layer increased, with the largest increase occurring in the 40 to 80 cm soil layer. Due to the enhanced N uptake, particularly from the subsoil, the MSP may be used to reduce N inputs without penalizing yield. [ABSTRACT FROM AUTHOR]

Purpose: Legume crops are advocated for integration into crop rotation systems, and cereal-based rotations with the presence of legumes have a substantial effect on improving soil fertility and health. It is not yet clear whether the frequency of legume inclusion in crop rotation systems influences soil biochemical properties and soil organic matter (SOM) mineralization. Methods: An incubation experiment was conducted with 13C-glucose addition to evaluate the influences of soybean (Glycine max L.) cropping frequency on SOM mineralization under long-term wheat (Triticum aestivum L.)- and maize (Zea mays L.)-based rotation systems. Phospholipid fatty acids (PLFAs) and 13C-PLFAs were measured to explore microbial biomass, community structure and microbial utilization of glucose in wheat and maize systems. Results: Glucose addition increased native SOM mineralization, i.e. positive priming effect. Compared with less soybean cropping frequency under long-term wheat- and maize-based rotation systems, wheat-soybean-soybean-soybean rotation and maize-soybean-soybean rotation increased the total biomass (PLFAs), fungal biomass and decreased the ratio of bacteria to fungi. Furthermore, the ratio of bacteria to fungi was negatively correlated with PE intensity, indicating that greater fungal biomass played a key role in stimulating SOM priming. That the proportion of 13C-glucose in G- and fungi had a positive relationship with PE intensity also supported this conclusion. The presence of soybean in wheat- and maize-based rotations increased SOM priming, while the soybean cropping frequency had no significant influence on SOM priming. However, in contrast to a maize-based rotation system, the same frequency of soybean in a wheat-based rotation system had lower soil C/N ratio and higher B/F ratio, and resulted in lower PE intensity. Conclusions: Our findings indicated that the presence of soybean in wheat- and maize-based rotation systems increased PE intensity because of higher soil C/N ratio and lower B/F ratio, while the soybean cropping frequency had no significant influence on SOM priming. Furthermore, the presence of soybean in maize system induced more SOM priming than that in wheat system with glucose addition. [ABSTRACT FROM AUTHOR]

Purpose: The main goal of this study was to determine if ancient wheat varieties could store more carbon than modern ones in the presence or absence of inputs, due to a likely bigger and deeper root system and a slower mineralization rate. Methods: We conducted a field experiment with four modern and four ancient varieties (released before 1960 and often grown without inputs), with and without chemical inputs (nitrogen, herbicide and fungicide taken as a single factor). Root morphology was assessed by image analysis, potential catabolic activities of fructose, alanine, citric acid by MicroResp™ and overall CO2 emissions by incubating soil and roots from each modality for 60 days. Results: The breeding type did not affect root traits, substrates respiration nor CO2 emissions in our environmental conditions. The application of inputs did not affect root traits but influenced the respiration of specific substrates and CO2 emissions. The most noticeable response was due to the "breeding type x inputs" interaction: inputs increased CO2 emissions from soil and root tissues of ancient varieties by 19%, whereas no effect was observed for modern varieties. Conclusion: Taken together, our results did not support the hypothesis that ancient varieties could be more performant than modern ones in storing carbon in our experimental conditions. Increased CO2 emissions by ancient varieties in the presence of inputs showed that ancient and modern varieties differed in their phenotypic plasticity. [ABSTRACT FROM AUTHOR]

Purpose: Polyphosphate (poly-P) fertilizers were proposed to increase the low phosphorus use efficiency (PUE) of orthophosphate (ortho-P) fertilizer but empirical data is inconsistent. Our study is aimed at investigating how soil properties, application time, and growth duration affect their phyto-availability. Methods: Olsen-P dynamics were monitored using six soils amended with either ortho-P or poly-P. Subsequently, two contrasting soils (sandy and loamy) were selected to estimate P availability to plants using wheat as a model plant. Mechanistic modelling was used to interpret P dynamics in these experiments. Results: For poly-P amended soils, Olsen-P increased continuously, while using ortho-P fertilizer the highest values were attained right after application and then monotonously decreased afterward. Olsen-P dynamics varied greatly among soils depending on their sorption capacity and related properties. In sandy soils, Olsen-P was consistently higher for ortho-P. In highly calcareous soils, Olsen-P was higher for poly-P after three weeks. Plant experiments confirmed a greater uptake of poly-P over ortho-P in loamy soil and extended trials (4 months) but not in sandy soils or short-term trials (4 weeks). Geochemical modeling suggested that complexation of soil Ca by poly-P reduced long-term P immobilization. Conclusions: Soil properties and growth duration affect the efficiency of ortho-P vs. poly-P fertilizers. In clayey soils and extended growth duration, poly-P fertilizer can enhance PUE due to its prolonged phyto-availability as compared to ortho-P. In sandy soils and short growth duration poly-P has little advantage. The complexation of Ca by poly-P may have caused the increase of P phyto-availability. [ABSTRACT FROM AUTHOR]

Purpose: Uncovering potential biocontrol agents that suppress soil-borne pathogens is an important step toward developing sustainable management strategies for disease control and to maintain plant health. Plant cultivars influence rhizosphere microorganism-mediated soil-borne disease control. However, the disease-resistance mechanisms and microbial taxa involved in the control of soil-borne mosaic virus are largely unknown. Methods: We designed a field experiment on wheat cultivars for virus-resistance identification and conducted metagenomic analysis to determine the potential mechanisms used by rhizosphere microbial communities that affect the density of the mosaic virus vector-Polymyxa graminis, and to identify potential microbes that inhibit virus transmission. Results: We found high P. graminis abundance and microbial diversity in the susceptible wheat cultivar rhizosphere. The relative abundance of indicative phagotrophs showed a strong negative correlation to P. graminis abundance during disease onset, indicating that predator–prey interactions influenced P. graminis activity. Moreover, we found strong and negative associations between the relative abundance of key ecological cluster, hub phagotrophic species and P. graminis abundance in multitrophic ecological networks. A structural equation model analyses indicated that phagotrophic protists were the main predictors of P. graminis abundance upon disease onset. Conclusion: Our results demonstrate the important role of phagotrophic protists as top-down controllers for plant defense against pathogens. Our findings highlight the complexity of rhizosphere networks, reflecting the co-occurrence patterns of multi-trophic level microbes in virtual networks and strengthening the association between soil microbial diversity and plant health. [ABSTRACT FROM AUTHOR]

Background and Aims: Polyamines (PAs) play important roles in drought tolerance, but the physiological significance of putrescine (Put) conversion into other forms of PAs is not clear in filling grain embryos of wheat (Triticum aestivum L.) plants under drought stress. Methods: The changes in the levels of three main free PAs, Put, spermidine (Spd), and spermine (Spm), covalently conjugated PAs (perchloric acid-soluble), and covalently bound PAs (perchloric acid-insoluble), were investigated in embryos of filling grains, in two wheat cultivars, Longmai No. 079 (drought-tolerant) and Wanmai No. 52 (drought-sensitive). Furthermore, the activities of arginine decarboxylase, S-adenosylmethionine decarboxylase, and transglutaminase, which affect free Put biosynthesis, Spd and Spm biosynthesis from Put, and conversion of free PAs into bound PAs, respectively, were also determined. Exogenous PAs and PA biosynthesis inhibitors were also applied in the experiment. Results: Under drought stress, the levels of conjugated PAs did not significantly differ between the two cultivars. However, the levels of free Spd, free Spm and bound Put increased more markedly (p < 0.05) in drought-tolerant Longmai No. 079 than in drought-sensitive Wanmai No. 52, suggesting that free Spd and Spm, and bound Put, which were converted from free Put, were possibly involved in drought tolerance. Exogenous Spd treatment enhanced the drought-induced increases in endogenous Spd and Spm contents in drought-sensitive Wanmai No. 52, and increased drought tolerance, as judged by the decrease in flag leaf relative plasma membrane permeability and increases in flag leaf relative water content, 1000-grain weight and grain number per spike. Methylglyoxal-bis guanylhydrazone and o-phenanthrolin inhibited drought-induced increases in free Spd, Spm, and bound-Put contents in drought-tolerant Longmai No. 079, and decreased in drought tolerance. Conclusions: Collectively, the conversions of free Put into free Spd, Spm, and bound Put in filling grain embryos enhanced the tolerance of wheat plants to drought stress. [ABSTRACT FROM AUTHOR]

