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Abstract The impact of biochar application on plant performance under drought stress necessitates a comprehensive understanding of biochar–soil interaction, root growth, and plant physiological processes. Therefore, pot experiments were conducted to assess the effects of biochar on plant responses to drought stress at the seedling stage. Two contrasting maize genotypes (drought-sensitive KN5585 vs. -tolerant Mo17) were subjected to biochar application under drought stress conditions. The results indicated that biochar application decreased soil exchangeable Na+ and Ca2+ contents while increased soil exchangeable K+ content (2.7-fold) and electrical conductivity (4.0-fold), resulting in an elevated leaf sap K+ concentration in both maize genotypes. The elevated K+ concentration with biochar application increased root apoplastic pH in the drought-sensitive KN5585, but not in the drought-tolerant Mo17, which stimulated the activation of H+-ATPase and H+ efflux in KN5585 roots. Apoplast alkalinization of the drought-sensitive KN5585 resulting from biochar application further inhibited root growth by 30.7%, contributing to an improvement in water potential, a reduction in levels of O2 –, H2O2, T-AOC, SOD, and POD, as well as the down-regulation of genes associated with drought resistance in KN5585 roots. In contrast, biochar application increased leaf sap osmolality and provided osmotic protection for the drought-tolerant Mo17, which was associated with trehalose accumulation in Mo17 roots. Biochar application improved sucrose utilization and circadian rhythm of Mo17 roots, and increased fresh weight under drought stress. This study suggests that biochar application has the potential to enhance plant drought tolerance, which is achieved through the inhibition of root growth in sensitive plants and the enhancement of osmotic protection in tolerant plants, respectively. Graphical Abstract

The impact of biochar application on plant performance under drought stress necessitates a comprehensive understanding of biochar–soil interaction, root growth, and plant physiological processes. Therefore, pot experiments were conducted to assess the effects of biochar on plant responses to drought stress at the seedling stage. Two contrasting maize genotypes (drought-sensitive KN5585 vs. -tolerant Mo17) were subjected to biochar application under drought stress conditions. The results indicated that biochar application decreased soil exchangeable Na+ and Ca2+ contents while increased soil exchangeable K+ content (2.7-fold) and electrical conductivity (4.0-fold), resulting in an elevated leaf sap K+ concentration in both maize genotypes. The elevated K+ concentration with biochar application increased root apoplastic pH in the drought-sensitive KN5585, but not in the drought-tolerant Mo17, which stimulated the activation of H+-ATPase and H+ efflux in KN5585 roots. Apoplast alkalinization of the drought-sensitive KN5585 resulting from biochar application further inhibited root growth by 30.7%, contributing to an improvement in water potential, a reduction in levels of O2–, H2O2, T-AOC, SOD, and POD, as well as the down-regulation of genes associated with drought resistance in KN5585 roots. In contrast, biochar application increased leaf sap osmolality and provided osmotic protection for the drought-tolerant Mo17, which was associated with trehalose accumulation in Mo17 roots. Biochar application improved sucrose utilization and circadian rhythm of Mo17 roots, and increased fresh weight under drought stress. This study suggests that biochar application has the potential to enhance plant drought tolerance, which is achieved through the inhibition of root growth in sensitive plants and the enhancement of osmotic protection in tolerant plants, respectively. Biochar application decreased soil exchangeable Na+ and Ca2+, but increased soil exchangeable K+ and electrical conductivity. Biochar increased apoplastic pH, but reduced root growth, stress damage and stress response during drought for the drought-sensitive KN5585. Biochar improved osmotic protection, trehalose accumulation, and fresh weight during drought for the drought-tolerant Mo17. [ABSTRACT FROM AUTHOR]

This study investigates the role of abscisic acid (ABA) in bolstering drought resistance in plants, employing "Panjiang Sophora viciifolia" as the subject. A simulated drought scenario was created using polyethylene glycol (PEG-6000) to examine the impact of varying drought intensities (0%, 5%, 20% PEG) and ABA concentrations (0, 10, 50, 100, 200 mg·L−1) on the germination and physiological parameters of Sophora viciifolia. The results showed that in the absence of ABA, the germination rate (GR), germination potential (GP), and germination index (GI) of S. viciifolia seeds initially increased and then decreased with escalating PEG-induced drought stress. At PEG-induced drought stress levels of 5% and 20%, the activities of peroxidase (POD) and catalase (CAT), along with the malondialdehyde (MDA) content, were significantly higher than in the control (CK) (p < 0.05). In response to drought stress, S. viciifolia seeds adapted by modulating germination behavior, augmenting the content of osmoregulatory substances, and boosting the activity of protective enzymes. The addition of ABA markedly enhanced GR, GE, GI, activities of POD, superoxide dismutase (SOD), and CAT, as well as the levels of MDA and proline (Pro) under drought conditions (p < 0.05). Relative to CK, low ABA concentrations (10–100 mg·L−1) resulted in increased GR, GP, GI, POD, SOD, CAT, MDA, and Pro levels; whereas, at a higher concentration (200 mg·L−1), although GR, GP, and GI decreased, POD, SOD, CAT, MDA, and Pro levels increased. Through principal component analysis and membership function comprehensive evaluation, it was determined that administering 50 mg·L−1 ABA was most effective in enhancing drought resistance in S. viciifolia seedlings. [ABSTRACT FROM AUTHOR]

Key message: This study not only provide a theoretical basis for screening drought-resistant yellowhorn rootstocks but also lay the foundation for the research on the drought resistance mechanism of yellowhorn. Drought is a major limiting factor in the production and cultivation of yellowhorn, an important woody oil species in China. It is important to select excellent drought-resistant rootstocks, and the current reproduction of rootstocks of yellowhorn is mainly through seed propagation. In this study, we analyzed the phenotypes, physiology and anatomy of the F1 generation of five yellowhorn varieties ('Zhongshi 1', 'Zhongshi 4', 'Zhongshi 7', 'Zhongshi 9' and 'Yuanda') which are currently the main promoted varieties of yellowhorn. The changes in physiological traits were used to comprehensively rank drought resistance by the membership function method. The results showed that the drought resistance of different varieties was in the order 'Zhongshi 9' > 'Zhongshi 4' > 'Yuanda' > 'Zhongshi 7' > 'Zhongshi 1'. In addition, we investigated the molecular signature of two yellowhorn varieties exhibiting a large difference in levels of drought resistance using transcriptome data. A total of 119 differentially expressed genes (DEGs) were found between the 2 yellowhorn varieties under drought stress. Based on KEGG analysis, DEGs were mostly enriched in three pathways. According to the correlation analysis between weighted gene co-expression network analysis (WGCNA) and physiological traits, a total of four co-expression networks with high correlation were constructed, and some hub genes of yellowhorn in response to drought stress were found. We carried out a comprehensive evaluation of yellowhorn drought tolerance based on parental lines. It solves the current problems faced in the breeding of yellowhorn and lays the foundation for studying the molecular mechanism of drought resistance in yellowhorn. [ABSTRACT FROM AUTHOR]

