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The escalation in the intensity, frequency, and duration of high-temperature (HT) stress is currently unparalleled, which aggravates the challenges for crop production. Yet, the stage-dependent responses of reproductive organs to HT stress at the morphological, physiological, and molecular levels remain inadequately explored in pivotal staple crops. This review synthesized current knowledge regarding the mechanisms by which HT stress induces abnormalities and aberrations in reproductive growth and development, as well as by which it alters the morphology and function of florets, flowering patterns, and the processes of pollination and fertilization in maize (Zea mays L.). We identified the stage-specific sensitivities to HT stress and accurately defined the sensitive period from a time scale of days to hours. The microspore tetrad phase of pollen development and anthesis (especially shortly after pollination) are most sensitive to HT stress, and even brief temperature spikes during these stages can lead to significant kernel loss. The impetuses behind the heat-induced impairments in seed set are closely related to carbon, reactive oxygen species, phytohormone signals, ion (e.g. Ca2+) homeostasis, plasma membrane structure and function, and others. Recent advances in understanding the genetic mechanisms underlying HT stress responses during maize sexual reproduction have been systematically summarized. [ABSTRACT FROM AUTHOR]

The impact of water deficit severity and the specific growth stages at which water stress is applied have been found to have significant implications for both tomato yield and fruit quality. Recent findings have highlighted the influence of water deficits during the reproductive phase on tomato fruit quality. This study aimed to assess the effects of deficit irrigation on tomato fruit quality and overall plant productivity. Cherry tomatoes (Solanum lycopersicum var. cerasiforme) were grown in a greenhouse from August to November 2022. Three distinct watering regimes were implemented: Daily watering (T1), watering every 3 days (T2) and watering every 7 days (T3), starting from the flowering stage and continuing through subsequent plant development stages. The mean soil metric potentials (SMP) were -4.9, -29.7 and -52.8 kPa for T1, T2 and T3, respectively. Various traits of fruit size, fruit biomass, total soluble solids (TSS), water content, glucose content and lycopene content were measured. Additionally, the overall plant biomass and root-to-shoot ratio were evaluated. The results revealed that traits of the fruit size, such as diameter, length, volume and fresh weight, were most favorable when plants were subjected to the T2 watering regime, while higher and lower watering frequencies led to smaller fruit sizes. Interestingly, the TSS concentration had the most pronounced response to drought stress, indicating increased fruit sweetness. However, the fruit water content, glucose content and lycopene content remained unaffected by the different watering regimes. Furthermore, plants subjected to the T3 with the minimum SMP at -196.4 kPa exhibited enhanced development of the root system, prioritizing resource acquisition such as water and mineral nutrients over shoot components. In conclusion, this study provided valuable insights for agricultural practitioners, offering a range of alternatives that can inform optimal irrigation strategies that effectively enhance the quality of cherry tomato yields. [ABSTRACT FROM AUTHOR]

Flowering regulation is a reflection of plant self-adaptation to the environment and is the main determinant of plant yield. The quantitative trait loci (QTL) mapping of agronomic traits associated with the flowering stage of Agropyron Gaertn. was conducted using a cross-pollinated (CP) hybrid population with a total of 113 plant lines between A. mongolicum Keng Z2098 and A. cristatum (L.) Gaertn. Z1842 under four different environmental conditions and the genetic map constructed of 1,023 single-nucleotide polymorphism (SNP) markers. The results showed that 28 QTLs were detected on seven linkage groups. Each QTL explained 0.39–18.46% of the phenotypic variation, with a logarithm of odds (LOD) value ranging from 2.52 to 30.51. Specifically, QTLs were identified for various characteristics: one QTL identified for tiller number (TN), two for plant height (PH), three for days-to-flowering (DTF), five for flag leaf length (FLL), three for flag leaf width (FLW), three for spike length (SL), eight for spike width (SW), one for spikelet number per spike (SNS), and two for flower number per spike (FNS). One stable QTL controlling the SW was detected in two environments at the same loci and was located at 26 cM (Marker29867–Marker26864) on chromosome 5, showing a positive genetic effect. The two QTL enrichment regions suggested that the QTLs might contribute to trait correlation or pleiotropic genes. The identified QTLs potentially offer utility for marker-assisted breeding selection. [ABSTRACT FROM AUTHOR]

Nymphaea 'Eldorado', a valuable water lily, is a well-known fragrant plant in China. Studying the temporal and spatial characteristics of the floral components of this plant can provide a reference for the further development and utilization of water lily germplasm resources. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC-MS) was used to explore the types and relative contents of floral components at different flowering stages (S1: bud stage; S2: initial-flowering stage; S3: full-flowering stage; S4: end-flowering stage) and in different floral organs of N. 'Elidorado', combined with the observation of the microscopic structure of petals. A total of 60 volatile organic compounds (VOCs) were detected at different flowering stages, and there were significant differences in floral VOCs at different flowering stages and in different flower organs. The volatile compounds of N. 'Eldorado' can be divided into seven chemical classes,, namely, alkenes, alcohols, esters, aldehydes, ketones, alkanes, and others; the most common were alkenes and alkanes. A total of 39, 44, 47, and 42 volatile compounds were detected at S1, S2, S3, and S4. The VOCs present in high concentrations include benzaldehyde, benzyl alcohol, benzyl acetate, trans-α-bergamotene, α-curcumene, cis-α-farnesene, and so on. The types and total contents of volatiles at the full-flowering stage were higher than at other flowering stages. Comparing the VOCs in different parts of flower organs, it was found that the contents of alcohols, esters, and aldehydes were greatest in the petals, the alkenes in stamens were abundant with a relative content of up to 54.93%, and alkanes in the pistil were higher than in other parts. The types and total contents of volatiles in the stamens of N. 'Eldorado' were higher than those in other flower organs; they were the main part releasing fragrance. The observation of petal microstructure revealed that the size and quantity of the papillae on the epidermises of petals, the number of intracellular plastids, and the aggregates of floral components (osmophilic matrix granules) were significantly higher at the full-flowering stage than at the other flowering stages. This study suggested the main flowering stage and location at which the floral VOCs are released by N. 'Eldorado' and provided a reference for guiding the breeding of this water lily, exploring genetic patterns and developing related products. [ABSTRACT FROM AUTHOR]

Introduction: Lentil is a rich source of protein, fiber, minerals, antioxidants, folate, zinc, selenium, iron, and low amounts of fat and carbohydrates. Increasing water shortage and drought stress will be a major threat to global lentil production. The present study was conducted to determine the morphophysiological traits and grain of yield under normal and drought stress conditions, investigate tolerance indices and identify drought tolerance in some lentil genotypes. Materials and methods: In this experiment, twenty - four lentil genotypes were evaluated in the research farm of Shahrekord Faculty of Agriculture in two drought-stress environments and the normal conditions of the region in two separate randomized complete block designs with three replications experiments. In the 50% flowering stage, drought stress was done by completely stopping irrigation for the genotypes. Sampling was done at the end of the growing season. In this experiment, morphophysiological and yield traits were measured. Results and discussion: The results of composite data analysis showed that the effect of environment, genotype and the interaction effect of genotype × environment were significant on most traits. The share of these sources of variation in diversity of triats was different and environment placed on the most role in the diversity of seed yield (55.27%), genotype in the diversity of 100 seed weight (64.6%) and the number of single seed pods (53.9%). Seed yield in normal agricultural conditions has a positive correlation with most of the traits. In addition, under stress conditions, more traits had a significant correlation with grain yield. STI and GMP indices were highly correlated with yield in both environments and these indices can be used to select the superior genotype. Examining the main components of the indicators showed that the first component and two components justify 97.66% of the changes, the first component was introduced as a semi-tolerant component and the second component as a tolerant component. The results of the cluster analysis put the genotypes in three general groups. The results of cluster analysis based on STI and GMP indices put the genotypes in three separate groups. Conclusion: One of the main goals of production programs in arid and semi-arid regions is the screening of germplasm in different stages of plant growth. The results of the present research showed that drought stress in the reproductive stage reduces the morphophysiological traits and yield of lentil genotypes. Based on the results of seed yield, Kimia genotype with the lowest yield loss is known as the tolerant variety and C113 variety with the highest yield loss is known as the sensitive variety. Based on the results of seed yield, Kimia genotype with the lowest yield loss is known as the tolerant variety and C113 variety with the highest yield loss is known as the sensitive variety. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.), a forage legume known for its moderate salt–alkali tolerance, offers notable economic and ecological benefits and aids in soil amelioration when cultivated in saline–alkaline soils. Nonetheless, the limited stress resistance of alfalfa could curtail its productivity. This study investigated the salt tolerance and growth-promoting characteristics (in vitro) of four strains of plant growth-promoting rhizobacteria (PGPR) that were pre-selected, as well as their effects on alfalfa at different growth stages (a pot experiment). The results showed that the selected strains belonged to the genera Priestia (HL3), Bacillus (HL6 and HG12), and Paenibacillus (HG24). All four strains exhibited the ability to solubilize phosphate and produce indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Among them, except for strain HG24, the other strains could tolerate 9% NaCl stress. Treatment with 100 mM NaCl consistently decreased the IAA production levels of the selected strains, but inconsistent changes (either enhanced or reduced) in terms of phosphate solubilization, ACC deaminase, and exopolysaccharides (EPS) production were observed among the strains. During the various growth stages of alfalfa, PGPR exhibited different growth-promoting effects: at the seedling stage, they enhanced salt tolerance through the induction of physiological changes; at the flowering stage, they promoted growth through nutrient acquisition. The current findings suggest that strains HL3, HL6, and HG12 are effective microbial inoculants for alleviating salt stress in alfalfa plants in arid and semi-arid regions. This study not only reveals the potential of indigenous salt-tolerant PGPR in enhancing the salt tolerance of alfalfa but also provides new insights into the mechanisms of action of PGPR. [ABSTRACT FROM AUTHOR]