Aims: Rapeseed (Brassica napus L.) is an extensively used rotation crop that provides various benefits to the subsequent crops. One of these benefits is the suppression of soilborne pathogens through its release of biocidal metabolites, which, however, can also have detrimental effects on arbuscular mycorrhizal fungi (AMF). Reduction in AMF activity is associated with increased cadmium (Cd) accumulation in aboveground plant parts. We investigated the effect of rapeseed rotation on Cd concentration of the following wheat crop. Methods: Wheat plants were grown in pots treated with low, medium and high rates of phosphorus (P) as i) rapeseed-wheat and ii) wheat-wheat rotations and analyzed for Cd concentrations. An additional experiment was conducted to study the effects of the rapeseed and wheat rotations on mycorrhizal root colonization and shoot Cd of subsequent crops. Results: There was a substantial increase in shoot, spike and grain Cd concentration and content of wheat plants grown after rapeseed, compared with those grown after wheat. The differences in shoot Cd concentration and accumulation between the rapeseed-wheat and wheat-wheat rotations were minimized at the highest P-application rate, likely because the wheat plants were poorly colonized by mycorrhizal fungi. Increased shoot Cd concentrations and reduced AMF colonization in wheat plants grown after rapeseed were confirmed in an additional experiment. Conclusion: The results clearly demonstrate elevated Cd concentrations in wheat plants when cultivated in rotation with non-mycorrhizal rapeseed plants. These results also point to a potential Cd concern in crop rotation systems including non-mycorrhizal crops such as rapeseed. [ABSTRACT FROM AUTHOR]

Background: Cadmium (Cd) levels of food crops can be elevated through management activities and geogenic factors. While emphasis is placed on reducing Cd in phosphorus (P) fertilizers, increasing evidence shows that Cd accumulation in plants is markedly influenced by arbuscular mycorrhizal fungi (AMF). Mycorrhizas are highly effective in reducing shoot Cd accumulation through various mechanisms including Cd immobilization in fungal structures and increasing root zinc (Zn) uptake. Scope: The increase in plant Cd concentrations in response to short- or long-term P fertilization is not necessarily related to fertilizer Cd concentration. Novel results suggest that this counterintuitive result is related to suppressed mycorrhizal colonization by P fertilization. When applied P fertilizers reduce mycorrhizal colonization, there is risk for concurrent increased Cd accumulation in plants. Although the mechanism is not fully understood, grain Cd concentrations in crop rotations are highest in plants grown after non-mycorrhizal (e.g. rapeseed), rather than mycorrhizal species (e.g., wheat), probably due to diminished mycorrhizal activity by non-mycorrhizal plants. These findings indicate that rapeseed-wheat rotations may enhance Cd concentrations in human diets. Published data also show that AMF contribute up to 50% of total Zn uptake in plants. Conclusions: Considering various soil and crop management factors that negatively affect mycorrhizal colonization, a priority should be to maintain functional AMF in soils to support healthy food systems. Considering also the fundamental role of AMF in root Zn uptake and the global prevalence of human Zn deficiency, improving functioning of AMF may provide a dual benefit to healthy and nutritious food production. [ABSTRACT FROM AUTHOR]

Purpose: This research studies the alleviation potential of N- or/and P- deprived Coccomyxa chodatii SAG 216–2 extracts as biostimulants on mercury stress (10 and 30 mg L−1) of wheat seedlings. Materials: The study includes the interactive effect of mercury and biostimulants on growth, reactive nitrogen and oxygen species, membrane stability, and antioxidant activity in wheat seedlings. Results: The imposed toxic effects of Hg-stress on the studied parameters were to a great extent less noticeable under different algal extracts, and the magnitude of augmentation was P-deprived extract > P-&N-deprived extract > N-deprived extract > Normal algal extract. Higher Hg-tolerance modulated by algal extracts, especially P-deprived extract, was associated with high antioxidant capacity and ferric reducing power. These activities could instigate the antioxidant system (enzymatic and non-enzymatic) under Hg-stress. Furthermore, the algal extracts broadly alleviated wheat chelating mechanism deterioration by Hg-stress via enhancing phytochelatins, reduced glutathione, and metallothioneins. Thus, the applied algal extracts retarded Hg accumulation in wheat tissues exposed to Hg stress. In addition, the nitrosative stress induced by Hg-stress in terms of high nitric oxide content was minimized by various algal extracts. All these regulations by algal extracts are reflected in high membrane stability as denoted by the reduction of lipid peroxidation, lipoxygenase, and methylglyoxal as a sign of reducing oxidative damage and reactive oxygen species (ROS). Conclusion: Thus, we recommended using the macronutrient-deprived algal extracts of Coccomyxa chodatii SAG 216–2 as potential biostimulants of wheat growth under Hg-stress and may be under other stresses. [ABSTRACT FROM AUTHOR]

Aims: Root tissue water can be lost to the dry topsoil via radial water loss (RWL) resulting in root shrinking and loss of contact with the rhizosphere. The root barrier to radial oxygen loss (ROL) has been shown to restrict RWL, therefore we hypothesized that the inducible barrier can be formed as a response to low soil water potential and play a role, together with other root traits, in restricting RWL. Methods: Rice and wheat were grown in hydroponics with contrasting water potential to diagnose ROL barrier formation and to explore how key root traits (ROL barrier, root diameter, root porosity) affect RWL. Moreover, we developed a numerical model predicting RWL as a function of root diameter, root porosity and presence of a barrier to ROL. Results: Methylene blue staining showed that low water potential induced a ROL barrier formation in roots of rice, and also resulted in an apoplastic barrier, as identified by the apoplastic tracer periodic acid. The barrier significantly restricted RWL, but root diameter and tissue porosity also influenced RWL. Our numerical model was able to reflect the empirical data and clearly demonstrated that thick roots and a barrier to ROL restricts RWL while cortical porosity accelerates RWL. Conclusions: Our modelling approach highlighted that increase in root tissue porosity, a common response to drought, conserves water when new roots are formed, but the higher desiccation risk related to high-porosity roots can be effectively counteracted by forming thick roots or even better, by a barrier to ROL. [ABSTRACT FROM AUTHOR]

Aims: This study investigated the mycorrhizal responsiveness of modern hexaploid wheat and its ancestors under different soil fertility and inferred which ancestor contributed primarily to the mycorrhizal responsiveness of modern wheat. Methods: Three or four accessions of each of five species, including hexaploid bread wheat (Triticum aestivum; AABBDD genome), Triticum urartu (AA), Aegilops speltoides (BB), Aegilops tauschii (DD), and Triticum turgidum (AABB), were used to conduct the greenhouse experiment. An artificially synthesized hexaploid wheat accession and its AABB and DD parents were also analyzed. Plants were inoculated or not with arbuscular mycorrhizal fungi and grown under individual or combined nitrogen (N) and phosphorus (P) additions. Plant and fungal performance and plant's mycorrhizal growth response (MGR) were measured. Results: Mycorrhizal colonization and plant's MGRs were affected strongly by host species or accession, N or P additions, and their interactions. Mycorrhizal colonization was relatively lower in hexaploid wheat and responded negatively to N addition. The MGRs of plants, ranging from positive to negative across accessions or nutrient treatments, were statistically positive for B genome donor A. speltoides but neutral for the other species. The MGR pattern of the synthetic hexaploid wheat was similar to that of its AABB parent but differed considerably from the D genome donor A. tauschii. Conclusions: This study demonstrates complex interactive effects of host identity and soil N and P availability on the mycorrhizal phenotypes of wheat, and speculates that the mycorrhizal responsiveness of modern hexaploid wheat may be controlled by both A and B genomes. [ABSTRACT FROM AUTHOR]

Aim: Chromium (Cr) is a toxic elements and in high concentrations are phytotoxic. This study aimed to test the combined applications of poultry litter biochar and inorganic-fertilizers to ameliorate Cr toxicity. Methods: Biochar, made of poultry litter, was added to Cr contaminated soils (0, 30 and 60 mg kg-1 Cr) either solely or in combination with mineral N fertilizers to ameliorate Cr stress in wheat grown on the contaminated soils for six weeks. A eleven amendments were added to achieve fixed rates of NPK inputs among treatments. Several parameters were used to identify Cr stress coping mechanisms. Results: Root and shoot lengths and their dry weights decreased significantly with increasing Cr contamination level in soil. Under such stressful conditions, the amounts of oxidative stress indicators like Malonaldehyde (MDA) and H2O2 increased considerably. Antioxidants rose significantly in these plants. Biochar and/or NPK treatments lessened significantly the oxidative stress indicators in plant, while improved wheat growth parameters. The treatments of Biochar + NPK had the most profound effects for plant fresh weight and length, antioxidant constituents while recorded the least concentrations of Cr in both roots and shoot. Conclusions: Combined poultry litter biochar and NPK inorganic are potential improving biochemical attributes responsible of coping Cr stress. [ABSTRACT FROM AUTHOR]