Drought stress is the primary abiotic factor affecting wheat growth, development, and yield formation. The application of plant growth-promoting rhizobacteria (PGPR) represents an environmentally sustainable approach to mitigate the impacts of drought stress on wheat. This study conducted field experiments using two winter wheat varieties, the drought-sensitive variety Jimai 22 and the drought-resistant variety Chang 6878, aiming to investigate the effects of Streptomyces pactum Act12 inoculation on photosynthetic characteristics, physiological parameters, and yield traits during the jointing, heading, and middle-filling stages under drought stress. The results revealed that drought stresses significantly reduced chlorophyll content, leaf area, biomass, and yield in wheat, while Act12 inoculation significantly increased chlorophyll content, photosynthetic efficiency, antioxidant enzyme activity such as superoxide dismutase (SOD) and peroxidase (POD), osmolyte content (proline and soluble proteins), and decreased malondialdehyde (MDA) content. These combined effects alleviated drought stress, resulting in increased biomass and yield in wheat. Under drought stress, an increase in leaf proline content of 13.53% to 53.23% (Jimai 22) and 17.17% to 43.08% (Chang 6878) was observed upon Act12 inoculation. Moreover, a decrease in MDA content was recorded of 15.86% to 53.61% (Jimai 22) and 13.47% to 26.21% (Chang 6878). Notably, there was a corresponding increase in yield of 11.78% (Jimai 22) and 13.55% (Chang 6878). In addition, grain quality analysis revealed a significant improvement in grain hardness with Act12 inoculation. Therefore, Act12 demonstrates the potential for enhancing the sustainable development of wheat production in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Durum wheat (Triticum durum Desf.) is a fundamental staple food for the countries of the Mediterranean basin. Climate change is predicted to cause a trend of increasing drought severity in this region in the near future, necessitating the improvement of durum wheat's resilience to drought stress. Using polyethylene glycol to simulate water scarcity, early vigour parameters in germinating seeds are quickly, easily and affordably assessed. Many screenings, however, only consider the seedling stage; consequently, genotypes identified as promising for cultivation in drought scenarios, may not show such features if drought appears in later phenological phases, as happens in Mediterranean climatic areas, generally prone to terminal drought. The correlation between drought stress resistance during the seedling stage (early vigour) and later stages in the life cycle is elusive due to the lack of scientific efforts. Here we used polyethylene glycol screening to classify fifty‐five tetraploid wheat accessions into three clusters (susceptible, medium resistant and highly resistant to drought), based on morpho‐physiological traits. These accessions included durum wheat cultivars and landraces, as well as ancestors like durum emmer wheat and wild emmer wheat. The results of the screenings were combined with subsequent pot experiments using nine randomly selected accessions, imposing terminal drought, and evaluating their performance. Principal component analysis was performed on data for net photosynthesis, stomatal conductance, transpiration and grain yield. Notably, the genotypes that performed best in the pot experiments were also those that performed well in the screening. Highly resistant candidates had in fact higher physiological and performance parameters than susceptible candidates. In summary, polyethylene glycol screening of germinating seeds resulted to be suitable to predictively evaluate drought resistance in tetraploid wheat accessions under terminal drought conditions, typical of Mediterranean climate zones. The reported data, thus evidence of how this inexpensive and simple method might be efficiently applied for large‐scale phenotyping. [ABSTRACT FROM AUTHOR]

Maize is an economically vital cereal crop. However, water deficiency can severely impact its productivity. Thus, it is necessary to implement an essential approach to increase maize yield while navigating the limitations imposed by scarce water supplies. The present study aimed to investigate whether foliar applications of silicon (Si) and zinc (Zn) could mitigate the adverse effects of water deficiency and improve maize growth and yield. Field experiments were conducted in Egypt during two growing seasons (2021–2022) under three irrigation regimes: full irrigation (ET0), moderate stress (ET1), and severe stress (ET2). The treatments comprised foliar sprays of Si, Zn, Si + Zn, and water control. Phenological, growth, physiological, chemical, and yield-related traits were assessed. Results showed that adequate irrigation (ET0) enhanced most parameters compared to water stress treatments. Under ET0, the combined silicon and zinc treatment resulted in the highest values for plant height, leaf area, chlorophyll content, grains per ear, kernel weight, ear size, and yield compared to other foliar treatments. Under drought stress (ET1, ET2), Si + Zn applications maintained superiority in mitigating yield losses. Proline accumulation was highest under severe stress (ET2) in the absence of foliar sprays, indicating greater drought impacts. Correlation analysis revealed positive associations of grain yield with ear size, leaf area, kernel weight, and biological yield. Cluster analysis separated irrigation regimes and visualized the consistently beneficial effects of Si + Zn across all water levels. Overall, the results demonstrate the synergistic potential of Si and Zn supplementation to sustain maize performance and yields under varying water availability.

This study aimed to evaluate the effects of plant growth-promoting Rhizobacteria (PGPR) treatments, B1, Azosprillium lipoferum Sp2 and B2, A. lipoferum Sp2 + Pseudomonas sp. SARS12, as well as inorganic nitrogen doses (60, 100, 140 and 180 kg N ha–1) on some soil physical characters, physiological, anatomical and yield parameters as well as nitrogen use efficiency (NUE) of wheat under water deficit stress. Results showed that water stress significantly decreased physiological characters such as chlorophyll content (6.7 and 9.8%) and relative water content (13.7 and 11.2%) in both seasons, respectively. Nevertheless, proline and malondialdehyde (MDA) were increased significantly (26.9, 12.3% and 90.2, 96.4%) in both seasons, respectively, as signals for water stress. The anatomical characteristics of flag leaves were negatively affected. Inoculation of wheat grains with PGPR significantly increased field capacity and RWC, adjusted enzymes' activity and thus improved the physiological and yield traits and NUE as well as improving the anatomical features of flag leaves. Moreover, the combination of integrated PGPR and 140 kg N ha−1 significantly improved grain yield and its components as well as grain N uptake in comparison to control treatments. In conclusion, PGPR improved wheat productivity and NUE; they are an eco-friendly and cost-effective approach for improving plant production, and reducing nutrient leaching hazards and the negative impact of water stress. [ABSTRACT FROM AUTHOR]