High temperature around flowering has a serious impact on the growth and development of maize. However, few maize genes related to flowering under heat stress have been confirmed, and the regulatory mechanism is unclear. To reveal the molecular mechanism of heat tolerance in maize, two maize hybrids, ZD309 and XY335, with different heat resistance, were selected to perform transcriptome and metabolomics analysis at the flowering stage under heat stress. In ZD309, 314 up-regulated and 463 down-regulated differentially expressed genes (DEGs) were detected, while 168 up-regulated and 119 down-regulated DEGs were identified in XY335. By comparing the differential gene expression patterns of ZD309 and XY335, we found the "frontloaded" genes which were less up-regulated in heat-tolerant maize during high temperature stress. They included heat tolerance genes, which may react faster at the protein level to provide resilience to instantaneous heat stress. A total of 1062 metabolites were identified via metabolomics analysis. Lipids, saccharides, and flavonoids were found to be differentially expressed under heat stress, indicating these metabolites' response to high temperature. Our study will contribute to the identification of heat tolerance genes in maize, therefore contributing to the breeding of heat-tolerant maize varieties. [ABSTRACT FROM AUTHOR]

Background: Salinity is a major limitation for rice farming due to climate change. Since salt stress adversely impact rice plants at germination, seedling, and reproductive stages resulting in poor crop establishment and reduced grain yield, enhancing salt tolerance at these vulnerable growth stages will enhance rice productivity in salinity prone areas. Methods and results: An introgression line (ILs) population from a cross between a high yielding cultivar 'Cheniere' and a salt tolerant donor 'TCCP' was evaluated to map quantitative trait loci (QTLs) for traits associated with salt tolerance at germination, seedling, and reproductive stages. Using a genotyping-by-sequencing based high density SNP linkage map, a total of 7, 16, and 30 QTLs were identified for five germination traits, seven seedling traits, and ten reproductive traits, respectively. There was overlapping of QTLs for some traits at different stages indicating the pleiotropic effects of these QTLs or clustering of linked genes. Candidate genes identified for salt tolerance were OsSDIR1 and SERF for the seedling stage, WRKY55 and OsUBC for the reproductive stage, and MYB family transcription factors for all three stages. Gene ontology analysis revealed significant GO terms related to nucleotide binding, protein binding, protein kinase activity, antiporter activity, active transmembrane transporter activity, calcium-binding protein, and F- box protein interaction domain containing protein. Conclusions: The colocalized QTLs for traits at different growth stages would be helpful to improve multiple traits simultaneously using marker-assisted selection. The salt tolerant ILs have the potential to be released as varieties or as pre-breeding lines for developing salt tolerant rice varieties. [ABSTRACT FROM AUTHOR]

Context. As global temperatures increase, heat waves of >30°C for at least 3 days are projected to become more frequent during reproductive development of wheat, causing reductions in grain yield. Breeding for tolerance is difficult under field conditions owing to the unpredictable timing and intensity of natural heat events and the narrow developmental windows of sensitivity. Aims. We report on a series of experiments designed to explore genetic variability for floret sterility induced by natural heat waves in the field by targeting a sensitive development stage. Methods. Our method involved sowing late, and the use of auricle distance to identify main tillers exposed to heat events at a sensitive developmental stage (booting). Key results. Substantial genetic variation was found for tolerance of grain set to natural heat waves, with a broad-sense heritability estimate of 0.94 for heat-exposed stems compared with 0.72 for non-stressed controls. An auricle distance of 1-3 cm was established as a phenotypic marker for tagging stems at the sensitive stage of development, and the optimal number of spikes to assess was determined as 10-15 per plot. A validation study with durum lines previously classified as tolerant/intolerant under glasshouse conditions showed agreement in ranking of genotypes at the extremes of tolerance. Conclusions. We demonstrate that it is possible to screen wheat genotypes for stage-specific tolerance to natural heat waves in the field. Implications. The protocol described could provide a low-cost method for evaluating heat tolerance in wheat, with relevance to commercial field production conditions. The approach allows tolerance to be assessed at a single stage of reproductive development, which should allow greater heritability in field assessments. [ABSTRACT FROM AUTHOR]