Background and aims: Low-grade potassium (K) bearing minerals like waste mica and K-rich crop residues can be explored as an alternative K source. However, waste mica's low available K limits its efficacy. This study aims to use waste mica with a native K solubilizing bacteria (KSB) isolated from Alfisols near mica mines along with rice residue to enhance K availability in a K deficient Alfisol.A novel KSB (JHKSB4), identified as Acinetobacter sp was isolated from soils of mica mining areas in Jharkhand, India. An incubation and pot experiment were conducted using JHKSB4, waste mica and rice residue in a K-deficient Alfisol to assess the release of K fractions and K recovery percentage.Incubation study revealed that waste mica with JHKSB4 and rice residue significantly increased the water-soluble K and exchangeable K contents in soil over mica alone. Pot experiment revealed that combination of mica, JHKSB4 and rice residue could increase 43-61% K uptake by wheat over control but could not exceed the impact of muriate of potash (MOP). Residual impact of this treatment was also observed on K recovery in rice crop. The changes in surface morphology of mica through scanning electron microscopy indicated dissolution of waste mica due to action of JHKSB4 and rice residue.This study established the potential of waste mica treated with JHKSB4 and rice residue as a supplementary K-source for crops. It recorded a K recovery of about 33% of that achieved with MOP. Thus, use of biologically treated waste mica could be a gamechanger in the realm of sustainable K management by partially replacing MOP.Methods: Low-grade potassium (K) bearing minerals like waste mica and K-rich crop residues can be explored as an alternative K source. However, waste mica's low available K limits its efficacy. This study aims to use waste mica with a native K solubilizing bacteria (KSB) isolated from Alfisols near mica mines along with rice residue to enhance K availability in a K deficient Alfisol.A novel KSB (JHKSB4), identified as Acinetobacter sp was isolated from soils of mica mining areas in Jharkhand, India. An incubation and pot experiment were conducted using JHKSB4, waste mica and rice residue in a K-deficient Alfisol to assess the release of K fractions and K recovery percentage.Incubation study revealed that waste mica with JHKSB4 and rice residue significantly increased the water-soluble K and exchangeable K contents in soil over mica alone. Pot experiment revealed that combination of mica, JHKSB4 and rice residue could increase 43-61% K uptake by wheat over control but could not exceed the impact of muriate of potash (MOP). Residual impact of this treatment was also observed on K recovery in rice crop. The changes in surface morphology of mica through scanning electron microscopy indicated dissolution of waste mica due to action of JHKSB4 and rice residue.This study established the potential of waste mica treated with JHKSB4 and rice residue as a supplementary K-source for crops. It recorded a K recovery of about 33% of that achieved with MOP. Thus, use of biologically treated waste mica could be a gamechanger in the realm of sustainable K management by partially replacing MOP.Results: Low-grade potassium (K) bearing minerals like waste mica and K-rich crop residues can be explored as an alternative K source. However, waste mica's low available K limits its efficacy. This study aims to use waste mica with a native K solubilizing bacteria (KSB) isolated from Alfisols near mica mines along with rice residue to enhance K availability in a K deficient Alfisol.A novel KSB (JHKSB4), identified as Acinetobacter sp was isolated from soils of mica mining areas in Jharkhand, India. An incubation and pot experiment were conducted using JHKSB4, waste mica and rice residue in a K-deficient Alfisol to assess the release of K fractions and K recovery percentage.Incubation study revealed that waste mica with JHKSB4 and rice residue significantly increased the water-soluble K and exchangeable K contents in soil over mica alone. Pot experiment revealed that combination of mica, JHKSB4 and rice residue could increase 43-61% K uptake by wheat over control but could not exceed the impact of muriate of potash (MOP). Residual impact of this treatment was also observed on K recovery in rice crop. The changes in surface morphology of mica through scanning electron microscopy indicated dissolution of waste mica due to action of JHKSB4 and rice residue.This study established the potential of waste mica treated with JHKSB4 and rice residue as a supplementary K-source for crops. It recorded a K recovery of about 33% of that achieved with MOP. Thus, use of biologically treated waste mica could be a gamechanger in the realm of sustainable K management by partially replacing MOP.Conclusions: Low-grade potassium (K) bearing minerals like waste mica and K-rich crop residues can be explored as an alternative K source. However, waste mica's low available K limits its efficacy. This study aims to use waste mica with a native K solubilizing bacteria (KSB) isolated from Alfisols near mica mines along with rice residue to enhance K availability in a K deficient Alfisol.A novel KSB (JHKSB4), identified as Acinetobacter sp was isolated from soils of mica mining areas in Jharkhand, India. An incubation and pot experiment were conducted using JHKSB4, waste mica and rice residue in a K-deficient Alfisol to assess the release of K fractions and K recovery percentage.Incubation study revealed that waste mica with JHKSB4 and rice residue significantly increased the water-soluble K and exchangeable K contents in soil over mica alone. Pot experiment revealed that combination of mica, JHKSB4 and rice residue could increase 43-61% K uptake by wheat over control but could not exceed the impact of muriate of potash (MOP). Residual impact of this treatment was also observed on K recovery in rice crop. The changes in surface morphology of mica through scanning electron microscopy indicated dissolution of waste mica due to action of JHKSB4 and rice residue.This study established the potential of waste mica treated with JHKSB4 and rice residue as a supplementary K-source for crops. It recorded a K recovery of about 33% of that achieved with MOP. Thus, use of biologically treated waste mica could be a gamechanger in the realm of sustainable K management by partially replacing MOP. [ABSTRACT FROM AUTHOR]

Aims: Phytate is the most abundant form of organic phosphorus (P) in soil. The plasticity of plants changes in response to various environmental gradients. It is still unknown how phytate-P and the arbuscular mycorrhizal fungi (AMF) symbiosis affect plant traits. The purpose of this study was to understand the interaction between phytate-P availability, AMF symbiosis, and plant traits, which can provide valuable insights into optimizing nutrient uptake and plant growth in agricultural systems.We used six varieties of wheat (Triticum aestivum L.) that were cultivated in pots with or without AMF under five different levels of phytate-P supply (0, 20, 50, 100, and 200 mg phytate-P per kg soil).The incorporation of AMF reduced shoot traits (e.g., shoot biomass and shoot N and P content), root-system plasticity (root-to-shoot ratio), and morphological trait plasticity (specific root length), while phytase activity did not significantly vary. Additionally, the rhizosphere phytase activity of wheat with AMF inoculation substantially increased under P50 and P100 conditions, consistent with mycorrhizal colonization. The mycorrhizal P responsiveness of wheat exhibited a positive correlation with release year but a negative correlation with phytase activity.The mycorrhizal colonization may increase phytase activity. Wheat with AMF showed reduced the plasticity of aboveground traits such as shoot biomass, shoot N and P content, and root-system traits (root-to-shoot ratio), as well as decreased production of organic acids.Methods: Phytate is the most abundant form of organic phosphorus (P) in soil. The plasticity of plants changes in response to various environmental gradients. It is still unknown how phytate-P and the arbuscular mycorrhizal fungi (AMF) symbiosis affect plant traits. The purpose of this study was to understand the interaction between phytate-P availability, AMF symbiosis, and plant traits, which can provide valuable insights into optimizing nutrient uptake and plant growth in agricultural systems.We used six varieties of wheat (Triticum aestivum L.) that were cultivated in pots with or without AMF under five different levels of phytate-P supply (0, 20, 50, 100, and 200 mg phytate-P per kg soil).The incorporation of AMF reduced shoot traits (e.g., shoot biomass and shoot N and P content), root-system plasticity (root-to-shoot ratio), and morphological trait plasticity (specific root length), while phytase activity did not significantly vary. Additionally, the rhizosphere phytase activity of wheat with AMF inoculation substantially increased under P50 and P100 conditions, consistent with mycorrhizal colonization. The mycorrhizal P responsiveness of wheat exhibited a positive correlation with release year but a negative correlation with phytase activity.The mycorrhizal colonization may increase phytase activity. Wheat with AMF showed reduced the plasticity of aboveground traits such as shoot biomass, shoot N and P content, and root-system traits (root-to-shoot ratio), as well as decreased production of organic acids.Results: Phytate is the most abundant form of organic phosphorus (P) in soil. The plasticity of plants changes in response to various environmental gradients. It is still unknown how phytate-P and the arbuscular mycorrhizal fungi (AMF) symbiosis affect plant traits. The purpose of this study was to understand the interaction between phytate-P availability, AMF symbiosis, and plant traits, which can provide valuable insights into optimizing nutrient uptake and plant growth in agricultural systems.We used six varieties of wheat (Triticum aestivum L.) that were cultivated in pots with or without AMF under five different levels of phytate-P supply (0, 20, 50, 100, and 200 mg phytate-P per kg soil).The incorporation of AMF reduced shoot traits (e.g., shoot biomass and shoot N and P content), root-system plasticity (root-to-shoot ratio), and morphological trait plasticity (specific root length), while phytase activity did not significantly vary. Additionally, the rhizosphere phytase activity of wheat with AMF inoculation substantially increased under P50 and P100 conditions, consistent with mycorrhizal colonization. The mycorrhizal P responsiveness of wheat exhibited a positive correlation with release year but a negative correlation with phytase activity.The mycorrhizal colonization may increase phytase activity. Wheat with AMF showed reduced the plasticity of aboveground traits such as shoot biomass, shoot N and P content, and root-system traits (root-to-shoot ratio), as well as decreased production of organic acids.Conclusions: Phytate is the most abundant form of organic phosphorus (P) in soil. The plasticity of plants changes in response to various environmental gradients. It is still unknown how phytate-P and the arbuscular mycorrhizal fungi (AMF) symbiosis affect plant traits. The purpose of this study was to understand the interaction between phytate-P availability, AMF symbiosis, and plant traits, which can provide valuable insights into optimizing nutrient uptake and plant growth in agricultural systems.We used six varieties of wheat (Triticum aestivum L.) that were cultivated in pots with or without AMF under five different levels of phytate-P supply (0, 20, 50, 100, and 200 mg phytate-P per kg soil).The incorporation of AMF reduced shoot traits (e.g., shoot biomass and shoot N and P content), root-system plasticity (root-to-shoot ratio), and morphological trait plasticity (specific root length), while phytase activity did not significantly vary. Additionally, the rhizosphere phytase activity of wheat with AMF inoculation substantially increased under P50 and P100 conditions, consistent with mycorrhizal colonization. The mycorrhizal P responsiveness of wheat exhibited a positive correlation with release year but a negative correlation with phytase activity.The mycorrhizal colonization may increase phytase activity. Wheat with AMF showed reduced the plasticity of aboveground traits such as shoot biomass, shoot N and P content, and root-system traits (root-to-shoot ratio), as well as decreased production of organic acids. [ABSTRACT FROM AUTHOR]