Legumes play a significant role in the alleviation of food insecurity, maintaining soil fertility, and achieving sustainable crop production under adverse environmental conditions. The increased demand in legume production contemplates that attention on the genetic improvement of these crops through various means such as genetic engineering and mutation breeding should take a centre stage in global agriculture. Therefore, this paper provides a succinct analysis of the currently available literature on morphological and physiological traits in polyploidised leguminous plants to counter the adverse effects of drought stress. The effects of colchicine on various morphological and physiological traits of polyploidised legumes compared to their diploid counterparts were examined. Numerous reports revealed variations in these traits, such as improved root and shoot growth, plant biomass, chloroplastidic content, protein, RNA, and DNA. The differences observed were also associated with the strong relationship between plant ploidy induction and colchicine application. Furthermore, the analysis indicated that polyploidisation remains dose-dependent and may be achievable within a shorter space of time as this antimitotic chemical interferes with chromosome separations in somatic plant cells. The efficiency of this process also depends on the advancement of treatment conditions (in vitro, in vivo, or ex vitro) and the successful regeneration of polyploidised plants for adaptation under drought stress conditions. As such, the improvement in metabolite profile and other essential growth characteristics serves as a clear indication that induced polyploidy needs to be further explored to confer resilience to environmental stress and improve crop yield under drought stress conditions in leguminous plants. [ABSTRACT FROM AUTHOR]

Faba bean is an important protein crop for food and feed worldwide and provides a range of advantages in crop rotations. Its limited use in modern agriculture is mainly due to the high fluctuations in yield. A well known limiting factor in most legumes, and particularly in faba bean, is the high sensitivity to water shortage, which is further aggravated by climate change. The present study was undertaken to exploit the genetic variation in drought stress response in a faba bean collection of 100 accessions with diverse origins and to assess selection criteria for identifying drought tolerant genotypes. Physiological, phenological and yield related traits evaluated under drought or water-sufficient conditions responded significantly to the end-terminated drought stress. Comparison of yield relations showed the advantage of using a stress tolerance index (STI) to identify genotypes combining high yield potential with high stress yield. With regard to physiological traits, SPAD (chlorophyll content) values were significantly related to yield as well as to STI, while the other traits also contributed to different extents to variation in yield formation. Among the yield related traits, seeds per plant proved to be the most important trait followed by pods per plant. Interestingly, the eight genotypes with the best STI performance use different strategies to cope with drought stress. [ABSTRACT FROM AUTHOR]

This study investigates the role of abscisic acid (ABA) in bolstering drought resistance in plants, employing “Panjiang Sophora viciifolia” as the subject. A simulated drought scenario was created using polyethylene glycol (PEG-6000) to examine the impact of varying drought intensities (0%, 5%, 20% PEG) and ABA concentrations (0, 10, 50, 100, 200 mg·L−1) on the germination and physiological parameters of Sophora viciifolia. The results showed that in the absence of ABA, the germination rate (GR), germination potential (GP), and germination index (GI) of S. viciifolia seeds initially increased and then decreased with escalating PEG-induced drought stress. At PEG-induced drought stress levels of 5% and 20%, the activities of peroxidase (POD) and catalase (CAT), along with the malondialdehyde (MDA) content, were significantly higher than in the control (CK) (p < 0.05). In response to drought stress, S. viciifolia seeds adapted by modulating germination behavior, augmenting the content of osmoregulatory substances, and boosting the activity of protective enzymes. The addition of ABA markedly enhanced GR, GE, GI, activities of POD, superoxide dismutase (SOD), and CAT, as well as the levels of MDA and proline (Pro) under drought conditions (p < 0.05). Relative to CK, low ABA concentrations (10–100 mg·L−1) resulted in increased GR, GP, GI, POD, SOD, CAT, MDA, and Pro levels; whereas, at a higher concentration (200 mg·L−1), although GR, GP, and GI decreased, POD, SOD, CAT, MDA, and Pro levels increased. Through principal component analysis and membership function comprehensive evaluation, it was determined that administering 50 mg·L−1 ABA was most effective in enhancing drought resistance in S. viciifolia seedlings.

Drought stress is the primary abiotic factor affecting wheat growth, development, and yield formation. The application of plant growth-promoting rhizobacteria (PGPR) represents an environmentally sustainable approach to mitigate the impacts of drought stress on wheat. This study conducted field experiments using two winter wheat varieties, the drought-sensitive variety Jimai 22 and the drought-resistant variety Chang 6878, aiming to investigate the effects of Streptomyces pactum Act12 inoculation on photosynthetic characteristics, physiological parameters, and yield traits during the jointing, heading, and middle-filling stages under drought stress. The results revealed that drought stresses significantly reduced chlorophyll content, leaf area, biomass, and yield in wheat, while Act12 inoculation significantly increased chlorophyll content, photosynthetic efficiency, antioxidant enzyme activity such as superoxide dismutase (SOD) and peroxidase (POD), osmolyte content (proline and soluble proteins), and decreased malondialdehyde (MDA) content. These combined effects alleviated drought stress, resulting in increased biomass and yield in wheat. Under drought stress, an increase in leaf proline content of 13.53% to 53.23% (Jimai 22) and 17.17% to 43.08% (Chang 6878) was observed upon Act12 inoculation. Moreover, a decrease in MDA content was recorded of 15.86% to 53.61% (Jimai 22) and 13.47% to 26.21% (Chang 6878). Notably, there was a corresponding increase in yield of 11.78% (Jimai 22) and 13.55% (Chang 6878). In addition, grain quality analysis revealed a significant improvement in grain hardness with Act12 inoculation. Therefore, Act12 demonstrates the potential for enhancing the sustainable development of wheat production in arid and semi-arid regions.