Introduction: Legumes are the second most important food source in the world after cereals. Beans are very effective in stabilizing nitrogen and fertility of agricultural soil due to their coexistence with bacteria, and large amounts of nitrogen are added to the soil every year after harvesting this plant. Environmental factors, especially drought stress conditions, play a major role in the quantitative and qualitative characteristics of crops. Reduction of available water, especially at the beginning of the flowering stage and the occurrence of drought stress in legumes, while reducing the rate of vegetative growth and shortening the stage of reproductive growth has a negative effect on grain quality. Nutritional deficiencies in plants cause them to be sensitive to environmental stresses. Excessive use of chemical fertilizers in agriculture to provide the phosphate needed by plants has always caused adverse environmental effects and has led to a decline in the quality of agricultural products. However, the use of biofertilizers has many benefits over chemical fertilizers. Therefore, considering the importance of the above, the purpose of this study is to investigate the role of biofertilizer and phosphorus fertilizer on bean plant elements in drought stress conditions. Materials and Methods: An experimental split-split plot with three replications was performed to investigate the effect of bio-fertilizer and phosphate fertilizer application on nutrient uptake in roots, stems, and seeds of beans under drought stress in season 2016-2017 in Ilam city. Treatments included three levels of irrigation interruption (non-stress conditions, cut off in flowering stage, and cut off in pod formation stage) in the main plot and three levels of phosphate fertilizer (25, 50, and 100 kg. ha1) and application and non-application of biofertilizer. Drought stress treatment in this experiment was performed by stopping irrigation in two stages of full flowering and podding. All phosphorus fertilizer related to each treatment was applied to the ground at once during cultivation. After germination and establishment of the plants in the 2-4 leaf stage, the plants were thinned and one plant was kept in each pile. Weed control was done manually in two stages before flowering. Results and Discussion: The results showed that the highest nitrogen concentrations in roots, stems, and seeds under non-stress conditions (full irrigation) were 1.12, 1.77, and 3.19%, respectively. Also, the lowest nitrogen concentrations of roots, stems, and seeds in the cut-off flowering stage were 0.92, 1.46, and 2.63%, respectively. The mean comparison results showed that the highest grain nitrogen concentration in non-stress conditions (full irrigation) was 3.19%, which increased by 21.29% compared to the cut-off irrigation treatment at the flowering stage. The results showed that the highest concentration of root potassium in the conditions of irrigation interruption in the flowering stage and biofertilizer application was 2.63% and the lowest was obtained in the treatment without stress and non-application of biofertilizer (2%). The average comparison results showed that the highest concentration of potassium in the stem was obtained in the condition of cut off irrigation in the flowering stage at the rate of 4.35% and the lowest amount was obtained in the full irrigation at the rate of 3.60%. The results showed that in the treatment of biofertilizer application, the highest concentration of phosphorus in the grain was 0.265 percent, while the lowest in the treatment of nonapplication of biofertilizer was 0.226 percent. Conclusion:The application of phosphate fertilizer significantly increased the absorption of elements. The application of biofertilizer also significantly increased the concentration of nitrogen, potassium, and phosphorus in bean plants. In general, the results of this study showed that the use of biofertilizer and phosphate fertilizer could reduce the adverse effects of drought stress on bean plants and increase the absorption of elements in bean organs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Yield loss and toxin contamination caused by wheat Fusarium head blight (FHB) have always been a worldwide concern. Cultivating disease‐resistant varieties and fungicide application are effective measures to control FHB. The comprehensive control technology system for FHB and toxin contamination of wheat in Anhui Province needs further improvement. This study compared the control efficacy of different wheat varieties, fungicides and application times on wheat FHB and deoxynivalenol (DON) contamination, and the dynamic change of DON accumulation after application. RESULTS: Among the 93 main wheat varieties in Anhui Province, the disease‐resistant and low‐toxic wheat variety "Ningmai 26" was more suitable for planting in the central part of Anhui Province. At the same time, "Yangmai 22" was used for subsequent experiments. The field efficacy trials of different fungicides showed that 30% prothioconazole oil dispersion (OD) had the highest control efficacy on FHB and DON contamination, reaching 94.33 and 77.49%, respectively. The study on the optimum application time of prothioconazole showed that the 0–20% flowering stage was the key point of DON control. The survey of the dynamic changes of DON accumulation showed that prothioconazole could significantly reduce the level of DON accumulation while inhibiting the accumulation rate of DON. At the same time, the control fungicide carbendazim increased the level of DON contamination. CONCLUSION: This study will provide excellent germplasm resources for cultivating disease‐resistant and low‐toxic wheat varieties, and provide a theoretical reference for establishing a collaborative prevention and control system of disease control and toxin reduction. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Nymphaea ‘Eldorado’, a valuable water lily, is a well-known fragrant plant in China. Studying the temporal and spatial characteristics of the floral components of this plant can provide a reference for the further development and utilization of water lily germplasm resources. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC-MS) was used to explore the types and relative contents of floral components at different flowering stages (S1: bud stage; S2: initial-flowering stage; S3: full-flowering stage; S4: end-flowering stage) and in different floral organs of N. ‘Elidorado’, combined with the observation of the microscopic structure of petals. A total of 60 volatile organic compounds (VOCs) were detected at different flowering stages, and there were significant differences in floral VOCs at different flowering stages and in different flower organs. The volatile compounds of N. ‘Eldorado’ can be divided into seven chemical classes,, namely, alkenes, alcohols, esters, aldehydes, ketones, alkanes, and others; the most common were alkenes and alkanes. A total of 39, 44, 47, and 42 volatile compounds were detected at S1, S2, S3, and S4. The VOCs present in high concentrations include benzaldehyde, benzyl alcohol, benzyl acetate, trans-α-bergamotene, α-curcumene, cis-α-farnesene, and so on. The types and total contents of volatiles at the full-flowering stage were higher than at other flowering stages. Comparing the VOCs in different parts of flower organs, it was found that the contents of alcohols, esters, and aldehydes were greatest in the petals, the alkenes in stamens were abundant with a relative content of up to 54.93%, and alkanes in the pistil were higher than in other parts. The types and total contents of volatiles in the stamens of N. ‘Eldorado’ were higher than those in other flower organs; they were the main part releasing fragrance. The observation of petal microstructure revealed that the size and quantity of the papillae on the epidermises of petals, the number of intracellular plastids, and the aggregates of floral components (osmophilic matrix granules) were significantly higher at the full-flowering stage than at the other flowering stages. This study suggested the main flowering stage and location at which the floral VOCs are released by N. ‘Eldorado’ and provided a reference for guiding the breeding of this water lily, exploring genetic patterns and developing related products.

In order to find out the freezing injury index of Camellia oleifera, a Camellia variety named “Tiecheng No. 1”was used as test material, a artificial control experiment was carried out at the Camellia oleifera base in Changde city, Hunan province in 2020 and 2021, respectively. Taking the natural state as a control, several low-temperature freezers were used to set low-temperature treatments with different intensities at −6℃ to 3℃(or −8℃ to 2℃) for 4 hours, and the Camellia oleifera branches at the flowering stage were placed in the freezers in a non-isolated way. 7 days after treatment, the morphological changes of Camellia oleifera were observed, and the rate of falling flower (fruit) and photosynthetic parameters were determined. The results showed that the morphological indicators of Camellia oleifera, falling flowers (fruit) rate and the light response parameters were clearly changed by low temperature. As the temperature decreased, the symptoms of freezing injury became more obvious, falling flowers (fruit) rate increased, while the maximum net photosynthetic rate, apparent quantum efficiency and saturation irradiation decreased. According to the symptoms of freezing damage and the response of the above physiological indicators to different low temperatures, it was determined that −2℃ was the upper limit of freezing damage of Camellia oleifera during flowering period, −6℃ was the critical temperature for significant aggravation of freezing damage, and −8℃ was the critical temperature for serious freezing damage. It was concluded that the slight freezing injury index of Camellia oleifera during flowering period was: −6℃＜daily minimum temperature ≤−2℃, and the moderate freezing injury index was:−8℃＜daily minimum temperature≤−6 ℃, and the severe freezing damage was: daily minimum temperature ≤−8℃. [ABSTRACT FROM AUTHOR]

High temperatures during flowering stage affects the seed setting in maize and thereby result in significant yield penalties in recent changing climate era. Based on the daily maximum temperature data of the maize growing season from 1971 to 2019 at the surface meteorological observatory in Henan Province of China and maize observation data at the agricultural meteorological observatory, an early warning grade of high temperatures during the summer maize flowering stage was constructed. The daily maximum temperature of the summer maize flowering stage was ≥ 32 °C as the critical threshold of high temperature disaster, and ≥ 35 °C as the threshold of high temperature disaster. The number of high temperature days (HD) ≥ 32 °C and ≥ 35 °C during 10 days of the summer maize flowering stage were counted. The sequence of high temperature days of summer maize flowering stage was constructed and its normal distribution characteristics were verified. The quartile value of the normal distribution sequence was selected as the threshold value of high temperature in different grades, and the high temperature heat damage in the summer maize flowering stage was divided into three early warning meteorological grades. The index verification of the early warning meteorological grade was carried out by using the observation data of kernel number per ear in the agricultural meteorological station for maize. The results showed that the three grade indexes corresponding to the number of high temperature days with daily maximum temperature ≥ 32 °C were: 3 ≤ HD < 5 (Grade I), 5 ≤ HD < 7 (Grade II), and HD ≥ 7 (Grade III) and the three grade indexes corresponding to high temperature days ≥ 35 °C were: 2 ≤ HD < 3 (Grade I), 3 ≤ HD < 5 (Grade II), HD ≥ 5 (Grade III). The constructed indexes were verified as follows, the number of high temperature days ≥ 32 °C at about 90% stations was significantly negatively correlated with the number of maize grains per ear, and 74% stations which the number of high temperature days ≥ 35 °C was significantly negatively correlated with the number of maize grains per ear. Applying this index to evaluate the high temperature risk in the flowering period, we can indicate that the high temperature risk had trend of increasing gradually from north to south. In conclusion, the constructed high temperature warning meteorological grade index during the flowering stage could accurately reflect the damage grade of maize during the flowering stage. [ABSTRACT FROM AUTHOR]