Background and aims: Operation of both tryptophan-dependent and -independent pathways leading to higher indole-3-acetic acid (IAA) production by certain bacteria is known to beneficially influence plant growth and development. This study aimed to detect the operation of different pathways in bacteria for production of IAA and its derivatives, and evaluate the plant growth promoting potential of such promising bacteria in wheat crop.The bacteria of chickpea origin were screened for IAA production through tryptophan-dependent and independent pathways. The prominent IAA producing bacteria were identified by 16S rRNA gene sequencing and evaluated for their growth promoting, soil and plant nutrient enriching potential in wheat crop (cv. Sujata).Out of the 80 bacteria, three isolates KS-14, BEMS-9–1 and BS-2 were found to produce high levels of IAA and its derivatives by differentially operating both the pathways. These isolates were identified as Brevibacillus formosus, Bacillus paramycoides and Bacillus tequilensis, respectively. Evaluation of various combinations of these promising bacteria showed that the consortium of Br. formosus KS-14 and B. paramycoides BEMS-9–1 along with a 50% recommended dose of fertilizer not only significantly improved the morphological and physiological traits of wheat, but also yield and grain micronutrient loading, mediated through enhanced soil biological activities. This is the first report of the occurrence of tryptophan–independent pathway for IAA production in the three bacilli.This study is a novel approach towards utilizing the bacteria producing IAA and its derivatives through tryptophan-dependent and -independent pathways for their promise as biostimulants in wheat.Methods: Operation of both tryptophan-dependent and -independent pathways leading to higher indole-3-acetic acid (IAA) production by certain bacteria is known to beneficially influence plant growth and development. This study aimed to detect the operation of different pathways in bacteria for production of IAA and its derivatives, and evaluate the plant growth promoting potential of such promising bacteria in wheat crop.The bacteria of chickpea origin were screened for IAA production through tryptophan-dependent and independent pathways. The prominent IAA producing bacteria were identified by 16S rRNA gene sequencing and evaluated for their growth promoting, soil and plant nutrient enriching potential in wheat crop (cv. Sujata).Out of the 80 bacteria, three isolates KS-14, BEMS-9–1 and BS-2 were found to produce high levels of IAA and its derivatives by differentially operating both the pathways. These isolates were identified as Brevibacillus formosus, Bacillus paramycoides and Bacillus tequilensis, respectively. Evaluation of various combinations of these promising bacteria showed that the consortium of Br. formosus KS-14 and B. paramycoides BEMS-9–1 along with a 50% recommended dose of fertilizer not only significantly improved the morphological and physiological traits of wheat, but also yield and grain micronutrient loading, mediated through enhanced soil biological activities. This is the first report of the occurrence of tryptophan–independent pathway for IAA production in the three bacilli.This study is a novel approach towards utilizing the bacteria producing IAA and its derivatives through tryptophan-dependent and -independent pathways for their promise as biostimulants in wheat.Results: Operation of both tryptophan-dependent and -independent pathways leading to higher indole-3-acetic acid (IAA) production by certain bacteria is known to beneficially influence plant growth and development. This study aimed to detect the operation of different pathways in bacteria for production of IAA and its derivatives, and evaluate the plant growth promoting potential of such promising bacteria in wheat crop.The bacteria of chickpea origin were screened for IAA production through tryptophan-dependent and independent pathways. The prominent IAA producing bacteria were identified by 16S rRNA gene sequencing and evaluated for their growth promoting, soil and plant nutrient enriching potential in wheat crop (cv. Sujata).Out of the 80 bacteria, three isolates KS-14, BEMS-9–1 and BS-2 were found to produce high levels of IAA and its derivatives by differentially operating both the pathways. These isolates were identified as Brevibacillus formosus, Bacillus paramycoides and Bacillus tequilensis, respectively. Evaluation of various combinations of these promising bacteria showed that the consortium of Br. formosus KS-14 and B. paramycoides BEMS-9–1 along with a 50% recommended dose of fertilizer not only significantly improved the morphological and physiological traits of wheat, but also yield and grain micronutrient loading, mediated through enhanced soil biological activities. This is the first report of the occurrence of tryptophan–independent pathway for IAA production in the three bacilli.This study is a novel approach towards utilizing the bacteria producing IAA and its derivatives through tryptophan-dependent and -independent pathways for their promise as biostimulants in wheat.Conclusion: Operation of both tryptophan-dependent and -independent pathways leading to higher indole-3-acetic acid (IAA) production by certain bacteria is known to beneficially influence plant growth and development. This study aimed to detect the operation of different pathways in bacteria for production of IAA and its derivatives, and evaluate the plant growth promoting potential of such promising bacteria in wheat crop.The bacteria of chickpea origin were screened for IAA production through tryptophan-dependent and independent pathways. The prominent IAA producing bacteria were identified by 16S rRNA gene sequencing and evaluated for their growth promoting, soil and plant nutrient enriching potential in wheat crop (cv. Sujata).Out of the 80 bacteria, three isolates KS-14, BEMS-9–1 and BS-2 were found to produce high levels of IAA and its derivatives by differentially operating both the pathways. These isolates were identified as Brevibacillus formosus, Bacillus paramycoides and Bacillus tequilensis, respectively. Evaluation of various combinations of these promising bacteria showed that the consortium of Br. formosus KS-14 and B. paramycoides BEMS-9–1 along with a 50% recommended dose of fertilizer not only significantly improved the morphological and physiological traits of wheat, but also yield and grain micronutrient loading, mediated through enhanced soil biological activities. This is the first report of the occurrence of tryptophan–independent pathway for IAA production in the three bacilli.This study is a novel approach towards utilizing the bacteria producing IAA and its derivatives through tryptophan-dependent and -independent pathways for their promise as biostimulants in wheat. [ABSTRACT FROM AUTHOR]