Creating xeric landscapes in lawns and prairies is a significant challenge and practical need in arid urban environments. This study examined the drought resistance of some C4 grass species for constructing urban lawns and prairies. A factorial experiment based on randomized complete block designs with four replications was conducted. Experimental treatments were two irrigation levels (100% and 50% Field Capacity (FC)) and five warm-season grass species (Andropogon gerardii Vitman, Sorghastrum nutans (L.) Nash, Panicum virgatum L., Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torr.). The effects of drought on physiological, morphological, and qualitative characteristics of the grass species were analyzed. Drought conditions induced a decrease in all the measured traits. However, fewer physiological, morphological, and qualitative characteristics were affected by drought stress on Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, compared to the other two species. Overall, warm-season grasses of Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, had greater adaptability to drought stress, making them promising C4 grass species for prairie or lawn landscaping in arid urban environments. Landscape professionals and decision-makers should consider using Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, as these were the most resilient grass species for drought-tolerant prairie landscaping schemes. Sorghastrum nutans and Panicum virgatum may be used as a second priority if a more diverse variety of grasses is required for drought-resilient prairie or lawn landscaping in arid cities. [ABSTRACT FROM AUTHOR]

Drought stress is one of the most important abiotic stresses limiting wheat production. To improve the growth and yield of wheat under drought stress, a factorial experiment was performed based on a randomized complete block design with three replicates in the research greenhouse of the University of Tehran. Experimental treatments included irrigation at two levels (well-watered and drought stress) and vitamin foliar application at four levels (control, thiamine, pyridoxine, and thiamine+pyridoxine). The results showed that drought stress reduced the relative water content of flag leaves by 21%. The use of vitamins increased the amount of this trait compared to the control treatment. The chlorophyll number (SPAD) of flag leaf increased under drought stress, but the use of vitamins had no significant effect on this trait. Drought stress had an increasing effect on leaf free proline content and foliar application of thiamine and its combination with pyridoxine, respectively, increased this trait by 53% and 32% compared to treatment without foliar application under drought stress conditions. Also, the percentage of electrolyte leakage and malondialdehyde content of flag leaf under drought stress increased by 31% and 103%, respectively. Vitamins reduced the amount of malondialdehyde and had no significant effect on the percentage of electrolyte leakage. Drought stress also reduced wheat grain and biological yields. Foliar application of vitamins showed an additive effect on these traits compared to the control treatment. The highest grain yield per plant was obtained in treatments of pyridoxine (1.1 g) and its combination with thiamine (1.2 g). [ABSTRACT FROM AUTHOR]

Faba bean is an important protein crop for food and feed worldwide and provides a range of advantages in crop rotations. Its limited use in modern agriculture is mainly due to the high fluctuations in yield. A well known limiting factor in most legumes, and particularly in faba bean, is the high sensitivity to water shortage, which is further aggravated by climate change. The present study was undertaken to exploit the genetic variation in drought stress response in a faba bean collection of 100 accessions with diverse origins and to assess selection criteria for identifying drought tolerant genotypes. Physiological, phenological and yield related traits evaluated under drought or water-sufficient conditions responded significantly to the end-terminated drought stress. Comparison of yield relations showed the advantage of using a stress tolerance index (STI) to identify genotypes combining high yield potential with high stress yield. With regard to physiological traits, SPAD (chlorophyll content) values were significantly related to yield as well as to STI, while the other traits also contributed to different extents to variation in yield formation. Among the yield related traits, seeds per plant proved to be the most important trait followed by pods per plant. Interestingly, the eight genotypes with the best STI performance use different strategies to cope with drought stress.

This study aimed to evaluate the effects of plant growth-promoting Rhizobacteria (PGPR) treatments, B1, Azosprillium lipoferum Sp2 and B2, A. lipoferum Sp2 + Pseudomonas sp. SARS12, as well as inorganic nitrogen doses (60, 100, 140 and 180 kg N ha–1) on some soil physical characters, physiological, anatomical and yield parameters as well as nitrogen use efficiency (NUE) of wheat under water deficit stress. Results showed that water stress significantly decreased physiological characters such as chlorophyll content (6.7 and 9.8%) and relative water content (13.7 and 11.2%) in both seasons, respectively. Nevertheless, proline and malondialdehyde (MDA) were increased significantly (26.9, 12.3% and 90.2, 96.4%) in both seasons, respectively, as signals for water stress. The anatomical characteristics of flag leaves were negatively affected. Inoculation of wheat grains with PGPR significantly increased field capacity and RWC, adjusted enzymes’ activity and thus improved the physiological and yield traits and NUE as well as improving the anatomical features of flag leaves. Moreover, the combination of integrated PGPR and 140 kg N ha−1 significantly improved grain yield and its components as well as grain N uptake in comparison to control treatments. In conclusion, PGPR improved wheat productivity and NUE; they are an eco-friendly and cost-effective approach for improving plant production, and reducing nutrient leaching hazards and the negative impact of water stress.

Legumes play a significant role in the alleviation of food insecurity, maintaining soil fertility, and achieving sustainable crop production under adverse environmental conditions. The increased demand in legume production contemplates that attention on the genetic improvement of these crops through various means such as genetic engineering and mutation breeding should take a centre stage in global agriculture. Therefore, this paper provides a succinct analysis of the currently available literature on morphological and physiological traits in polyploidised leguminous plants to counter the adverse effects of drought stress. The effects of colchicine on various morphological and physiological traits of polyploidised legumes compared to their diploid counterparts were examined. Numerous reports revealed variations in these traits, such as improved root and shoot growth, plant biomass, chloroplastidic content, protein, RNA, and DNA. The differences observed were also associated with the strong relationship between plant ploidy induction and colchicine application. Furthermore, the analysis indicated that polyploidisation remains dose-dependent and may be achievable within a shorter space of time as this antimitotic chemical interferes with chromosome separations in somatic plant cells. The efficiency of this process also depends on the advancement of treatment conditions (in vitro, in vivo, or ex vitro) and the successful regeneration of polyploidised plants for adaptation under drought stress conditions. As such, the improvement in metabolite profile and other essential growth characteristics serves as a clear indication that induced polyploidy needs to be further explored to confer resilience to environmental stress and improve crop yield under drought stress conditions in leguminous plants.