Sesame (Sesamum indicum L.) is a tropical oilseed crop that is also cultivated in arid and semi-arid environments, where drought occurs frequently. The objective of this study was to assess the performance of some sesame mutants, developed by our team through EMS-mutagenesis in 2020, under well-watered conditions and restricted irrigation by analyzing certain morphological, physiological, and agronomic attributes. The experiment was conducted in pots under field conditions according to a completely randomized design with three replications. The stress was simulated by suspending and reducing irrigation to 50% of the control, from the beginning of flowering until the appearance of the first capsule. The results showed variation attributable to genotypes, water regimes and their interaction was significant for all parameters studied, except the number of seeds per capsule. The mutants "ML2-5", "ML2-72" and "ML2-37" were found to be the most tolerant to drought, exhibiting lowest stress sensitivity index and highest seed yield were associated with higher proline content in the leaves, more developed root system, higher chlorophyll content, and higher stomatal conductance than the rest of the mutants studied. This is the first report of sesame mutant lines with such high tolerance to drought during flowering. They could be used for developing high-performing cultivars with tolerance to drought during the flowering stage. The number of capsules per plant and stomatal conductance can be considered selection criteria to improve water-stress tolerance in sesame. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of nitrogen (N) application on the grain yield and antioxidant response in fragrant rice under high soil temperature during the flowering stage. A pot experiment was conducted with two conventional fragrant rice varieties, i.e., super rice variety (Yuxiangyouzhan) and non-super rice variety (Xiangyaxiangzhan) grown under two nitrogen application levels (ZN, 0 g N per 12 kg soil and AN, 1.75 g N per 12 kg soil) as well as two temperature levels (Ambient soil temperature, AT and high soil temperature, HT). The grain yield and antioxidant defense of super and non-super fragrant rice were evaluated. The results showed that significant differences in grain yield and antioxidant defense parameters with regard to the variety, temperature treatment, nitrogen treatment, and their interactions were detected. Compared with ZN, the AN treatment significantly increased the grain yield of Yuxiangyouzhan and Xiangyaxiangzhan by 55.06% and 13.32%, respectively, under AT conditions and by 32.62% and 29.19%, respectively, under HT condition. Besides, the antioxidant parameters varied by variety and temperature treatment at AN treatment. Nitrogen application had a significant effect on Superoxide dismutase (SOD) activity and Catalase (CAT) activity in the leaves. The results of this study confirmed that the N application could regulate grain yield and antioxidant capacity of fragrant rice at flowering stage under HT condition. [ABSTRACT FROM AUTHOR]

BackgroundSalt stress, a major plant environmental stress, is a critical constraint for rice productivity. Dissecting the genetic loci controlling salt tolerance in rice for improving productivity, especially at the flowering stage, remains challenging. Here, we conducted a genome-wide association study (GWAS) of salt tolerance based on exome sequencing of the Thai rice accessions.ResultsPhotosynthetic parameters and cell membrane stability under salt stress at the flowering stage; and yield-related traits of 104 Thai rice (Oryza sativa L.) accessions belonging to the indica subspecies were evaluated. The rice accessions were subjected to exome sequencing, resulting in 112,565 single nucleotide polymorphisms (SNPs) called with a minor allele frequency of at least 5%. LD decay analysis of the panel indicates that the average LD for SNPs at 20 kb distance from each other was 0.34 (r2), which decayed to its half value (~ 0.17) at around 80 kb. By GWAS performed using mixed linear model, two hundred loci containing 448 SNPs on exons were identified based on the salt susceptibility index of the net photosynthetic rate at day 6 after salt stress; and the number of panicles, filled grains and unfilled grains per plant. One hundred and forty six genes, which accounted for 73% of the identified loci, co-localized with the previously reported salt quantitative trait loci (QTLs). The top four regions that contained a high number of significant SNPs were found on chromosome 8, 12, 1 and 2. While many are novel, their annotation is consistent with potential involvement in plant salt tolerance and in related agronomic traits. These significant SNPs greatly help narrow down the region within these QTLs where the likely underlying candidate genes can be identified.ConclusionsInsight into the contribution of potential genes controlling salt tolerance from this GWAS provides further understanding of salt tolerance mechanisms of rice at the flowering stage, which can help improve yield productivity under salinity via gene cloning and genomic selection.

All plants contain varying levels of phenolic acids (metabolites) thus playing an important role in resistance mechanisms as constituents of cell walls, as constitutive antimicrobial compounds of plants or induced in response to infection against many diseases, in particular fusarium head blight caused by Fusarium species. To this end, the objective of this research was to study the variation in phenolic acid composition during the kinetics of filling wheat grains, in order to determine the best variety resistant to fusarium head blight. For this purpose, free and bound phenolic analyses were carried out by HPLC-DAD on five durum wheat varieties at the stage 5 to 8 days after the flowering stage (early grains). We showed that at the level of the samples analyzed, several phenolic acids were present at different concentrations, but others were absent [ cis-ferulic acid (free phenolic acid), and sinapic acid (bound phenolic acid)]. The results also showed that the content of bound phenolic acids was much higher than that of free phenolic acids in all varieties. In addition, these phenolic acids existed in free soluble form or were mostly present in insoluble form bound to cell walls. For free acids, the results showed that significant amounts of transferulic acid were detected in comparison to all free phenolic acids (56.72 μg · g –1 DM for G10). For bound acids, ferulic acid is the main bound phenolic acid which has much higher levels (4913.92 μg · g –1 DM for G1), followed by p-coumaric acid (3098.99 μg · g–1 DM for G1). Moreover, the sum of monomers (bound acids) was much higher than that of dehydrodiferulic acids (DiFA).

Drought is a major crop production constraint worldwide. Some legume crops are known for their ability to resist water deficit stress. This study evaluated the responses of bambara groundnut (Vigna subterranea (L.) Verdc) and groundnut (Arachis hypogaea (L.) to soil water deficit stress. The experiment was set as a split-plot randomized complete block design. Three bambara groundnut landraces: viz DodR, NALBAM 4 and S19-3, and one groundnut variety, MNANJE, were assigned to subplots with three water regimes assigned to main plots (regime one: irrigated throughout the growing period, regime two: water deficit stress was imposed at the start of flowering to the end of first flush flowering, regime three: water was withheld during the pod development). Water deficit stress increased proline content by 123% in stressed plots. The highest (174%) and lowest (89%) proline increases were evident in the genotypes MNANJE and NALBAM 4, respectively. Water deficit decreased stomatal conductance, transpiration rate and photosynthetic rate, with MNANJE and S19-3 showing the smallest percentage decrease in most of the traits. This suggests that the two genotypes are drought resistant. The variations observed among landraces could be exploited to breed resilient varieties for cultivation in drought-prone areas, ultimately improving food security. [ABSTRACT FROM AUTHOR]

High temperature around flowering has a serious impact on the growth and development of maize. However, few maize genes related to flowering under heat stress have been confirmed, and the regulatory mechanism is unclear. To reveal the molecular mechanism of heat tolerance in maize, two maize hybrids, ZD309 and XY335, with different heat resistance, were selected to perform transcriptome and metabolomics analysis at the flowering stage under heat stress. In ZD309, 314 up-regulated and 463 down-regulated differentially expressed genes (DEGs) were detected, while 168 up-regulated and 119 down-regulated DEGs were identified in XY335. By comparing the differential gene expression patterns of ZD309 and XY335, we found the “frontloaded” genes which were less up-regulated in heat-tolerant maize during high temperature stress. They included heat tolerance genes, which may react faster at the protein level to provide resilience to instantaneous heat stress. A total of 1062 metabolites were identified via metabolomics analysis. Lipids, saccharides, and flavonoids were found to be differentially expressed under heat stress, indicating these metabolites’ response to high temperature. Our study will contribute to the identification of heat tolerance genes in maize, therefore contributing to the breeding of heat-tolerant maize varieties.

Loquat is a high-value fruit tree with medicine and fruit homology. Loquat flowers with special fragrance, strong cold resistance and rich in various bioactive components, are valuable agricultural auxiliary products and have been widely used for making floral teas and beverages in recent years. In this study, we found the concentration of active components increased from the floral buds to initial flowers along with flower development, the bioactives of initial flowers were the richest in four flowering stages, and loquat flowers contained major volatile components such as alcohols, aldehydes and esters, which are the source of fragrance. When extract with hot water, the most efficient method was 80 °C for 30 min or boiling water within 2 h. For Baijiu (56% Vol), the best solid-to-liquid ratio was 3:100 (Dry flower: Baijiu) in 6–12 h. Baijiu achieved higher bioactive content than water extraction, the amygdalin concentration in Baijiu reached 0.3 mg/mL.