Background and aims: Global wheat production is under threat due to climate change, specifically heat and drought and their combination. This study aims to address the root trait responses of heat-tolerant wheat genotypes to drought.The variability in root traits of CIMMYT wheat lines, which were previously developed for heat stress tolerance (HTWL), was evaluated alongside 10 Pakistani-approved varieties under three cultivation conditions and soil moisture levels.Our findings revealed that the plasticity of the wheat root system is highly pronounced, with rhizosphere conditions exerting a more substantial influence (5–49%) than the genotypic response (1–14%). Furthermore, in the hydroponic and pot system, we noted higher maximum-root length (1.5–1.8 fold) and root-to-shoot ratio (3.4–10.6 fold) as compared to field condition, while the root biomass was substantially higher in the field trial (3-57 fold). Nonetheless, persistent drought conditions exerted contrasting impact with reduction in most of the traits except specific root length and harvest index which were increased under drought.The variation in root traits against drought indicates the potential for the development of improved genotypes that can withstand multiple stresses. Furthermore, it is crucial to consider rhizosphere conditions when selecting genotypes, as the plasticity of wheat roots may lead to misinterpretations if rhizosphere conditions are disregarded. Root dry weight and root-to-shoot ratio are more stable traits as compared to maximum root length and specific root length. It is recommended to evaluate a broader range of rhizosphere conditions to select tolerant genotypes.Methods: Global wheat production is under threat due to climate change, specifically heat and drought and their combination. This study aims to address the root trait responses of heat-tolerant wheat genotypes to drought.The variability in root traits of CIMMYT wheat lines, which were previously developed for heat stress tolerance (HTWL), was evaluated alongside 10 Pakistani-approved varieties under three cultivation conditions and soil moisture levels.Our findings revealed that the plasticity of the wheat root system is highly pronounced, with rhizosphere conditions exerting a more substantial influence (5–49%) than the genotypic response (1–14%). Furthermore, in the hydroponic and pot system, we noted higher maximum-root length (1.5–1.8 fold) and root-to-shoot ratio (3.4–10.6 fold) as compared to field condition, while the root biomass was substantially higher in the field trial (3-57 fold). Nonetheless, persistent drought conditions exerted contrasting impact with reduction in most of the traits except specific root length and harvest index which were increased under drought.The variation in root traits against drought indicates the potential for the development of improved genotypes that can withstand multiple stresses. Furthermore, it is crucial to consider rhizosphere conditions when selecting genotypes, as the plasticity of wheat roots may lead to misinterpretations if rhizosphere conditions are disregarded. Root dry weight and root-to-shoot ratio are more stable traits as compared to maximum root length and specific root length. It is recommended to evaluate a broader range of rhizosphere conditions to select tolerant genotypes.Results: Global wheat production is under threat due to climate change, specifically heat and drought and their combination. This study aims to address the root trait responses of heat-tolerant wheat genotypes to drought.The variability in root traits of CIMMYT wheat lines, which were previously developed for heat stress tolerance (HTWL), was evaluated alongside 10 Pakistani-approved varieties under three cultivation conditions and soil moisture levels.Our findings revealed that the plasticity of the wheat root system is highly pronounced, with rhizosphere conditions exerting a more substantial influence (5–49%) than the genotypic response (1–14%). Furthermore, in the hydroponic and pot system, we noted higher maximum-root length (1.5–1.8 fold) and root-to-shoot ratio (3.4–10.6 fold) as compared to field condition, while the root biomass was substantially higher in the field trial (3-57 fold). Nonetheless, persistent drought conditions exerted contrasting impact with reduction in most of the traits except specific root length and harvest index which were increased under drought.The variation in root traits against drought indicates the potential for the development of improved genotypes that can withstand multiple stresses. Furthermore, it is crucial to consider rhizosphere conditions when selecting genotypes, as the plasticity of wheat roots may lead to misinterpretations if rhizosphere conditions are disregarded. Root dry weight and root-to-shoot ratio are more stable traits as compared to maximum root length and specific root length. It is recommended to evaluate a broader range of rhizosphere conditions to select tolerant genotypes.Conclusions: Global wheat production is under threat due to climate change, specifically heat and drought and their combination. This study aims to address the root trait responses of heat-tolerant wheat genotypes to drought.The variability in root traits of CIMMYT wheat lines, which were previously developed for heat stress tolerance (HTWL), was evaluated alongside 10 Pakistani-approved varieties under three cultivation conditions and soil moisture levels.Our findings revealed that the plasticity of the wheat root system is highly pronounced, with rhizosphere conditions exerting a more substantial influence (5–49%) than the genotypic response (1–14%). Furthermore, in the hydroponic and pot system, we noted higher maximum-root length (1.5–1.8 fold) and root-to-shoot ratio (3.4–10.6 fold) as compared to field condition, while the root biomass was substantially higher in the field trial (3-57 fold). Nonetheless, persistent drought conditions exerted contrasting impact with reduction in most of the traits except specific root length and harvest index which were increased under drought.The variation in root traits against drought indicates the potential for the development of improved genotypes that can withstand multiple stresses. Furthermore, it is crucial to consider rhizosphere conditions when selecting genotypes, as the plasticity of wheat roots may lead to misinterpretations if rhizosphere conditions are disregarded. Root dry weight and root-to-shoot ratio are more stable traits as compared to maximum root length and specific root length. It is recommended to evaluate a broader range of rhizosphere conditions to select tolerant genotypes. [ABSTRACT FROM AUTHOR]

Background and aim: Plant-available silicon (Si) is limited in strongly weathered tropical soils. The aim of the study was to evaluate Si fertilisation as a strategy to improve phosphorus (P) fertiliser use efficiency on acidic tropical soil, and the potential of using glacial rock flour (GRF) as a source of Si. Methods: Wheat (Triticum aestivum cv. Benchmark) plants were grown in a pot experiment in an oxisol soil. Si was supplied as either GRF or silicic acid (SiA) at low and sufficient P levels. A soil incubation study and a compartmented pot experiment were also included to assess how soil chemistry was affected by the Si sources both with and without plants. Results: Addition of Si as either GRF or SiA doubled shoot biomass under limited P conditions, and the combined treatment quadrupled it. SiA led to increased P uptake under P-limited conditions, while GRF did not. Soil incubation showed that only SiA increased P availability in bulk soil. The addition of SiA in combination with GRF led to increased root exudation of citric and oxalic acid. Localised weathering of GRF resulted in higher rhizosphere pH, but did not affect rhizosphere P availability or organic acid exudation. Conclusion: Si released from GRF can rejuvenate strongly weathered agricultural soils, improve stress tolerance in plants and ultimately increase yields but GRF does not improve P availability on acidic soils. [ABSTRACT FROM AUTHOR]

Purpose: Silicon (Si) accumulation is an important strategy for plant defense against biotic and abiotic stress. Solid amorphous silica (ASi) deposits have been found to protect plants against different stressors (e.g., drought stress, ultraviolet radiation, herbivory, and pests). Most research on ASi deposits and their subsequent function is conducted under lab conditions. However, it is still unclear at which stage in ontogeny ASi deposits are developed to fulfill their function in plant protection under field conditions. Methods: We combined SEM–EDX, NMR spectroscopy, and Si extractions to analyze silicification patterns in wheat leaves (blades and sheaths) in relation to ontogeny and soil Si availability. Results: Silicification patterns in wheat leaves varied strongly in intensity between four different growth stages (tillering, stem extension, heading, and grain filling) and ASi deposition did not just continuously increase over the growing season. Newly formed leaf tissues showed relatively low Si concentrations, which increased over time. A high condensation state of the silica bodies and trichomes was found at all growth stages, referring to a high rigidity of the silica bodies. Conclusions: Our results indicate that development of ASi deposits in wheat leaves depends on growth stage and Si availability. Detailed knowledge on solid ASi deposition in wheat during ontogeny and its consequences for stress mitigation is crucial for farmers worldwide. [ABSTRACT FROM AUTHOR]

Aims: This study was designed to assess the effect of nanosilicab fertilizer on Triticum aestivum under drought stress. Methods: The plants were grown in pots having the soil incubated with SiO2 NPs, biofertilizer and nanosilicab. The experimental design was completely randomized design and drought stress was applied at stem elongation stage. Plants were maintained in the pots till the collection of yield. Results: Nanosilicab enhanced the germination percentage, germination index, and germination vigor index by 23.07%, 14.49%, and 93.10% under control and 14.42%, 10.52%, and 46.15% under drought stress. In the pot experiment, the soil was treated with 150 mg/kg silicon dioxide nanoparticles (SiO2), 1% biofertilizer and, 1% nanosilicab before sowing. Nanosilicab increased shoot length and root length by 34.77%, and 16.88% under control and 30.58%, and 21.56% under stress conditions, respectively. It also increased photosynthetic pigments, osmolytes content, relative water content, membrane stability index, phenol, and flavonoid content. The increase in antioxidant activity was significant by the application of nanosilicab i.e. the augmentation in catalase, peroxidase, and superoxide dismutase was 68.65%, 83.69%, and 85.99%, respectively. It also increased indole acetic acid and cytokinin by 22.28% and 14.79% in comparison to control. The improvement in hundred-grain weight and grains per spike by the use of nanosilicab was 36.25%, and 38.76% under control, and 27.47%, and 22.59% under stress conditions. Conclusion: The positive effect of nanosilicab on the roots of the plants improved the growth of plants significantly and this fertilizer showed potential for application on crops. [ABSTRACT FROM AUTHOR]

Background and aims: It is known that the single and combined use of phosphate-solubilizing bacteria (PSB) and silicon (Si) have the potential to improve the uptake of phosphorus (P) by plants in calcareous soils. However, it was unclear which form of Si in soil would have the most profound effects on the uptake of P by wheat plant inoculated with PSB. Here we investigated the effect of Si fertilizer on chemical forms of Si and P uptake by wheat plant inoculated with PSB in a calcareous soil. Determining different forms of Si in calcareous soils with a low P supply is essential to better understand the capacity of these forms to supply wheat plant with P in the presence of PSB. Methods: A pot trial in a completely randomized design with factorial arrangement in 3 repetitions under greenhouse conditions was adopted to investigate the effect of Si fertilizer alone or in combination with PSB on the uptake of P and Si by wheat plant grown on a calcareous soil with low available P. Experimental treatments included: Si factor at four levels of 0, 150, 300, and 600 mg Si kg−1 from silicic acid source and PSB strains factor at three levels of B0 (control), Pseudomonas sp. FA1, and Bacillus simplex UT1. The impacts of Si levels and PSB on shoot and root dry weight and the wheat shoot uptake of Si and P were measured. Also, the chemical forms of Si in wheat rhizosphere and non-rhizosphere soil and the regression models of the variables were studied to better understand the mechanisms of this process. Results: With increasing the levels of Si, the plant available Si with the lowest level, adsorbed Si, and amorphous Si with the highest level in both the rhizosphere and non-rhizosphere soil increased. In addition, Si fertilization-mediated increase at level of the soil Si fractions was intensified in the presence of PSB strains. The highest plant available Si (75.50 mg Si kg−1 soil) was obtained from the treatment of 600 mg Si kg−1 soil in the presence of Pseudomonas sp. FA1. The combined application of Si and PSB strains also increased the wheat shoot dry weight by 3.5 times compared to the control treatments. The use of Si alone at level of 300 mg Si kg−1 also increased the wheat shoot content of P by 2.3 times compared to the control treatment. However, the combined application of Pseudomonas sp. FA1 and Si at level of 600 mg Si kg−1 increased the wheat shoot content of P by 4 times compared to the control treatment. According to the correlations among the studied parameters, in addition to the expected positive correlation between plant available Si of wheat rhizosphere soil and the measured parameters, a positive and significant correlation between adsorbed Si of wheat rhizosphere soil and the shoot uptake of Si (r2 = 0.84, P < 0.01) and the shoot uptake of P (r2 = 0.58, P < 0.05) was also observed in this study. Conclusions: The information on the distribution of different forms of Si and the availability of P following the combined use of PSB strains and Si in this study (e.g., the role of rhizosphere adsorbed Si in increasing the wheat shoot uptake of P) may help in better management of P-fertilization in calcareous soils. [ABSTRACT FROM AUTHOR]

