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Exploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO3 to 3‐week‐old tomato cv. Micro‐Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si‐treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress. [ABSTRACT FROM AUTHOR]

The climatic events predicted to increase in intensity and frequency in the near future, including drought, may influence the quality and productivity of several important crops for human nutrition, such as legumes. Herein, two chickpea genotypes (Cicer arietinum) were analysed for their resilience to low water supply: a commercial white chickpea (kabuli) and a traditional black chickpea (desi) with marginal production in occidental countries. Plants were grown under four levels of water supplies (90%, 75%, 50% and 25% of field capacity) and biometric variables (root, shoot, pods and seeds), proxies of plant fitness (water content and oxidative stress) and the seed nutritional profile (protein and mineral concentrations) were analysed at plant maturity. The results show that the water content in shoots and roots decreased with the decrease in water supplies, with kabuli plants generally having higher water content in shoots and desi in roots. The shoot length was significantly higher in kabuli compared to desi, while the root length increased up to 11% in both species with the decrease in water supplies. The root‐to‐shoot ratio was higher in kabuli and increased with the decrease in the water supply, being negatively correlated with the number of pods and seeds per plant. Lipid peroxidation also increased with the decrease in the water supply, having slight positive correlations with plant growth parameters while being negatively correlated with plant productivity. No significant effects of plant genotype and water supply were observed on seed K, Ca and protein, but desi was able to sustain higher P, Mg, Zn, Fe, Mn and B concentrations than kabuli, including at lower water supplies. The results suggest that water stress negatively impacts plant growth and productivity and that the two chickpea genotypes have distinct biomass and water allocation strategies to cope with low water supply. These findings may be useful in strategies for improving the productivity and nutritional profile of chickpea crops under water‐limited conditions. [ABSTRACT FROM AUTHOR]

Drought is increasingly frequent in the context of climate change and is considered a major constraint for crop yield. Water scarcity can impair growth, disturb plant water relations and reduce water use efficiency. Pea (Pisum sativum) is a temperate grain legume rich in protein, fibre, micronutrients and bioactive compounds that can benefit human health. In reducing pea yield because of drought, the intensity and duration of stress are critical. This review describes several drought resistance mechanisms in pea based on morphology, physiology and biochemical changes during/after the water deficit period. Drought tolerance of pea can be managed by adopting strategies such as screening, breeding and marker‐assisted selection. Therefore, various biotechnological approaches have led to the development of drought‐tolerant pea cultivars. Finally, the main objective of the current research is to point out some useful traits for drought tolerance in peas and also, mention the methods that can be useful for future studies and breeding programmes. [ABSTRACT FROM AUTHOR]

The reasons underlying the differential tolerance of Actinidia spp. to the pandemic pathogen Pseudomonas syringae pv. actinidiae (Psa) have not yet been elucidated. We hypothesized that differential plant‐defence strategies linked to transcriptome regulation, phytohormones and primary metabolism might be key and that Actinidia chinensis susceptibility results from an inefficient activation of defensive mechanisms and metabolic impairments shortly following infection. Here, 48 h postinoculation bacterial density was 10‐fold higher in A. chinensis var. deliciosa than in Actinidia arguta, accompanied by significant increases in glutamine, ornithine, jasmonic acid (JA) and salicylic acid (SA) (up to 3.2‐fold). Actinidia arguta showed decreased abscisic acid (ABA) (0.7‐fold), no changes in primary metabolites, and 20 defence‐related genes that were only differentially expressed in this species. These include GLOX1, FOX1, SN2 and RBOHA, which may contribute to its higher tolerance. Results suggest that A. chinensis' higher susceptibility to Psa is due to an inefficient activation of plant defences, with the involvement of ABA, JA and SA, leading to impairments in primary metabolism, particularly the ammonia assimilation cycle. A schematic overview on the interaction between Psa and genotypes with distinct tolerance is provided, highlighting the key transcriptomic and metabolomic aspects contributing to the different plant phenotypes after infection. Summary Statement: The pandemic bacterium P. syringae pv. actinidiae is currently the most important pathogen affecting kiwifruit productivity worldwide. Given the absence of sustainable and effective mitigation strategies, it is imperative to understand plant tolerance mechanisms that could support crop improvement and better agronomical practices. Here, we found that plant susceptibility to Psa results from an inefficient activation of plant defences, involving the jasmonic acid and salicylic acid pathways, and leads to impairments in primary metabolism, particularly the ammonia assimilation cycle. Tolerance is most likely due to a more strategic defensive and metabolic readjustment, resulting from the activation of specific defence‐related genes and to the downregulation of the abscisic acid pathway. [ABSTRACT FROM AUTHOR]