Populations of the same plant species living in different locations but flowering at different times may vary in pollinator availability and floral traits. However, the spatial and temporal links between floral traits and pollination are rarely included in single studies. In this study, three populations of an alpine lousewort, Pedicularis rhinanthoides Schrenk subsp. tibetica (Bonati) Tsoong, were surveyed to detect the variations in floral traits and pollinator activity. We hypothesized that floral divergence was spatio-temporally correlated with pollen limitation (PL) in relation to pollinators. Sampled plants from each population were divided into three groups, according to flowering stage: early, peak, and late. Pollen-supplementation experiments and investigations into pollinators, reproductive success, and floral traits were conducted on the plants from the different flowering stages and across the populations. Our results showed that the extent of PL varies across populations and among flowering stages. Populations in which more pollinators were recorded displayed a lower extent of PL. Furthermore, the temporal differences in PL showed a similar pattern for the three populations; the plants from the peak flowering stage suffered slighter PL than those from the other two stages. Nevertheless, some of the floral traits displayed similar spatial and temporal patterns to the PL, while the others only varied among the populations spatially. The results indicated that the performance of floral traits in a particular spatial–temporal situation shows they are well adapted to the corresponding pollination environment, which might help plants to optimize their reproductive fitness under different abiotic factors. [ABSTRACT FROM AUTHOR]

Current agricultural methodologies are vulnerable to erratic climate and are dependent on cost-intensive fertilization to ensure high yields. Sustainable practices should be pursued to ensure food security. Phaseolus vulgaris L. is one of the most produced legumes worldwide and may be an alternative to reduce the environmental impact of meat production as a reliable source of high-quality protein. Plant growth-promoting rhizobacteria (PGPR) are emerging as a sustainable option to increase agricultural production. To understand the dynamics between plants and microorganisms, the culturable microbiota of bean roots was isolated and identified at distinct stages of plant development (early and late vegetative growth, flowering, and pod) and root compartments (rhizoplane, endosphere, and nodules). Diversity and abundance of bacteria associated with root compartments differed throughout the plant life cycle. Bacterial plant growth promotion (PGP) and protection abilities (indole-3-acetic acid production, siderophore synthesis, and antifungal activity) were assessed and associated with plant phenology, demonstrating that among the bacteria associated with plant roots, several strains had an active role in the response to plant biological needs at each stage. Several strains stood out for their ability to display one or more PGP traits, being excellent candidates for efficient stage-specific biostimulants for application in precision agriculture. [ABSTRACT FROM AUTHOR]

Aphid is one of the main insect pests of wheat in the flowering stage, so timely and effective control of wheat aphids plays an important role in ensuring wheat yield. The crop protection Unmanned Aerial Vehicle (UAV) is widely used in the control of wheat pests and diseases nowadays. In order to screen out the suitable operation parameters of the crop protection UAV to control the wheat aphids, this study conducted wheat aphid distribution investigation tests and droplet distribution tests. With the P20 electric four-rotor crop protection UAV (Guangzhou Jifei Technology Co., Ltd., Guangzhou, China) as the test equipment, four levels of flight speed (FS: 3, 4, 5, 6 m/s) and three levels of flight height (FH: 1.5, 2, 2.5 m) were combined as operation parameters, tests were carried out to compare the density and uniformity of droplet coverage, and the wheat aphid control tests were carried out by using the optimized operation parameters. The results of the wheat aphid distribution investigation test showed that aphids mainly distributed in the lower layer of the wheat plant canopy, accounting for more than 90.61%. The results of the droplet distribution test showed that with the increase in FS and FH, the coverage density and the droplet distribution uniformity in the upper and lower layers of wheat showed a downward trend under the condition of considering the boundary overlap of spraying width (SW) in multi-routes. Through the comparison of operation efficiency and droplet distribution quality, two combinations of parameters A1 (FS: 3 m/s, FH: 1.5 m) and B1 (FS: 4 m/s, FH: 1.5 m) were selected for the aphid control effect test. The results of the control test showed that the average control effect of A1 (92.05%) on aphids was 10.3% higher than that of B1 (81.75%) 7 days after pesticide application, which indicated that improving the droplet distribution uniformity in the lower layer of wheat could significantly improve the control effect of aphids. This study result could provide reference for the same type of crop protection UAV to control the same type of wheat diseases and insect pests in the same growing stage. [ABSTRACT FROM AUTHOR]

• Sanqi flowers have a higher quality under organic vs conventional management. • The flavonoid biosynthesis pathway was positively influenced by organic management. • The full blooming stages is the best time to harvest the Sanqi flowers. The simulative habitat cultivation of Panax notoginseng (Sanqi) under pine forests using organic management (OM) enhances the quality of Sanqi roots. However, the impact of the OM on the quality of Sanqi flowers remains unknown. The Sanqi flowers cultivated under OM compared with those cultivated under CM (conventional management) exhibited higher levels of flavonoids, saponins, and polysaccharides, as well as dry/fresh weight. Principal component analysis demonstrated that metabolites were predominantly influenced by the cultivation patterns followed by the flowering stage. Several of the differentially abundant metabolites and expressed genes were upregulated in Sanqi flowers cultivated under OM. The flavonoid biosynthesis pathway was highly affected by the cultivation systems and flowering stages, mediated by the essential genes C4H, HCT, C3′H, DFR, and FLS. Flavonoid levels peaked at full bloom, indicating that this is the optimum stage for harvesting Sanqi flowers. Our findings are of great value for developing optimal cultivation and harvest practices. [ABSTRACT FROM AUTHOR]

Rice is highly vulnerable to salt stress at both seedling and flowering stage. While research efforts largely focused on seedling stage salinity tolerance, flowering stage salt tolerance studies are limited. Development of rice cultivars with salt tolerance at both stages will enhance rice productivity in salt affected farmlands. In the present study, two introgression line (IL) populations of a salt-tolerant landrace 'Nona Bokra (N)' were developed in the genetic backgrounds of two U.S. cultivars 'Cheniere (C)' and 'Jupiter (J)' and were evaluated for elucidation of the genetic basis of agronomically important traits at flowering stage and development of salt tolerant pre-breeding lines. Evaluation of both sets of ILs (JN-ILs and CN-ILs) under saline (EC = 8 dSm−1) environment led to identification of a total of 33 QTLs for seven different yield and yield component traits impacted by salt stress. Majority of large-effect QTLs for traits such as panicle length (qPL1.1JN), spikelet sterility (qSS1.1JN), thousand-grain weight (qTGW1.1JN), days to flowering (qDFF1.1CN), and plant height (qPH1.1CN) were located on chromosome 1. Some candidate genes present within the major effect QTL regions include potassium channel OsKAT1, NAC domain-containing protein, potassium transporters, and photosensitive leaf rolling 1. Comparison of the results with earlier reports on seedling stage suggested a different set of genes controlling salt tolerance at both stages. In addition, pre-breeding lines with improved flowering stage salinity tolerance were identified. These pre-breeding rice lines will accelerate fine mapping, map-based cloning, and pyramiding of desirable alleles for both flowering and seedling stage salt tolerance through marker assisted selection. [ABSTRACT FROM AUTHOR]

Plants developing into the flowering stage undergo major physiological changes. Because flowers are reproductive tissues and resource sinks, strategies to defend them may differ from those for leaves. Thus, this study investigates the defences of flowering plants by assessing processes that sustain resistance (constitutive and induced) and tolerance to attack. We exposed the annual plant Brassica nigra to three distinct floral attackers (caterpillar, aphid and bacterial pathogen) and measured whole‐plant responses at 4, 8 and 12 days after the attack. We simultaneously analysed profiles of primary and secondary metabolites in leaves and inflorescences and measured dry biomass of roots, leaves and inflorescences as proxies of resource allocation and regrowth. Regardless of treatments, inflorescences contained 1.2 to 4 times higher concentrations of primary metabolites than leaves, and up to 7 times higher concentrations of glucosinolates, which highlights the plant's high investment of resources into inflorescences. No induction of glucosinolates was detected in inflorescences, but the attack transiently affected the total concentration of soluble sugars in both leaves and inflorescences. We conclude that B. nigra evolved high constitutive rather than inducible resistance to protect their flowers; plants additionally compensated for damage by attackers via the regrowth of reproductive parts. This strategy may be typical of annual plants. Results show that flowering Brassica nigra protect their inflorescences with constitutive resistance rather than with inducible resistance, and compensate for floral dammage with early changes in primary metabolism and regrowth. Metabolic profiles reflected high resource investment into reproduction. [ABSTRACT FROM AUTHOR]