Background and aims: This study was the first to test the efficiency of monitoring root electrical capacitance (CR*) non-destructively in the field to evaluate crop development under different environmental conditions. Methods: A free-air CO2 enrichment (FACE) experiment was performed with two winter wheat cultivars, two levels (low and high) of nitrogen supply and two (ambient and elevated) of [CO2] in three replicate plots over two years. The validity of CR* as a proxy for root uptake activity was confirmed by tracking the ceptometer-based leaf area index (LAI). Results: Repeated CR* measurements clearly demonstrated the seasonal dynamics in root development, with a peak at flowering, and the delayed growth in the second year caused by the unfavourable meteorological conditions. From the vegetative to flowering stages, CR* was strongly correlated with LAI (R2: 0.897–0.962). The positive effect of higher N supply and elevated [CO2] on crop growth was clearly indicated by the higher CR* values, associated with increased LAI, shoot dry mass (SDM) at flowering and grain yield (GY). The maximum CR* was closely related to GY (R2: 0.805 and 0.867) when the data were pooled across the N and CO2 treatments and the years. Unlike CR* and GY, SDM and LAI were significantly lower in the second year, presumably due to the enhanced root/shoot ratio induced by a severe spring drought. Conclusions: The present results convincingly demonstrated the potential of the in situ root capacitance method to assess root responses dynamically, and to predict crop GY. [ABSTRACT FROM AUTHOR]

Background and aims: Measurement of Nutrient use efficiency (NUE) can be useful for evaluating crops under stressful conditions. The study aimed to elucidate the NUE regulation post-NP (Nitrogen and Phosphorus) supplementation under the combined effect of drought (D) and arsenic (As) stress in wheat seedlings.Pheno-physiological traits, N-P assimilating enzymes, and nutrient accumulation patterns, along with N-P usage efficiency, were explored to determine the effect of NP under D + As at short (7 days) and long exposures (15 days).The results showed that dual stress hindered plant growth by interfering with essential metabolic mechanisms and reducing NP acquisition via altered root morphology. Additionally, hampered NP-assimilation was depicted via impaired NO3− content and NP-assimilating enzymes correlating with increased oxidative damages and reduced NP-accumulation. Concurrently, increased NH4+ content caused toxicity to the plant. NP enrichment improved nutrient content (except for Zn and Cu at 15 days) and growth-related functions via increased NP capture, and assimilatory activity at both exposures. The Glutamate-dehydrogenase (GDH) enzyme appeared as a toxicity cleanser, uplifting assimilation. This further augmented NUE, confirmed by an increment in Physiological Nutrient Use Efficiency (PNUE), Agronomical Nutrient Use Efficiency (ANUE), and Nutrient Recovery Efficiency (NRE). Plants facing drought performed better than those treated with As at 15 days, highlighting the tolerant nature of HD-3237 wheat variety against drought stress, and sensitive nature towards As.The present findings revealed that N and P have a role in boosting NUE-related mechanisms that enable plants to withstand combined impacts of drought and As stress.Methods: Measurement of Nutrient use efficiency (NUE) can be useful for evaluating crops under stressful conditions. The study aimed to elucidate the NUE regulation post-NP (Nitrogen and Phosphorus) supplementation under the combined effect of drought (D) and arsenic (As) stress in wheat seedlings.Pheno-physiological traits, N-P assimilating enzymes, and nutrient accumulation patterns, along with N-P usage efficiency, were explored to determine the effect of NP under D + As at short (7 days) and long exposures (15 days).The results showed that dual stress hindered plant growth by interfering with essential metabolic mechanisms and reducing NP acquisition via altered root morphology. Additionally, hampered NP-assimilation was depicted via impaired NO3− content and NP-assimilating enzymes correlating with increased oxidative damages and reduced NP-accumulation. Concurrently, increased NH4+ content caused toxicity to the plant. NP enrichment improved nutrient content (except for Zn and Cu at 15 days) and growth-related functions via increased NP capture, and assimilatory activity at both exposures. The Glutamate-dehydrogenase (GDH) enzyme appeared as a toxicity cleanser, uplifting assimilation. This further augmented NUE, confirmed by an increment in Physiological Nutrient Use Efficiency (PNUE), Agronomical Nutrient Use Efficiency (ANUE), and Nutrient Recovery Efficiency (NRE). Plants facing drought performed better than those treated with As at 15 days, highlighting the tolerant nature of HD-3237 wheat variety against drought stress, and sensitive nature towards As.The present findings revealed that N and P have a role in boosting NUE-related mechanisms that enable plants to withstand combined impacts of drought and As stress.Results: Measurement of Nutrient use efficiency (NUE) can be useful for evaluating crops under stressful conditions. The study aimed to elucidate the NUE regulation post-NP (Nitrogen and Phosphorus) supplementation under the combined effect of drought (D) and arsenic (As) stress in wheat seedlings.Pheno-physiological traits, N-P assimilating enzymes, and nutrient accumulation patterns, along with N-P usage efficiency, were explored to determine the effect of NP under D + As at short (7 days) and long exposures (15 days).The results showed that dual stress hindered plant growth by interfering with essential metabolic mechanisms and reducing NP acquisition via altered root morphology. Additionally, hampered NP-assimilation was depicted via impaired NO3− content and NP-assimilating enzymes correlating with increased oxidative damages and reduced NP-accumulation. Concurrently, increased NH4+ content caused toxicity to the plant. NP enrichment improved nutrient content (except for Zn and Cu at 15 days) and growth-related functions via increased NP capture, and assimilatory activity at both exposures. The Glutamate-dehydrogenase (GDH) enzyme appeared as a toxicity cleanser, uplifting assimilation. This further augmented NUE, confirmed by an increment in Physiological Nutrient Use Efficiency (PNUE), Agronomical Nutrient Use Efficiency (ANUE), and Nutrient Recovery Efficiency (NRE). Plants facing drought performed better than those treated with As at 15 days, highlighting the tolerant nature of HD-3237 wheat variety against drought stress, and sensitive nature towards As.The present findings revealed that N and P have a role in boosting NUE-related mechanisms that enable plants to withstand combined impacts of drought and As stress.Conclusion: Measurement of Nutrient use efficiency (NUE) can be useful for evaluating crops under stressful conditions. The study aimed to elucidate the NUE regulation post-NP (Nitrogen and Phosphorus) supplementation under the combined effect of drought (D) and arsenic (As) stress in wheat seedlings.Pheno-physiological traits, N-P assimilating enzymes, and nutrient accumulation patterns, along with N-P usage efficiency, were explored to determine the effect of NP under D + As at short (7 days) and long exposures (15 days).The results showed that dual stress hindered plant growth by interfering with essential metabolic mechanisms and reducing NP acquisition via altered root morphology. Additionally, hampered NP-assimilation was depicted via impaired NO3− content and NP-assimilating enzymes correlating with increased oxidative damages and reduced NP-accumulation. Concurrently, increased NH4+ content caused toxicity to the plant. NP enrichment improved nutrient content (except for Zn and Cu at 15 days) and growth-related functions via increased NP capture, and assimilatory activity at both exposures. The Glutamate-dehydrogenase (GDH) enzyme appeared as a toxicity cleanser, uplifting assimilation. This further augmented NUE, confirmed by an increment in Physiological Nutrient Use Efficiency (PNUE), Agronomical Nutrient Use Efficiency (ANUE), and Nutrient Recovery Efficiency (NRE). Plants facing drought performed better than those treated with As at 15 days, highlighting the tolerant nature of HD-3237 wheat variety against drought stress, and sensitive nature towards As.The present findings revealed that N and P have a role in boosting NUE-related mechanisms that enable plants to withstand combined impacts of drought and As stress. [ABSTRACT FROM AUTHOR]