The impact of elevated CO2 (eCO2) on soybean productivity is essential to the global food supply because it is the world's leading source of vegetable proteins. This study aimed to understand the yield responses and nutritional impact under free‐air CO2 enrichment (FACE) conditions of soybean genotypes. Here we report that grain yield increased by 46.9% and no reduction in harvest index was observed among soybean genotypes. Elevated CO2 improved the photosynthetic carbon assimilation rate, leaf area, plant height, and aboveground biomass at vegetative and pod filling stages. Besides the positive effects on yield parameters, eCO2 differentially affected the overall grain quality. The levels of calcium (Ca), phosphorous (P), potassium (K), magnesium (Mg), manganese (Mn), iron (Fe), boron (B), and zinc (Zn) grain minerals decreased by 22.9, 9.0, 4.9, 10.1, 21.3, 28.1, 18.5, and 25.9% under eCO2 conditions, respectively. Soluble sugars and starch increased by 9.1 and 16.0%, respectively, phytic acid accumulation increased by 8.1%, but grain protein content significantly decreased by 5.6% across soybean genotypes. Furthermore, the antioxidant activity decreased by 36.9%, but the total phenolic content was not affected by eCO2 conditions. Genotypes, such as Winsconsin Black, Primorskaja, and L‐117, were considered the most responsive to eCO2 in terms of yield enhancement and less affected in the nutritional quality. Our results confirm the existence of genetic variability in soybean responses to eCO2, and differences between genotypes in yield improvement and decreased sensitivity to eCO2 in terms of grain quality loss could be included in future soybean selection to enable adaptation to climate change. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency chlorosis (IDC) affects the growth of several crops, especially when growing in alkaline soils. The application of synthetic Fe‐chelates is one of the most commonly used strategies in IDC amendment, despite their associated negative environmental impacts. In a previous work, the Fe‐chelate tris(3‐hydroxy‐1‐(H)‐2‐methyl‐4‐pyridinonate) iron(III) [Fe(mpp)3] has shown great potential for alleviating IDC in soybean (Glycine max) in the early stages of plant development under hydroponic conditions. Herein, its efficacy was verified under soil conditions in soybean grown from seed to full maturity. Chlorophyll levels, plant growth, root and shoot mineral accumulation (K, Mg, Ca, Na, P, Mn, Zn, Ni, and Co) and FERRITIN expression were accessed at V5 phenological stage. Compared to a commonly used Fe chelate, FeEDDHA, supplementation with [Fe(mpp)3] led to a 29% higher relative chlorophyll content, 32% higher root biomass, 36% higher trifoliate Fe concentration, and a twofold increase in leaf FERRITIN gene expression. [Fe(mpp)3] supplementation also resulted in increased accumulation of P, K, Zn, and Co. At full maturity, the remaining plants were harvested and [Fe(mpp)3] application led to a 32% seed yield increase when compared to FeEDDHA. This is the first report on the use of [Fe(mpp)3] under alkaline soil conditions for IDC correction, and we show that its foliar application has a longer‐lasting effect than FeEDDHA, induces efficient root responses, and promotes the uptake of other nutrients. [ABSTRACT FROM AUTHOR]