Deficit irrigation is a common approach in water-scarce regions to balance productivity and water use, whereas drought stress still occurs to various extents, leading to reduced physiological performance and a decrease in yield. Therefore, seeking a rapid and reliable method to identify wheat varieties with drought resistance can help reduce yield loss under water deficit. In this study, we compared ten wheat varieties under three deficit irrigation systems (W0, no irrigation during the growing season; W1, irrigation at jointing; W2, irrigation at jointing and anthesis). UAV thermal imagery, plant physiological traits [leaf area index (LAI), SPAD, photosynthesis (Pn), transpiration (Tr), stomatal conductance (Cn)], biomass and yield were acquired at different growth stages. Wheat drought resistance performance was evaluated through using the canopy temperature extracted from UAV thermal imagery (CT-UAV), in combination with hierarchical cluster analysis (HCA). The CT-UAV of W0 and W1 treatments was significantly higher than in the W2 treatment, with the ranges of 24.8–33.3 °C, 24.3–31.6 °C, and 24.1–28.9 °C in W0, W1 and W2, respectively. We found negative correlations between CT-UAV and LAI, SPAD, Pn, Tr, Cn and biomass under the W0 (R2 = 0.41–0.79) and W1 treatments (R2 = 0.22–0.72), but little relevance for W2 treatment. Under the deficit irrigation treatments (W0 and W1), UAV thermal imagery was less effective before the grain-filling stage in evaluating drought resistance. This study demonstrates the potential of ensuring yield and saving irrigation water by identifying suitable wheat varieties for different water-scarce irrigation scenarios. [ABSTRACT FROM AUTHOR]

Creating xeric landscapes in lawns and prairies is a significant challenge and practical need in arid urban environments. This study examined the drought resistance of some C4 grass species for constructing urban lawns and prairies. A factorial experiment based on randomized complete block designs with four replications was conducted. Experimental treatments were two irrigation levels (100% and 50% Field Capacity (FC)) and five warm-season grass species (Andropogon gerardii Vitman, Sorghastrum nutans (L.) Nash, Panicum virgatum L., Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torr.). The effects of drought on physiological, morphological, and qualitative characteristics of the grass species were analyzed. Drought conditions induced a decrease in all the measured traits. However, fewer physiological, morphological, and qualitative characteristics were affected by drought stress on Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, compared to the other two species. Overall, warm-season grasses of Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, had greater adaptability to drought stress, making them promising C4 grass species for prairie or lawn landscaping in arid urban environments. Landscape professionals and decision-makers should consider using Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, as these were the most resilient grass species for drought-tolerant prairie landscaping schemes. Sorghastrum nutans and Panicum virgatum may be used as a second priority if a more diverse variety of grasses is required for drought-resilient prairie or lawn landscaping in arid cities.

Abstract Background The decrease in Cunninghamia lanceolata (Lamb.) production on continuously planted soil is an essential problem. In this study, two-year-old seedlings of two cultivars (a normal cultivar, NC, and a super cultivar, SC) were grown in two types of soil (not planted (NP) soil; continuously planted (CP) soil) with three watering regimes, and the interactive effects on plant growth and physiological traits were investigated in a greenhouse experiment. The water contents of the soil in the control (CK) (normal water content), medium water content (MWC) and low water content (LWC) treatments reached 75−80 %, 45−50 % and 20−25 % of the field water capacity, respectively. Results The results indicated that the CP soil had a negative effect on growth and physiological traits and that the LWC treatment caused even more severe and comprehensive negative effects. In both cultivars, the CP soil significantly decreased the height increment (HI), basal diameter increment (DI), dry matter accumulation (DMA), net photosynthetic rate (Pn), total chlorophyll content (TChl), carotenoid content (Caro) and photosynthetic nitrogen use efficiency (PNUE). Compared to the NP soil, the CP soil also decreased the proline and soluble protein contents, nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE) and increased the nitrogen:phosphorus ratio in roots, stems and leaves. The LWC treatment decreased growth and photosynthesis, changed ecological stoichiometry, induced oxidative stress, promoted water use efficiency and damaged chloroplast ultrastructure. Significant increases in ascorbate peroxidase (APX), peroxidase (POD), soluble protein and proline contents were found in the LWC treatment. Compared with the NC, the SC was more tolerant to the CP soil and water stress, as indicated by the higher levels of DMA, Pn, and WUE. After exposure to the CP soil and watering regimes, the decreases in biomass accumulation and gas exchange were more pronounced. Conclusions The combination of drought and CP soil may have detrimental effects on C. lanceolata growth, and low water content enhances the impacts of CP soil stress on C. lanceolata seedlings. The superiority of the SC over the NC is significant in Chinese fir plantation soil. Therefore, continuously planted soil can be utilized to cultivate improved varieties of C. lanceolata and maintain water capacity. This can improve their growth and physiological performance to a certain extent.

Medicinal plants, as important agricultural products, can be considered as the greatest national wealth for any country because of their vital role in promoting national goals for health and also as genetic treasures. Having a diversity of climates, Iran has a great variety of medicinal plants. Detecting the growth status of medicinal plants under drought stress conditions can lead to the cultivation of resistant plants in dry or semidry areas. In the present study, we investigated the morphological and physiological responses of ten ecotypes of the medicinal plant Teucrium polium L. native to southeastern Iran under drought stress. For this purpose, a factorial greenhouse experiment was conducted in a completely randomized design with three replications. In this experiment, moisture treatments of 100, 70, and 40% of field capacity were applied. Analysis of the data showed that the morphological traits under study including stem length and fresh and dry weight of shoots decreased by 5% with increasing drought stress. Drought stress also increased root length, proline content, and phenolic compounds while decreasing chlorophyll a, b, total chlorophyll, and protein contents. The highest resistance to stress was shown by ecotypes growing in Sarcheshmeh and Kuhpayeh regions and the lowest resistance was shown by plants in Shahdad and Anbarabad regions. The results of the study indicated the relative resistance of this plant to drought stress. Therefore, it is a very suitable medicinal plant for cultivation in dry and low water areas of Iran. Among the studied ecotypes, the plants of Sarcheshmeh and Kuhpayeh regions responded 40% better to drought stress conditions and cultivation of these ecotypes in stressed areas can be recommended with more confidence.