Purpose: Iron (Fe) deficiency seriously affects crop growth and yield. This study investigated whether and how an endophytic isolate, strain Bacillus sp. WR12, alleviates Fe deficiency in wheat (Triticum aestivum L.). Methods: Bacillus sp. WR12 and wheat seedlings were hydroponically co-cultured for 2 weeks under Fe-deficient conditions. To evaluate the Fe deficiency alleviating potential, wheat growth parameters were compared. To elucidate possible mechanisms, the genome of WR12 was sequenced, and production of siderophores was detected. In addition, transcriptomes of wheat root were compared, and accumulation of phenolic compounds was measured. Results: Bacillus sp. WR12 significantly increased root length and dry weight, leaf chlorophyll content and Fe content in Fe-deficient wheat seedlings. Genome analysis of WR12 and CAS agar diffusion test demonstrated that WR12 had a dhbACEBF operon and produced siderophores. Significant upregulation of this operon and more siderophore synthesis in WR12 were observed when Fe was insufficient. Transcriptomic data of roots indicated change of expression of a large number of genes in Fe-deficient wheat after WR12 inoculation. Particularly, PAL, CYP73A, COMT, F5H, HCT and CAD genes involved in phenylpropane biosynthesis were significantly up-regulated. Moreover, elevated phenol accumulation was detected in the root of wheat after inoculation with WR12 under Fe deficiency. Conclusions: Bacillus sp. WR12 alleviates Fe deficiency in wheat and this can be partially attributed to enhanced siderophore production and phenol accumulation. [ABSTRACT FROM AUTHOR]

Aims: Although elevated atmospheric CO2 and global warming are important climate factors that affect soil carbon sequestration and greenhouse gases emission from agricultural soils, it remains unclear how these factors affect the soil microbial communities that involved in nitrous oxide (N2O) emission. The objectives of this study were to evaluate the interactive effects of elevated CO2 and warming on soil microbial community and its relationship with soil N2O emission. Methods: Soil N2O emission was monitored in a Free-Air CO2 Enrichment facility equipped with warming during wheat growth season. The abundance and community composition of ammonia-oxidizing bacteria (AOB) and archaea (AOA) and denitrifiers (nirK, nirS and nosZ) in the rhizosphere were determined using real-time PCR and Illumina MiSeq sequencing technique. Results: Elevated CO2 increased N2O emission, the abundance of AOB and nirK, the concentration of rhizospheric soil organic carbon (SOC) and total nitrogen (TN); while it decreased the concentration of soil available phosphorus and potassium. Warming decreased soil pH, and the abundance of AOB, nirK and nosZ; and the effect of warming on soil N2O emission, SOC, TN and AOB abundance was significantly interacted with elevated CO2. Under elevated CO2, warming decreased soil N2O emission but increased the concentration of rhizosphere SOC and TN. Pyrosequencing showed that AOB, nirK, and nosZ community compositions were altered by elevated CO2 levels, and redundancy analyses further showed that variations in SOC, TN and pH determined these community compositions. Soil N2O emission was positively corelated with soil pH, the content of SOC and nitrate, and the abundance of AOB and nirK. Conclusions: Our results demonstrated that future climate change of elevated CO2 plus warming will not lead to a significant increase in agricultural soil N2O emission. Ammonia oxidizer (AOB) and denitrifier (nirK) are the key soil microbial community that regulate the response of soil N2O emission to elevated CO2 and warming. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the effect of Serendipita indica, an endophytic fungus, inoculation of different wheat (Triticum aestivum) cultivars on the rhizosphere physical quality. Methods: S. indica inoculated and uninoculated seedlings of wheat cultivars (Roshan, Ghods, Kavir and Pishtaz) were grown in rhizoboxes. Plants were harvested and intact samples were taken from the rhizosphere to measure soil organic carbon (SOC), hot-water soluble carbohydrates (HWSC), carbon mineralization rate (CMR), water repellency index (RI) by the sorptivity method, and aggregate stability by the high energy moisture characteristic (HEMC) method. Root mucilages of inoculated and uninoculated seedlings were also collected for measuring total polysaccharides (TPmucilage). Results: The SOC, HWSC, and RI were increased by 146, 83, and 40% and CMR was decreased by 56% in planted treatments, which consequently increased the HEMC aggregate stability indices. S. indica increased SOC, HWSC, RI, and structural stability, and improved the physical quality especially in soil with Roshan and Ghods, which had more extensive root distributions and higher TPmucilage. The changes of soil-physical and hydraulic properties among different wheat cultivars imply that both quantitative and qualitative properties of root exudates have significant effects on soil quality. Soil with Roshan had the highest SOC, HWSC, and root distribution and the lowest aggregate stability. However, soil with Ghods had almost the same SOC and HWSC, but it had the highest stability indices. Conclusion: S. indica inoculation of different wheat cultivars, by increasing SOC and inducing water repellency in the rhizosphere, can improve the aggregate stability and soil physical quality. [ABSTRACT FROM AUTHOR]

Purpose: Agronomic practices are one of the reasons for the increasing accumulation of elements in the soil, including manganese (Mn). Our previous studies have shown that selenium (Se) ions can reduce the toxic actions of metal stress. Those, we studied the effects of Mn—treated as a stressor and Se – as a potential defense in plants. Methods: Mn ions (10 mM) or/and Se (15 μM) were added into hydroponic nutrients of two wheat cultivares. The evaluation of the stress-generating and protective actions were analyzed by biochemical methods and microscopic observations in leaves and roots. Moreover the level of DNA methylation for these tissues was determined. Results: Mn application caused an increase of lipid peroxidation and hydrogen peroxide content in both leaves and roots and was accompanied with a greater absorption of this element by the roots. For other elements (K, Fe, S, P), with the exception of Ca, the reduced their uptake was registered, especially in roots. For roots, Mn stimulated greater, microscopically observed, desorganization in cell structure as compared to leaves, which was accompanied by a quantitative increase in 5-methylcytosine (5-metC) in root meristem. Se application diminished the effects of Mn-stress. Conclusions: These studies is the first in which indicated that global 5-metC level in roots enhancing from dividing meristematic cells to elongating cells of the axial cylinder and cortex. It was suggested that the rise in Ca level can lead to modification of root cells differentiations what may be one of the steps in defense mechanisms. [ABSTRACT FROM AUTHOR]

Aims: Phosphorus (P) fertilizers are often considered an important source of cadmium (Cd) in crop plants. However, increased plant Cd concentrations are not strictly related to the Cd content of P fertilizers. Considering this, we hypothesized that, alternatively, reduction of arbuscular mycorrhizal colonization by P fertilization enhances Cd accumulation in plants. Methods: Wheat and canola as mycorrhizal and non-mycorrhizal species, respectively, were grown under greenhouse conditions with and without soil sterilization. Phosphorus fertilizers with 0.09, 5, and 28 mg Cd kg−1 were applied at different rates with varied zinc (Zn) fertilization. Results: In wheat, all three P fertilizers markedly increased shoot and grain Cd concentrations as P supply was increased, irrespective of the Cd concentration in the fertilizers. These increases were pronounced with soil sterilization or at low zinc supply. Adding mycorrhizal fungi to sterilized soil substantially decreased shoot Cd concentrations. We found a strong negative relationship in wheat between mycorrhizal colonization and shoot Cd concentration, for both high- and low-Cd fertilizers. In contrast to wheat, shoot Cd concentrations in canola showed virtually no response to P supply or soil sterilization. High Zn application also reduced plant Cd concentrations, especially at high P rates. Conclusion: Our findings demonstrate the critical importance of mycorrhizal colonization in reducing Cd accumulation in wheat, and suggest that factors suppressing root mycorrhizal activity including P fertilization, will increase Cd uptake in mycorrhizal plants. [ABSTRACT FROM AUTHOR]

Purpose: Green manuring can increase the plant available fraction of zinc (Zn) in soil, making it a potential approach to increase wheat Zn concentrations and fight human Zn deficiency. We tested whether green manure increases the ability of both the native soil bacteria and inoculated Zn solubilizing bacteria (ZSB) to mobilize Zn. Methods: Wheat was grown in a pot experiment with the following three factors (with or without); (i) clover addition; (ii) soil x-ray irradiation (i.e. elimination of the whole soil biota followed by re-inoculation with the native soil bacteria); and (iii) ZSB inoculation. The incorporation of clover in both the irradiated and the ZSB treatments allowed us to test green manure effects on the mobilization of Zn by indigenous soil bacteria as well as by inoculated strains. Results: Inoculation with ZSB did neither increase soil Zn availability nor wheat Zn uptake. The highest soil Zn availabilities were found when clover was incorporated, particularly in the irradiated soils (containing only soil bacteria). This was partly associated with the stimulation of bacterial activity during the decomposition of the incorporated green manure. Conclusion: The results support that the activity of soil bacteria is intimately involved in the mobilization of Zn following the incorporation of green manure. [ABSTRACT FROM AUTHOR]