Chili (Capsicum annuum L.) is a horticultural plant susceptible to high-temperature stress. This research studied how agronomic and physiological characteristics of chili decline due to high temperature and determined the threshold value of temperature decreasing 50% of its yield. The experiment layout followed a randomized design, consisting of five temperature stress levels (in the growth chamber), namely, 31°C (daily temperature as a control), 33°C, 35°C, 37°C, and 39°C, with an exposure duration of 10 h. The temperature stress started when the plant reached the flowering phase. The plant parameters observed included agronomic and physiological characteristics. The study results showed that high-temperature decreased production significantly with the decline in all agronomic and physiological traits. The threshold temperature at 32.86°C has reduced the production of chili plants by 50% compared with the control. The study found that an increase in temperature of 2°C for 10 h in the flowering phase reduces chili production by 68.78%, and temperature stress at a maximum of 39°C for 10 h during flowering reduces chili production up to 87.52%. Hence, based on the study results, future research on chili should focus on developing varieties that are adaptive to high temperatures. [ABSTRACT FROM AUTHOR]

Heat stress at the flowering stage significantly impacts rice grain yield, yet the number of identified genes associated with rice heat tolerance at this crucial stage remains limited. This study focuses on elucidating the function of the heat-induced gene reduced heat stress tolerance 1 (OsRHS). Overexpression of OsRHS leads to reduced heat tolerance, while RNAi silencing or knockout of OsRHS enhances heat tolerance without compromising yield, as assessed by the seed setting rate. OsRHS is localized in the cytoplasm and mainly expressed in the glume and anther of spikelet. Moreover, OsRHS was found to interact with the HSP protein cHSP70-4, and the knockout of cHSP70-4 resulted in increased heat tolerance. Complementation assays revealed that the knockout of cHSP70-4 could restore the compromised heat tolerance in OsRHS overexpression plants. Additional investigation reveals that elevated temperatures can amplify the bond between OsRHS and cHSP70-4 within rice. Furthermore, our findings indicate that under heat stress conditions during the flowering stage, OsRHS plays a negative regulatory role in the expression of many stress-related genes. These findings unveil the crucial involvement of OsRHS and cHSP70-4 in modulating heat tolerance in rice and identify novel target genes for enhancing heat resilience during the flowering phase in rice., (© 2024 John Wiley & Sons Ltd.)

All plants contain varying levels of phenolic acids (metabolites) thus playing an important role in resistance mechanisms as constituents of cell walls, as constitutive antimicrobial compounds of plants or induced in response to infection against many diseases, in particular fusarium head blight caused by Fusarium species. To this end, the objective of this research was to study the variation in phenolic acid composition during the kinetics of filling wheat grains, in order to determine the best variety resistant to fusarium head blight. For this purpose, free and bound phenolic analyses were carried out by HPLC-DAD on five durum wheat varieties at the stage 5 to 8 days after the flowering stage (early grains). We showed that at the level of the samples analyzed, several phenolic acids were present at different concentrations, but others were absent [cis-ferulic acid (free phenolic acid), and sinapic acid (bound phenolic acid)]. The results also showed that the content of bound phenolic acids was much higher than that of free phenolic acids in all varieties. In addition, these phenolic acids existed in free soluble form or were mostly present in insoluble form bound to cell walls. For free acids, the results showed that significant amounts of transferulic acid were detected in comparison to all free phenolic acids (56.72 µg · g-1 DM for G10). For bound acids, ferulic acid is the main bound phenolic acid which has much higher levels (4913.92 µg · g-1 DM for G1), followed by p-coumaric acid (3098.99 µg · g-1 DM for G1). Moreover, the sum of monomers (bound acids) was much higher than that of dehydrodiferulic acids (DiFA). [ABSTRACT FROM AUTHOR]

Global climate change has increased the frequency of extreme climate events, and their effects on the nutritional quality, especially on amino acids in rice, have not been quantified. The data from a 3-year low temperature stress (LTS) experiment including two rice varieties (Huaidao 5 and Nanjing 46), seven minimum/maximum temperature levels (one optimal 21/27°C and six LTS levels from 17/23 to 6/12°C), and three LTS durations (3, 6, and 9 days) after flowering, revealed significant interactive effects of LTS at different stages, durations, and temperature levels on the content and accumulation of amino acids. LTS increased rice total amino acid content, while decreasing its accumulation, with higher sensitivities to LTS at the flowering stage than at the grain filling stage. In most treatments, the lysine (the first limiting amino acid) and phenylalanine content were increased under LTS at early and peak flowering stages but decreased at the grain filling stage in both varieties, and only leucine content was increased at all three stages after flowering, while the content of other essential amino acids differed among the two varieties. With an increase of 1°C·d per day in the accumulated cold degree days, the relative content of the essential amino acids was increased by 0.01–0.41%, depending on the rice variety and growth stage. Our results suggest that LTS can improve nutritional quality of amino acids of rice grains in terms of amino acids content, especially at flowering stage. These results provide critical insights for assessing the potential impact of extreme climates on the nutrient quality of rice under future climate change. [ABSTRACT FROM AUTHOR]

Accurate representation of photosynthetic capacity and its seasonal variations is critical for modeling carbon sequestration of cropland ecosystems through photosynthesis. Previous studies indicated that the maximum carboxylation rate at 25 °C (Vcmax25) is the key determinant of photosynthetic capacity and can be mapped according to leaf nitrogen (N) and chlorophyll (Chl) contents. However, whether relationships of Vcmax25 with leaf nitrogen and chlorophyll contents in cropland ecosystems change over the whole growing season remain unclear. To address this question, we conducted intensive field campaigns in winter wheat and paddy rice farmlands of Eastern China, with leaf Vcmax25, the maximum electron transport rate at 25 °C (Jmax25), N, and Chl measured every 7 to 10 days from the tillering stage to maturity. Results showed that Vcmax25 and Jmax25 varied significantly during the growing seasons and maximized at flowering stages. For both winter wheat and paddy rice, Chla (Chl content at the area unit) showed significantly different relationships with Vcmax25 pre- and post- flowering while Na (N content at the area unit) did not. When different empirical models were used for pre- flowering and post- flowering stages, Vcmax25 estimated from Chla was closer to observations (R2 = 0.875, RMSE = 9.479 µmol m−2 s−1) than that estimated from Na (R2 = 0.565, RMSE = 17.718 µmol m−2 s−1). The findings in this study imply that the combination of remotely sensed leaf Chla content and phenology would improve the mapping of Vcmax25 for crops at regional and even global scales.

Global climate change has increased the frequency of extreme climate events, and their effects on the nutritional quality, especially on amino acids in rice, have not been quantified. The data from a 3-year low temperature stress (LTS) experiment including two rice varieties (Huaidao 5 and Nanjing 46), seven minimum/maximum temperature levels (one optimal 21/27°C and six LTS levels from 17/23 to 6/12°C), and three LTS durations (3, 6, and 9 days) after flowering, revealed significant interactive effects of LTS at different stages, durations, and temperature levels on the content and accumulation of amino acids. LTS increased rice total amino acid content, while decreasing its accumulation, with higher sensitivities to LTS at the flowering stage than at the grain filling stage. In most treatments, the lysine (the first limiting amino acid) and phenylalanine content were increased under LTS at early and peak flowering stages but decreased at the grain filling stage in both varieties, and only leucine content was increased at all three stages after flowering, while the content of other essential amino acids differed among the two varieties. With an increase of 1°C·d per day in the accumulated cold degree days, the relative content of the essential amino acids was increased by 0.01–0.41%, depending on the rice variety and growth stage. Our results suggest that LTS can improve nutritional quality of amino acids of rice grains in terms of amino acids content, especially at flowering stage. These results provide critical insights for assessing the potential impact of extreme climates on the nutrient quality of rice under future climate change.