For important economic crops such as cucumbers, abiotic and biotic stress conditions have had an adverse effect. This study aimed to observe the effects of water stress and powdery mildew stress on cucumber plants. Biotic stress at two levels, B0 (no powdery mildew stress) and B1 (powdery mildew stress) with three fertigation requirement levels (T1: Full fertigation, T2: Moderate nutrient solution deficit, T3: Severe nutrient solution deficit). Therefore, set up six treatments of B0T1, B1T2, B0T3, B1T1, B1T2, and B1T3. Leaf gas-exchange parameter first decreases and then increases under B1T1, B1T2, and B1T2. The leaf gas exchange parameter was significantly decreased under B0T2 and B0T3. Compared to the control experiment (CK, B0T1: no disease infestation and full irrigation), the plant height of cucumber decreased by 7.55%, 10.62%, 15.28%, 23.27%, and 35.16%, respectively, under B0T2, B0T3, B1T1, B1T2 and B1T3; the stem diameter of cucumber decreased by 9.46%, 15.74%, 5.47%, 13.45%, and 23.72%, respectively, under B0T2, B0T3, B1T1, B1T2, and B1T3; the leaf area of cucumber decreased by 13.76%, 29.96%, 13.43%, 38.21%, and 66.83%, respectively, under B0T2, B0T3, B1T1, B1T2, and B1T3. The root-shoot ratio of cucumber was 3.92%, 3.13%, 3.63%, 3.84%, 4.41%, and 3.82%, respectively, under the B0T1, B0T2, B0T3, B1T1, B1T2, and B1T3. Therefore, this study can provide a basis for the research on greenhouse environmental control and cucumber cultivation management. [ABSTRACT FROM AUTHOR]

This work aimed to study the effects in tomato (Solanum lycopersicum L.) of foliar applications of a novel calcium-based biostimulant (SOB01) using an omics approach involving transcriptomics and physiological profiling. A calcium-chloride fertilizer (SOB02) was used as a product reference standard. Plants were grown under well-watered (WW) and water stress (WS) conditions in a growth chamber. We firstly compared the transcriptome profile of treated and untreated tomato plants using the software RStudio. Totally, 968 and 1,657 differentially expressed genes (DEGs) (adj- p -value < 0.1 and |log2(fold change)| ≥ 1) were identified after SOB01 and SOB02 leaf treatments, respectively. Expression patterns of 9 DEGs involved in nutrient metabolism and osmotic stress tolerance were validated by real-time quantitative reverse transcription PCR (RT-qPCR) analysis. Principal component analysis (PCA) on RT-qPCR results highlighted that the gene expression profiles after SOB01 treatment in different water regimes were clustering together, suggesting that the expression pattern of the analyzed genes in well water and water stress plants was similar in the presence of SOB01 treatment. Physiological analyses demonstrated that the biostimulant application increased the photosynthetic rate and the chlorophyll content under water deficiency compared to the standard fertilizer and led to a higher yield in terms of fruit dry matter and a reduction in the number of cracked fruits. In conclusion, transcriptome and physiological profiling provided comprehensive information on the biostimulant effects highlighting that SOB01 applications improved the ability of the tomato plants to mitigate the negative effects of water stress. [ABSTRACT FROM AUTHOR]

Deficit irrigation is a common approach in water-scarce regions to balance productivity and water use, whereas drought stress still occurs to various extents, leading to reduced physiological performance and a decrease in yield. Therefore, seeking a rapid and reliable method to identify wheat varieties with drought resistance can help reduce yield loss under water deficit. In this study, we compared ten wheat varieties under three deficit irrigation systems (W0, no irrigation during the growing season; W1, irrigation at jointing; W2, irrigation at jointing and anthesis). UAV thermal imagery, plant physiological traits [leaf area index (LAI), SPAD, photosynthesis (Pn), transpiration (Tr), stomatal conductance (Cn)], biomass and yield were acquired at different growth stages. Wheat drought resistance performance was evaluated through using the canopy temperature extracted from UAV thermal imagery (CT-UAV), in combination with hierarchical cluster analysis (HCA). The CT-UAV of W0 and W1 treatments was significantly higher than in the W2 treatment, with the ranges of 24.8–33.3 °C, 24.3–31.6 °C, and 24.1–28.9 °C in W0, W1 and W2, respectively. We found negative correlations between CT-UAV and LAI, SPAD, Pn, Tr, Cn and biomass under the W0 (R2 = 0.41–0.79) and W1 treatments (R2 = 0.22–0.72), but little relevance for W2 treatment. Under the deficit irrigation treatments (W0 and W1), UAV thermal imagery was less effective before the grain-filling stage in evaluating drought resistance. This study demonstrates the potential of ensuring yield and saving irrigation water by identifying suitable wheat varieties for different water-scarce irrigation scenarios.

Background: The decrease in Cunninghamia lanceolata (Lamb.) production on continuously planted soil is an essential problem. In this study, two-year-old seedlings of two cultivars (a normal cultivar, NC, and a super cultivar, SC) were grown in two types of soil (not planted (NP) soil; continuously planted (CP) soil) with three watering regimes, and the interactive effects on plant growth and physiological traits were investigated in a greenhouse experiment. The water contents of the soil in the control (CK) (normal water content), medium water content (MWC) and low water content (LWC) treatments reached 75−80 %, 45−50 % and 20−25 % of the field water capacity, respectively. Results: The results indicated that the CP soil had a negative effect on growth and physiological traits and that the LWC treatment caused even more severe and comprehensive negative effects. In both cultivars, the CP soil significantly decreased the height increment (HI), basal diameter increment (DI), dry matter accumulation (DMA), net photosynthetic rate (Pn), total chlorophyll content (TChl), carotenoid content (Caro) and photosynthetic nitrogen use efficiency (PNUE). Compared to the NP soil, the CP soil also decreased the proline and soluble protein contents, nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE) and increased the nitrogen:phosphorus ratio in roots, stems and leaves. The LWC treatment decreased growth and photosynthesis, changed ecological stoichiometry, induced oxidative stress, promoted water use efficiency and damaged chloroplast ultrastructure. Significant increases in ascorbate peroxidase (APX), peroxidase (POD), soluble protein and proline contents were found in the LWC treatment. Compared with the NC, the SC was more tolerant to the CP soil and water stress, as indicated by the higher levels of DMA, Pn, and WUE. After exposure to the CP soil and watering regimes, the decreases in biomass accumulation and gas exchange were more pronounced. Conclusions: The combination of drought and CP soil may have detrimental effects on C. lanceolata growth, and low water content enhances the impacts of CP soil stress on C. lanceolata seedlings. The superiority of the SC over the NC is significant in Chinese fir plantation soil. Therefore, continuously planted soil can be utilized to cultivate improved varieties of C. lanceolata and maintain water capacity. This can improve their growth and physiological performance to a certain extent. [ABSTRACT FROM AUTHOR]