Background and objectives: Integrated weed management in commercial wheat production is urgently needed due to increasing herbicide resistance and production costs. Benzoxazinoids (BXs), which include benzoxazinones and benzoxazolinones, are unique bioactive metabolites produced by certain members of the Poaceae including maize, wheat, rye and some dicots. BXs play important roles in plant defence and are causal agents of allelopathic interference. We investigated the role of genetics, environment and crop growth stage on BX abundance in the roots and rhizoplane of selected commercial wheat cultivars, and quantified their microbial transformation products (aminophenoxazinones) in roots and rhizosphere soils. Methods: Cultivar trials of competitive wheat (Triticum aestivum L.) genotypes were conducted in two moderate to low rainfall (449–572 mm) locations in southeastern Australia in 2015 and 2016. Replicated shoot, root, rhizoplane, and rhizosphere soil samples were collected for metabolic profiling at selected crop phenological stages, extracted and further analysed for known benzoxazinoid metabolites by liquid chromatography coupled with high resolution mass spectrometry. Results: Fifteen BXs and related microbially derived aminophenoxazinones were detected in wheat shoots, roots, rhizoplanes and rhizosphere soils in both years and locations. MBOA, HMBOA and HMBOA-Glc were the three most abundant BX metabolites in wheat tissues, with the heritage cultivar Federation producing the highest levels of MBOA. The phytotoxic aminophenoxazinones APO and AMPO were the most abundant BX microbial transformation products and were detected in wheat roots, rhizoplanes and rhizospheres. Abundance varied with cultivar, growth stage, location and year. Conclusions: Microbially-produced aminophenoxazinones generated from both heritage and modern wheat root exudates were detected and quantified in rhizosphere soils, with abundance dependent on cultivar, growth stage, and season. Concentrations of microbial metabolites APO, AMPO, and AAPO were higher in the rhizosphere of young wheat seedlings in contrast to that of mature plants suggesting that phenoxazinone production was upregulated early in the season. Our findings demonstrate that BX metabolites at all life stages of wheat potentially undergo rapid biotransformation to aminophenoxazinones under field conditions, resulting in ecologically relevant concentrations sufficient for weed suppression by certain wheat cultivars. [ABSTRACT FROM AUTHOR]

Aims: Nitrate transporters (NRT) in plants are mainly encoded by the NPF and NRT2 gene families. We aimed to reveal the chromosome distribution, collinearity, coexpression and evolution of the NPF and NRT2 genes in the genome of wheat (Triticum aestivum). Nitrate transport activity of representative proteins was also verified. Methods: Genomic information, collinearity analysis, coexpression network analysis, nitrate transport activity and polymorphism analysis were integrated to identify and characterize the NPF and NRT2 genes. Results: We identified 331 NPF and 46 NRT2 genes in the wheat genome. Tandem duplication was the main driver of the expansion of the NRT2 genes. The NPF genes were mainly distributed on the 2-, 3- and 7- chromosome groups and in the R2b region. The NRT2 genes were mainly distributed on the 6-chromosome group and in the R1 region. Multiple transcription factor families were coexpressed with NPF and NRT2 genes in wheat. Two NPFs and one NRT2 could transport NO3− under either 0.5 mM or 10 mM nitrate concentrations. One hundred and eighty-five NPF and 27 NRT2 genes fit the neutral selection model. Natural variations in NPF genes resulted in differences in the nitrogen uptake of wheat. Conclusions: Duplication events are ubiquitous in NPF and NRT2 gene families in the wheat genome. GRAS may be a previously unrecognized transcription factor that regulates NPF genes expression. It is unreliable to predict the activity of NPF and NRT2 proteins based only on their phylogenetic relationships. Polymorphisms in NPF and NRT2 genes mainly accumulate by random drift. [ABSTRACT FROM AUTHOR]

Aims: Aluminium toxicity in acidic soils adversely affects wheat growth. Foliar-applied magnesium (Mg) contributes to mitigating soil acidity stress in wheat, but the mechanisms are unknown. This study explored the mechanism of foliar-Mg mediated enhancement of wheat growth in acidic soil. Methods: Two contrasting near-isogenic wheat (Triticum aestivum L.) genotypes differing in Al resistance (Al-sensitive ES8 and Al-resistant ET8) were grown to the vegetative stage (Zadoks 24) in a reconstituted acidic soil (pH0.1 M CaCl2 4.0) profile with three rates of foliar Mg (0, 200 and 500 mg Mg L− 1 using MgSO4.7H2O). Magnesium was applied to the foliage twice [14 and 28 days after sowing (DAS)], and plant growth and root exuded carboxylates were measured up to 42 DAS. Results: Applying 200 mg Mg L− 1 to the foliage increased organic acid anion exudation from wheat roots by ~ 2-fold compared to 0 foliar Mg treated plants. The Al-resistant wheat genotype exuded 1.3-fold more malate and citrate from roots than the Al-sensitive genotype in the absence of foliar Mg. Malate exudation was delayed relative to citrate following foliar Mg application. The foliar-applied Mg increased shoot and root dry weight (by ~ 38 %), total root length (by ~ 33 %) and intrinsic water-use efficiency (by ~ 80 %) compared to plants treated with no Mg. Applying foliar Mg decreased soil acidity stress (as shown by a significant increase in chlorophyll fluorescence Fv/Fm ratio) in wheat compared to 0 foliar Mg. Conclusions: Increased malate and citrate exudation is the underlying mechanism of enhanced wheat growth following foliar Mg application under acidic soil conditions. [ABSTRACT FROM AUTHOR]

Background: Environmental approaches for minimizing wheat grain Cd are urgently in need in many parts of the world. While metal-removing strategies like phytoextraction or soil-washing are not suitable to the scenario of farmland Cd pollution, rhizoremediation which aims to reduce crops' Cd uptake by using microbial technology has shown great potentials. Methods and results: In this study, a filamentous fungus strain YZ1 was isolated from wheat farmland soil, which is affiliated to Purpureocillium sp. based on morphological and phylogenetical evidence. The strain YZ1 had a minimum inhibitory concentration of 1 mM Cd and was able to survive at 100 mM Cd, with maximum biomass at 0.4 mM Cd. Comparative transcriptomics showed that little changes in cellular transcriptional patterns occurred at 0.4 mM Cd relative to the control, and substantial transcriptional changes could be detected mainly in substance metabolism/transport genes at 2 mM Cd. Pot culture experiments showed that YZ1 rhizo-inoculation ameliorated Cd stress to wheat substantially, leading to a significant reduction by 23.3% to 26.0% in Cd concentration of wheat seedlings. Further, molecular evidence indicated that YZ1 may colonize the wheat root and impact wheat Cd response by modulating wheat's Cd-associated genes, mainly TaEXPA2, TaVP1, TaMRP3, TaPCS1 and TaTM20, while no effect of YZ1 on culture medium pH or Cd bioavailability was observed. Conclusions: A fungal strain YZ1 showing Cd-loving nature was isolated. The strain YZ1 can be a promising candidate for rhizoremediation of Cd-contaminated farmland in wheat-production areas. [ABSTRACT FROM AUTHOR]

Purpose: Precrops exhibit vigorous deep root growth, especially when grown perennially. However, their contribution to accumulate essential nutrients derived from deeper soil layers in the topsoil has not been quantified. We determined the vertical distribution of phosphorous (P) and potassium (K) affected by contrasting root systems of 3 precrops and their effects on subsequently grown spring wheat. Methods: Three precrops (lucerne, chicory and tall fescue) were grown for 1, 2 and 3 years prior to spring wheat cultivation. We measured plant available soil P and K from 0 to 30 cm to 75–105 cm of soil depth after precropping. Root growth and crop performance of spring wheat as affected by precropping were measured in two repeated trials. Results: We observed maximum 22-fold higher root-length density (RLD; cm cm− 3) of taprooted chicory compared with fibrous-rooted tall fescue in the subsoil. There were significant increases in plant available K in the topsoil by 27 mg kg− 1 over the precrop duration between 1 and 3 years. Grain yield of subsequently grown spring wheat was significantly increased by 10 % and 14 % from 1 year to 3 year-treatments of lucerne and chicory, respectively. Similarly, significant increases in P uptake (7 % and 19 %) and K uptake (21 and 14 %) of spring wheat was noted for the same treatments. Conclusions: Our data suggest that there is potential for the yield of short-season cereals to be improved by increased soil nutrient bioavailability in the topsoil derived from deeper soil layers by the deep roots of perennial precrops. [ABSTRACT FROM AUTHOR]

Background and Aim: Success in agronomic biofortification of maize and wheat is highly variable. This study aimed to elucidate the differences in uptake and translocation of foliar-applied zinc (Zn) in maize (Zea mays L.) and wheat (Triticum aestivum L.) using different experimental approaches. Methods: Old leaves of plants cultured with low or adequate Zn supply in soil were treated with natural Zn (as ZnSO4) or enriched stable isotope 70Zn as SO4 salt. Treated leaves, and the remaining untreated shoot and roots were analyzed for Zn using quantitative (ICP-OES and ICP-MS after acid digestion) and qualitative (fluorescence microscopy after Zinpyr-1 staining) techniques. Results: Application of Zn to a single old leaf resulted in significantly higher increments in Zn concentration of the treated leaf, remaining untreated shoot and roots in wheat than in maize, particularly under low Zn supply. The relative Zn uptake (i.e., the portion of 70Zn taken up by the treated leaf) was also estimated to be significantly higher in wheat than maize, irrespective of the rate of Zn supply to plants. Higher uptake and translocation of Zn in wheat compared to maize was also visualized and demonstrated by using Zinpyr-1 fluorescent dye. Conclusions: Our results conclude that wheat is superior to maize in terms of leaf penetration and uptake, as well as subsequent translocation of foliar-applied Zn, therefore, the agronomic biofortification potential is better for wheat than for maize. [ABSTRACT FROM AUTHOR]