Climate change has resulted in a continuous increase in the frequency and intensity of chilling events in cold regions. In Northeast China, chilling at the booting and flowering stages negatively affects japonica rice grain yield. In this field experiment study, we conducted a 2‐year temperature‐controlled experiment to investigate the effects of chilling temperature and duration applied at the booting and flowering stages on japonica rice. The results showed that chilling at the two study stages delayed the rice phenology and decreased the grain yield. In particular, japonica rice was more sensitive to chilling at the booting stage than at the flowering stage. The rice grain yield was reduced by more as the chilling temperature decreased and the chilling duration increased. As for the yield components, the spikelet fertility and grain number per spike were more sensitive to chilling at the booting stage than at the flowering stage. Variations in the grain yield per plant were primarily contributed by the differences in spikelet fertility and grain number per spike, especially the spikelet fertility. In addition, cooling degree days showed statistically significant negative correlations with grain yield per plant, grain number per spike and spikelet fertility. For every 10°C·day increase in CDD at the booting (flowering) stage, the grain yield per plant, spikelet fertility and grain number per spike decreased by 7.1%, 6.2% and 3.4% (3.9%, 5.0% and 1.2%) respectively. As the spikelet fertility and grain number per spike decreased, the sink capacity decreased as well with the increasing of allocated assimilation to the stem and leaf while decreasing the assimilation allocated to the panicle. Increasing cooling degree days at the booting and flowering stages increased the allocations of assimilation to the stem and leaf. As a result, less assimilation was allocated to the panicle. This study suggests that breeding cultivars to improve the spikelet fertility and grain number per spike could help to minimize the potential rice grain yield loss due to the increase in chilling events occurring at the booting and flowering stages. [ABSTRACT FROM AUTHOR]

Drought is one of the most critical environmental factors constraining maize production. When it occurs at the flowering stage, serious yield losses are caused, and often, the damage is irretrievable. In this study, anthesis to silk interval (ASI), plant height (PH), and ear biomass at the silking date (EBM) of 279 inbred lines were studied under both water-stress (WS) and well-water (WW) field conditions, for three consecutive years. Averagely, ASI was extended by 25.96%, EBM was decreased by 17.54%, and the PH was reduced by 12.47% under drought stress. Genome-wide association studies were carried out using phenotypic values under WS, WW, and drought-tolerance index (WS-WW or WS/WW) and applying a mixed linear model that controls both population structure and relative kinship. In total, 71, 159, and 21 SNPs, located in 32, 59, and 12 genes, were significantly (P < 10−5) associated with ASI, EBM, and PH, respectively. Only a few overlapped candidate genes were found to be associated with the same drought-related traits under different environments, for example, ARABIDILLO 1, glycoprotein, Tic22-like, and zinc-finger family protein for ASI; 26S proteasome non-ATPase and pyridoxal phosphate transferase for EBM; 11-ß-hydroxysteroid dehydrogenase, uncharacterised, Leu-rich repeat protein kinase, and SF16 protein for PH. Furthermore, most candidate genes were revealed to be drought-responsive in an association panel. Meanwhile, the favourable alleles/key variations were identified with a haplotype analysis. These candidate genes and their key variations provide insight into the genetic basis of drought tolerance, especially for the female inflorescence, and will facilitate drought-tolerant maize breeding. [ABSTRACT FROM AUTHOR]

Salvia eremophila Boiss. is an endemic plant from Iran. Plant metabolites are directly affected by some environmental factors. In following, secondary metabolites and chemical compounds might be varied that this variation can lead to changes the pharmacological efficacies. To investigate chemical variation of the species in different natural habitats, the essential oils were extracted by hydro-distillation method using Clevenger apparatus. Comparative outcomes revealed considerable variations in the obtained oils and constitutions. The essential oil yield varied between 0.69-0.81% during full flowering stages. The essential oil analyses identified 14 compounds (86.7-94.1% of the total oil) among which α-pinene (48.7-52.7%) was the highest component in all studied populations. The other main compositions were borneol (11.5-14.7%), isobornyl acetate (9.1-10.8%), and trans-Caryophyllene (6.9-8.2%). Based on the present research it could be found that chemical variation of S. eremophila in the studied areas is considerable. Ghavam Abad was the best one in quality and quantity of the chemical compounds. [ABSTRACT FROM AUTHOR]

Abstract Heracleum persicum, commonly named Persian hogweed, is a principal native medicinal plant in Iran. Collecting H. persicum at the most appropriate growing stage is the key factor to achieve the high phytochemical quality to meet consumer's needs. In the present experiment, the aerial parts of this plant were harvested at up to six different developmental stages during the growing season to determine the phytochemical profiles. Our results indicated that the highest essential oil content was obtained in the mid‐mature seed stage (3.5%). The most elevated extract content was recorded in the floral budding stage (10.4%). In the vegetative stage, limonene (18.1%), in floral budding stage, caryophyllene (14.1%), anethole (14.6%), and β‐bisabolene (12.7%), in the full flowering stage, myristicin (15.0%), and hexyl butyrate (9.1%), in the early development of seeds stage, hexyl butyrate (32.1%), and octyl acetate (11.7%), in the mid‐mature seeds stage hexyl butyrate (38.8%), octyl acetate (14.5%), in the late‐mature/ripe seeds stage, hexyl butyrate (23.6%), and octyl acetate (10.5%) are recorded as the main components. The highest phenolic acids content was obtained in the floral budding stage (287.40 mg/g dried extract). The analysis of phenolic acids demonstrated cinnamic acid (8.0–225.3 mg/g extract), p‐coumaric acid (1.7–39.2 mg/g extract), p‐hydroxybenzoic acid (0.8–16.8 mg/g extract), and ferulic acid (2.4–15.8 mg/g extract) as the main phenolic acids. Cinnamic acid was found as the major phenolic compound in the vegetative stage following by floral budding, the full flowering stage, the early development of seeds, and late‐mature/ripe seeds stages. P‐coumaric acid was the most abundant phenolic compounds in the mid‐mature seeds stage. In this regard, the harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest. The results of this study can be used as a guideline for grower to obtain the highest possible amount of desirable metabolites, beneficial in both food and pharmaceutical industries as well as their undeniable economical benefits.

Plants phenology is extremely important tool for crop management, crop manipulation, and marketing. The objective of this research was to investigate the phenology and fruit quality of the several Annonaceae species under subtropical conditions of Homestead, Florida, USA. The study was carried out in an experimental sugar apple (Annona squamosa L.), orchard with cultivars: 'LeahReese', 'Lessard Thai' and 'Red' and the atemoya 'Gefner' (A. cherimola x A. squamosa L). Ten uniformly vigorous and healthy plants of each cultivar were selected. The fruit harvest period was similar for all the cultivars, except for sugar-apple 'LeahReese', which had the shortest harvest period of only 41 days. Multivariate analysis showed that 'Lessard Thai' and 'Red' sugar apple cultivars had smaller sizes and lower chemical quality. Cultivar "LeahResse" had the highest fruits, in addition, a strong correlation with the atemoya hybrid "Gefner". The sugar apples 'Lessard Thai' and 'Red' had similar phenology and had a 166-day pruning to harvest cycle. In contrast, 'LeahReese' sugar apple and 'Gefner' atemoya had significantly longer cycles of 182 and 196 days, respectively. The sugar apple 'LeahReese' had the best physical characteristics of the cultivars investigated, while the atemoya 'Gefner' had the best physiochemical characteristics and the longest shelf life. [ABSTRACT FROM AUTHOR]

Abstract Background This study was aimed at investigating the possible anti-inflammatory and cytotoxic effects of extracts from the flowering stage of C. argentea. This growth stage was chosen because of its high polyphenolic content and high antioxidant capacity. Methods Anti-inflammatory potential of the aqueous, acetone and methanol extracts of C. argentea was evaluated through the inhibition of nitric oxide production (LPS-induced) on stimulated macrophages (RAW 264.7), while MTT assay was used to assess cell viability with Silymarin as standard. Cytotoxicity of the plant extracts was evaluated on murine preadipocyte cell line (3 T3-L1) using the image-based method of two DNA-binding dyes; Hoechst 33342 and propidium iodide (PI) with melphalan as standard. Results Acetone extract exhibited moderate, dose-dependent anti-inflammatory activity with no significant toxicity to activated macrophages, however the aqueous and methanol extracts were unable to inhibit nitric oxide production at both trials. MTT assay and the toxicity assay revealed that the flowering stage extracts of C. argentea were not toxic to the RAW 264.7 macrophages and 3 T3-L1 cells at all the tested concentrations (0, 2, 50, 100 and 200 μg/mL). Conclusions These findings corroborate the traditional use of C. argentea for painful inflammatory conditions and encourage its possible use as lead for the development of novel, non-toxic, anti-inflammatory agents.