Nano fertilizers offer benefits in nutrition management through their strong potential to increase nutrient use efficiency. Traditional fertilizers are not only costly for the producer but may be harmful to humans and the environment. Furthermore, nano fertilizers may also be used for enhancing abiotic stress tolerance. This study was performed on the evaluation of nano chelated nitrogen and urea fertilizers on the physiological characteristics of wheat under drought stress conditions. Experiments were carried out in two locations in Fars province, Iran. The experimental design was performed as a split-split plot in RCBD design. The first factor included irrigation treatments (normal and withholding irrigation at the flowering stage), sub factor was nitrogen treatment (0, 37, 74 and 110 k g.ha-1) in the form of Urea fertilizer, and sub-sub factor was nitrogen (0, 14, 27 and 41 kg.ha-1) in the form of nano chelated nitrogen fertilizer. Studied traits were RWC, Ion Leakage, Protein, Phosphorus and Potassium content, Remobilization and photosynthesis rate. According to the analysis of variances, stress, nitrogen (urea) and nano chelated nitrogen had significant effects on all studied traits. Mean comparisons showed that drought stress led to 13% reduction in RWC, 21% Ion Leakage, 26% Protein, 13% Phosphorus and 26% Potassium content, 22% Remobilization and 69% photosynthesis rate compared to normal irrigation. In conclusion Application of 41 kg.ha-1 nano chelated nitrogen fertilizer in comparison with urea led to increase 4% in Rwc, 3% Ion leakage, 52% protein, 26% phosphor, 6% potassium, 6% Remobilization and 21% photosynthesis rate compared to control, respectively.

Nano fertilizers offer benefits in nutrition management through their strong potential to increase nutrient use efficiency. Traditional fertilizers are not only costly for the producer but may be harmful to humans and the environment. Furthermore, nano fertilizers may also be used for enhancing abiotic stress tolerance. This study was performed on the evaluation of nano chelated nitrogen and urea fertilizers on the physiological characteristics of wheat under drought stress conditions. Experiments were carried out in two locations in Fars province, Iran. The experimental design was performed as a split-split plot in RCBD design. The first factor included irrigation treatments (normal and withholding irrigation at the flowering stage), sub factor was nitrogen treatment (0, 37, 74 and 110 k g.ha-1 ) in the form of Urea fertilizer, and sub-sub factor was nitrogen (0, 14, 27 and 41 kg.ha-1 ) in the form of nano chelated nitrogen fertilizer. Studied traits were RWC, Ion Leakage, Protein, Phosphorus and Potassium content, Remobilization and photosynthesis rate. According to the analysis of variances, stress, nitrogen (urea) and nano chelated nitrogen had significant effects on all studied traits. Mean comparisons showed that drought stress led to 13% reduction in RWC, 21% Ion Leakage, 26% Protein, 13% Phosphorus and 26% Potassium content, 22% Remobilization and 69% photosynthesis rate compared to normal irrigation. In conclusion Application of 41 kg.ha-1 nano chelated nitrogen fertilizer in comparison with urea led to increase 4% in Rwc, 3% Ion leakage, 52% protein, 26% phosphor, 6% potassium, 6% Remobilization and 21% photosynthesis rate compared to control, respectively. [ABSTRACT FROM AUTHOR]

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In order to reduce the damage caused by the late-season drought stress of canola, a factorial split-plot experiment was performed based on the randomized complete blocks design with three replications in Karaj, Iran. The treatments were Potassium sulfate in two levels, including application and non-application of potassium sulfate, irrigation at three levels including normal irrigation (control), restricted irrigation from the flowering and pod formation stage, as factorial were in main plots and winter canola cultivars including Opera, L72, KR1, GKH3705, GKH0224 were in subplots. The simple effect of irrigation and potassium sulfate on all of the studied traits and the simple effect of cultivar on all traits except chlorophyll b were significant. The interaction effect of irrigation × cultivar on soluble carbohydrate, stomatal resistance, proline content, chlorophyll a and total chlorophyll content was significant. The interaction effect of irrigation × potassium sulfate on the amount of soluble carbohydrates, stomatal resistance and proline content of leaves was significant. In irrigation interruption from the pod formation stage, the promising line of L72, and in irrigation interruption from the flowering stage, the Neptune cultivar exhibited the most positive effect of potassium application on the studied traits. As a result, the application of potassium sulfate in addition to the L72 and Neptune cultivars is recommended in areas similar to the tested area encountering the late-season drought stress. [ABSTRACT FROM AUTHOR]

Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The objective of this study was to determine the effect of AM inoculation on plant characteristics, lipid peroxidation, solute accumulation, water deficit saturation, photosynthetic activity, total phenol secretion and enzymatic activities including peroxidise (PO) and polyphenol oxidase (PPO) in two bread wheat cultivars (PAN3497 and SST806) under well-watered and drought-stressed conditions in plants grown under greenhouse conditions, to determine whether AM can enhance drought tolerance in wheat. AM inoculation improved morphological and physiological parameters in plants under stress. The leaf number increased by 35% and 5%, tiller number by 25% and 23%, chlorophyll content by 7% and 10%, accumulation of soluble sugars by 33% and 14%, electrolyte leakage by 26% and 32%, PPO by 44% and 47% and PO by 30% and 37% respectively, in PAN3497 and SST806, respectively. However, drought stress decreased proline content by 20% and 24%, oxidative damage to lipids measured as malondialdehyde by 34% and 60%, and total phenol content by 55% and 40% respectively, in AM treated plants of PAN3497 and SST806. PAN3497 was generally more drought-sensitive than SST806. This study showed that AM can contribute to protect plants against drought stress by alleviating water deficit induced oxidative stress.

In this research, considering the importance of drought and canola, an experiment was done as factorial in a Randomized Complete Block Design using ten spring canola cultivars with hydroponic method in seedling stage and with induced of drought stress by PEG6000. Two weeks after of the stress induction and at the end of the rossete stage, samples were taken. The results showed that the value of morphological and physiological traits was declined under drought stress. Also the studied cultivars were varied in response to drought stress and in general, the most tolerant and sensitive cultivars for studied traits were SW5001 and Sarigol cultivars, respectively that to graduate studies on these two cultivars proteome analysis was performed. To study the pattern of protein, extraction of protein from leaf tissue was performed and the first dimension electrophoresis using IPG strips and second dimension electrophoresis was performed by SDS-PAGE technique and after the gels staining with commassie blue, gels imaging with scanner and protein analysis with PDQuest software was done. Finally a total of 25 protein spots between control plants and under drought stress for both cultivars were detected that of these, 15 protein spots were common between two cultivars and six unique protein spots for tolerant cultivar and four unique protein spots for susceptible cultivar. After detection these proteins with mass spectrometry, overall, the most common protein groups between two cultivars were involved proteins in photo-reaction of photosynthesis, Calvin cycle and detoxifying enzymes. In total, the most important cause of the sensitivity and tolerance of canola cultivars different expression and unique expression of proteins into cultivars and finally effects of them on other were obtained.