Ligands of the 3‐hydroxy‐4‐pyridinone (3,4‐HPO) class were considered eligible to formulate new Fe fertilizers for Iron Deficiency Chlorosis (IDC). Soybean (Glycine max L.) plants grown in hydroponic conditions and supplemented with Fe‐chelate [Fe(mpp)3] were significantly greener, had increased biomass, and were able to translocate more iron from the roots to the shoots than those supplemented with an equal amount of the commercially available chelate [FeEDDHA]. To understand the influence of the structure of 3,4‐HPO ligand on the role of the Fe‐chelate to improve Fe‐uptake, we investigated and report here the effect of Fe‐chelates ([Fe(mpp)3], [Fe(dmpp)3], and [Fe(etpp)3]) in addressing IDC. Chlorosis development was assessed by measurement of morphological parameters, quantification of chlorophyll and Fe, and other micronutrient contents, as well as measurement of enzymatic activity (FCR) and gene expression (FRO2, IRT1, and Ferritin). All [Fe(3,4‐HPO)3] chelates were able to provide Fe to plants and prevent IDC but with a different efficiency depending on the ligand. We hypothesize that this may be related with the distinct physicochemical characteristics of ligands and complexes, namely, the diverse hydrophilic–lipophilic balance of the three chelates. To test the hypothesis, we performed an EPR biophysical study using liposomes prepared from a soybean (Glycine3 max L.) lipid extract and spin probes. The results showed that the most effective chelate [Fe(mpp)3] shows a preferential location close to the surface while the others prefer the hydrophobic region inside the bilayer. Significance statement: The 3‐hydroxy‐4‐pyridinone Fe‐chelates, [Fe(mpp)3], [Fe(dmpp)3], and [Fe(etpp)3], were all able to provide Fe to plants and prevent IDC. Efficacy is dependent on the structure of the ligand. From an EPR biophysical study using spin probes and liposomes, prepared from a soybean lipid extract, we hypothesize that this may be related with the distinct preferential location close to the surface or on the hydrophobic region of the lipid bilayer. [Fe(mpp)3] provide higher amounts of Fe in the leaves. [ABSTRACT FROM AUTHOR]

BACKGROUND The aim of this study was to identify biochemical markers to predict internal browning disorders ( IBD) in 'Rocha' pear. Fruits from five orchards were stored for 45 days under cold air followed by 100 days in browning-inducing controlled atmosphere ( CA) conditions (1 kPa O2 + 10 kPa CO2). RESULTS Relationships between concentrations of ethanol ( EtOH), acetaldehyde ( AcDH) and ascorbic acid ( AA), activities of peroxidase ( POX) and polyphenoloxidase ( PPO) and IBD incidence were established. The partial least square ( PLS) model using the most promising markers, EtOH and AcDH, explained 89% of the variance in IBD incidence, whereas the univariate models based on the same markers explained between 89 and 94%. In contrast, the models based on AA levels and AA depletion rate only explained 57 and 82% of the variance in IBD incidence respectively. Model validation confirmed the robustness of EtOH for the prediction ( R2 = 0.91, RMSE = 11.1) and allowed proposing a threshold level of 30 µL EtOH L−1 above which IBD may occur. Using this threshold value, the storage time limit associated with the occurrence of the first IBD symptoms was predicted with an acceptable RMSE of 9 days. CONCLUSION This work clearly identifies biochemical IBD markers for 'Rocha' pear and shows that dynamic changes in ethanol concentration during the beginning of storage may be used to predict IBD development. Therefore the results presented herein represent a major step forward in the prediction of IBD in 'Rocha' pear. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The aim of this study was to identify biochemical markers to predict internal browning disorders ( IBD) in 'Rocha' pear. Fruits from five orchards were stored for 45 days under cold air followed by 100 days in browning-inducing controlled atmosphere ( CA) conditions (1 kPa O2 + 10 kPa CO2). RESULTS Relationships between concentrations of ethanol ( EtOH), acetaldehyde ( AcDH) and ascorbic acid ( AA), activities of peroxidase ( POX) and polyphenoloxidase ( PPO) and IBD incidence were established. The partial least square ( PLS) model using the most promising markers, EtOH and AcDH, explained 89% of the variance in IBD incidence, whereas the univariate models based on the same markers explained between 89 and 94%. In contrast, the models based on AA levels and AA depletion rate only explained 57 and 82% of the variance in IBD incidence respectively. Model validation confirmed the robustness of EtOH for the prediction ( R2 = 0.91, RMSE = 11.1) and allowed proposing a threshold level of 30 µL EtOH L−1 above which IBD may occur. Using this threshold value, the storage time limit associated with the occurrence of the first IBD symptoms was predicted with an acceptable RMSE of 9 days. CONCLUSION This work clearly identifies biochemical IBD markers for 'Rocha' pear and shows that dynamic changes in ethanol concentration during the beginning of storage may be used to predict IBD development. Therefore the results presented herein represent a major step forward in the prediction of IBD in 'Rocha' pear. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]