Drought is a major crop production constraint worldwide. Some legume crops are known for their ability to resist water deficit stress. This study evaluated the responses of bambara groundnut (Vigna subterranea (L.) Verdc) and groundnut (Arachis hypogaea (L.) to soil water deficit stress. The experiment was set as a split-plot randomized complete block design. Three bambara groundnut landraces: viz DodR, NALBAM 4 and S19-3, and one groundnut variety, MNANJE, were assigned to subplots with three water regimes assigned to main plots (regime one: irrigated throughout the growing period, regime two: water deficit stress was imposed at the start of flowering to the end of first flush flowering, regime three: water was withheld during the pod development). Water deficit stress increased proline content by 123% in stressed plots. The highest (174%) and lowest (89%) proline increases were evident in the genotypes MNANJE and NALBAM 4, respectively. Water deficit decreased stomatal conductance, transpiration rate and photosynthetic rate, with MNANJE and S19-3 showing the smallest percentage decrease in most of the traits. This suggests that the two genotypes are drought resistant. The variations observed among landraces could be exploited to breed resilient varieties for cultivation in drought-prone areas, ultimately improving food security.

Populations of the same plant species living in different locations but flowering at different times may vary in pollinator availability and floral traits. However, the spatial and temporal links between floral traits and pollination are rarely included in single studies. In this study, three populations of an alpine lousewort, Pedicularis rhinanthoides Schrenk subsp. tibetica (Bonati) Tsoong, were surveyed to detect the variations in floral traits and pollinator activity. We hypothesized that floral divergence was spatio-temporally correlated with pollen limitation (PL) in relation to pollinators. Sampled plants from each population were divided into three groups, according to flowering stage: early, peak, and late. Pollen-supplementation experiments and investigations into pollinators, reproductive success, and floral traits were conducted on the plants from the different flowering stages and across the populations. Our results showed that the extent of PL varies across populations and among flowering stages. Populations in which more pollinators were recorded displayed a lower extent of PL. Furthermore, the temporal differences in PL showed a similar pattern for the three populations; the plants from the peak flowering stage suffered slighter PL than those from the other two stages. Nevertheless, some of the floral traits displayed similar spatial and temporal patterns to the PL, while the others only varied among the populations spatially. The results indicated that the performance of floral traits in a particular spatial–temporal situation shows they are well adapted to the corresponding pollination environment, which might help plants to optimize their reproductive fitness under different abiotic factors.

Aphid is one of the main insect pests of wheat in the flowering stage, so timely and effective control of wheat aphids plays an important role in ensuring wheat yield. The crop protection Unmanned Aerial Vehicle (UAV) is widely used in the control of wheat pests and diseases nowadays. In order to screen out the suitable operation parameters of the crop protection UAV to control the wheat aphids, this study conducted wheat aphid distribution investigation tests and droplet distribution tests. With the P20 electric four-rotor crop protection UAV (Guangzhou Jifei Technology Co., Ltd., Guangzhou, China) as the test equipment, four levels of flight speed (FS: 3, 4, 5, 6 m/s) and three levels of flight height (FH: 1.5, 2, 2.5 m) were combined as operation parameters, tests were carried out to compare the density and uniformity of droplet coverage, and the wheat aphid control tests were carried out by using the optimized operation parameters. The results of the wheat aphid distribution investigation test showed that aphids mainly distributed in the lower layer of the wheat plant canopy, accounting for more than 90.61%. The results of the droplet distribution test showed that with the increase in FS and FH, the coverage density and the droplet distribution uniformity in the upper and lower layers of wheat showed a downward trend under the condition of considering the boundary overlap of spraying width (SW) in multi-routes. Through the comparison of operation efficiency and droplet distribution quality, two combinations of parameters A1 (FS: 3 m/s, FH: 1.5 m) and B1 (FS: 4 m/s, FH: 1.5 m) were selected for the aphid control effect test. The results of the control test showed that the average control effect of A1 (92.05%) on aphids was 10.3% higher than that of B1 (81.75%) 7 days after pesticide application, which indicated that improving the droplet distribution uniformity in the lower layer of wheat could significantly improve the control effect of aphids. This study result could provide reference for the same type of crop protection UAV to control the same type of wheat diseases and insect pests in the same growing stage.

Due to climate change, more temperature extremes are expected in the future, potentially endangering agricultural production. Chickpea (Cicer arietinum L.) is an important cool-season food legume grown worldwide; however, cold and heat episodes are major threats in chickpea production that cause considerable yield losses especially at the flowering stage. The aim of this study was to evaluate the physiological performance of contrasting chickpea genotypes during the flowering phase under cold and heat. Four chickpea genotypes (Desi, Eldorado, Acc#2 and Acc#7) with different temperature susceptibilities were treated for 3 days under cold (9/4 °C) and heat (38/33 °C). The results showed that cold stress reduced the maximum quantum efficiency of photosystem II (Fv/Fm) by 5%, net photosynthetic rate (PN) by 74%, and chlorophyll a+b content by 31% on average in all tested genotypes. Up to a 9-fold increase in the amount of starch was found in the leaves of plants under cold stress, indicating that carbohydrates strongly accumulated in chickpeas under cold stress. This helps to maintain the vegetative and generative organs and enable fast recovery. Under heat stress, chickpeas maintained Fv/Fm and PN, although chlorophyll a+b content decreased by 39% on average. Carbohydrates did not accumulate under heat in chickpeas; thereby, a reduction in biomass and reproductive organs took place. Genetic variation in response to cold and heat stress was detected among the tested flowering chickpea genotypes. Desi and Acc#2 were cold-sensitive candidates, and Eldorado was a cold-tolerant candidate, whereas Acc#7 and Acc#2 were heat-sensitive candidates, while Desi and Eldorado were heat-tolerant candidates. This study provides important knowledge on the physiological response of flowering chickpeas under cold and heat stress. This will benefit the identification of stress-tolerant chickpea genotypes to ensure high yields in the future climate.

Background and Aims Cold stress in rice (Oryza sativa) plants at the reproductive stage prevents normal anther development and causes pollen sterility. Tapetum hypertrophy in anthers has been associated with pollen sterility in response to cold at the booting stage. Here, we re-examined whether the relationships between anther abnormality and pollen sterility caused by cold stress at the booting stage in rice can be explained by a monovalent factor such as tapetum hypertrophy. Methods After exposing plants to a 4-d cold treatment at the booting stage, we collected and processed anthers for transverse sectioning immediately and at the flowering stage. We anatomically evaluated the effect of cold treatment on anther internal morphologies, pollen fertilities and pollen numbers in the 13 cultivars with various cold sensitivities. Key Results We observed four types of morphological anther abnormalities at each stage. Pollen sterility was positively correlated with the frequency of undeveloped locules, but not with tapetum hypertrophy as commonly believed. In cold-sensitive cultivars grown at low temperatures, pollen sterility was more frequent than anther morphological abnormalities, and some lines showed remarkably high pollen sterility without any anther morphological alterations. Most morphological anomalies occurred only in specific areas within large and small locules. Anther length tended to shorten in response to cold treatment and was positively correlated with pollen number. One cultivar showed a considerably reduced pollen number, but fertile pollen grains under cold stress. We propose three possible relationships to explain anther structure and pollen sterility and reduction due to cold stress. Conclusions The pollen sterility caused by cold stress at the booting stage was correlated with the frequency of entire locule-related abnormalities, which might represent a phenotypic consequence, but not a direct cause of pollen abortion. Multivalent factors might underlie the complicated relationships between anther abnormality and pollen sterility in rice. [ABSTRACT FROM AUTHOR]

Preliminary studies observed a lower growth activity during the vegetative stage with higher growth attributes at the pod-filling stage among the high nitrogen (N) utilisation efficiency (NUtE) oilseed rape (Brassica napus L.) genotypes, compared with the low NUtE genotypes. Therefore, we hypothesised that there would exist a critical growth stage when distinctive phenotypic traits are exhibited to regulate yield formation and NUE. A field experiment and a hydroponic culture were conducted to characterise the differences in shoot and root physiological indicators of the high and low NUtE oilseed rape genotypes at seedling, bud, bolting, flowering and pod-filling stages. We found that flowering was the critical period when the reverse growth habit occurred between high and low NUtE genotypes. The high NUtE genotypes displayed larger values of root traits, stronger N uptake kinetics parameters, higher activity of leaf glutamine synthetase (GS) and glutamate synthetase (GOGAT), larger SPAD values and net photosynthetic rate, ultimately leading to higher seed yield and NUE. Our results indicate that flowering is the critical growth stage to distinguish the high from low NUtE oilseed rape genotypes, and plant breeders may focus on selecting root and shoot phenotypic traits from flowering stage onwards to achieve both high yields and NUE for oilseed rape genotypes. [ABSTRACT FROM AUTHOR]

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