This study was carried out to determine the changes in chlorophyll and ion contents, lipid peroxidation level, and antioxidative enzyme activities of 4 eggplant genotypes (Mardin Kızıltepe (MK), Burdur Merkez (BM), Artvin Hopa (AH), and Kemer (K)) with different salt tolerance levels under drought stress. Experiments were conducted in a greenhouse with controlled climatic conditions. When the plants reached the 3-4 leaves stage, 3 different treatments were applied to create the drought levels. The first condition in the study was obtained through control application treatment (D0), which was depletion of 40% of the available water holding capacity. The second application (D1) was depletion of 90% of the available water holding capacity. The third application (D2) was no applied irrigation water. Plants were analyzed with regards to chlorophyll and ion contents, lipid peroxidation levels, and antioxidative enzyme activities. Significant differences were observed among interactions of genotypes and levels of drought stress in chlorophyll and ion (K+, Ca2+, Zn2+, Mn2+, and Fe2+) contents, lipid peroxidation levels, and activities of antioxidant enzymes (superoxide dismutase-SOD, catalase-CAT, glutathione reductase-GR, and ascorbate peroxidase-APX). The chlorophyll and ion contents of eggplant genotypes under drought stress decreased. However, different levels of lipid peroxidation and antioxidative enzyme activities were observed. The situation changed depending on genotypes. Lipid peroxidation levels increased under drought stress, especially in salt-sensitive genotypes (AH and K). On the other hand, the activities of antioxidative enzymes in the salt tolerant MK and BM genotypes significantly increased. With regard to the investigated traits, salt-tolerant genotypes were also found to be quite tolerant against drought stress. [ABSTRACT FROM AUTHOR]

Assessment of genotypic variability in germplasm under different water stress conditions is one of the most challenging objectives in crop breeding programs. We evaluated responses of 130 indigenous rice (Oryza sativa L.) landraces that originated from various regions of Jeypore tract of Odisha, India, to drought stress for two years. Drought-tolerant (N22) and drought-susceptible (IR64) checks were also included in the experiment. Drought stress was induced by polyethylene glycol (PEG) 6000. The following traits were measured: seed germination, shoot and root length, fresh and dry weight, relative water content (RWC), membrane stability index (MSI), chlorophyll concentration (SPAD), and osmolyte accumulation. In principal component analysis (PCA), the first three principal components (PCs) captured 62.46% of the total variation; significant differences were detected among genotypes with respect to the studied parameters. The genetic advance (5% selection intensity) as the percentage of mean (GAM) ranged from 10.71% for RWC to 73.60% for root length. GAM was relatively high for germination percentage (42.85%), shoot length (SL) (55.14%), root length (RL) (73.60%), chlorophyll index (54.24%), proline content (56.73%), and vigor index (VI) (66.98%). Hence, these traits should be given top priority during selection for rice improvement programs using the studied landraces. Six landraces (Pandakagura, Machhakanta, Haladichudi, Mugudi, Kalajeera, and Dangarbayagundar), being more drought tolerant than N22, should be useful in rice breeding programs aimed at improving drought tolerance. [ABSTRACT FROM AUTHOR]

BACKGROUND: The strawberry is one of the most important small fruits; it is widely cultivated in the world and is sometimes subjected to drought stress. Investigating the effects of drought stress on cultivar related plant physiology is necessary to broaden the knowledge of resistance mechanisms to drought. OBJECTIVE: The present study was conducted to investigate the morpho-physiological characteristics of drought tolerance and the relationships between these and strawberry fruit yield under short- and long-term drought stress conditions. METHODS: The effect of two strawberry cultivars, Queen Eliza and Parus, was examined under four moisture regimes. A short-term stress for one month and a long-term stress for four months were undertaken in greenhouse condition. RESULTS: The analysis of variance indicated significant differences between the cultivars for carotenoid content, relative water content, relative water loss, stomatal conductance and quantum yield of photosystem II under short-term stress and stomatal conductance, carotenoid content and membrane stability under long-term stress. Correlation analysis revealed that yield correlated positively with relative water content and quantum yield of photosystem II (Fv/Fm), under short- term and long- term stress. Using factor analysis, totally four factors were identified that accounted for 82.14% of the total variance. The factors were in decreasing order of influence yield components, photosynthesis, physiological characteristics and chlorophyll. CONCLUSIONS: Generally, 'Parus' was superior to 'Queen Eliza' in terms of measured traits under short and long-term stress conditions. It seems that measuring physiological traits is a convenient, simple and fast tool for screening genotypes for their drought tolerance. [ABSTRACT FROM AUTHOR]

Walnut has a high economic value because of the good quality of wood and fruits. So this species has been harvested since many years ago till today and has been introduced as a protected species. The performance of Juglans regia increases in wet years, but reduces in dry years, hence paying attention to physiological and morphological parameters in order to identify the genomic regions related to drought resistant is important for breeding programs in walnut. In this study, genetic diversity by SSR markers has been evaluated. Also, the association of used primers with physiological and morphological traits were analyzed before and after drought stress. 10 SSR primer pairs generated 53 alleles in 62 walnut seedlings. All locies showed significant difference (p≤0.01) from the Hardy-Weinberg. Dendrogram of the Neighbour-Joining method showed that 62 walnut seedlings divided to four main groups. Analyses of population structure by Structure 2.3.1 software identified two sub populations (k=2). Based on association mapping analysis, by using MLM (mixed liner model) method, transpiration, conductance and photosynthesis have been controlled by WGA9 and WGA69 locies in normal condition. In stress condition WGA1 loci showed relationship with CO2 concentration that was covered %75 of variations of this trait. The results of this study can be used in breeding programs of Juglans regia to identify drought resistant varieties.

Abstract: Drought stress is presently a major productivity limiting factor in wheat. This study developed five wheat lines with inbuilt tolerance to drought stress using marker‐assisted backcross breeding (MABB) approach employing three linked quantitative trait loci (QTLs) in an initial population of 516 BC1F1 plants. The high‐yielding wheat cultivar ‘HD2733’ grown over last few years extensively in the eastern plains of India is largely sensitive to drought and is used as the recurrent parent. ‘HI1500’ released for water‐limiting conditions and carrying drought‐tolerant QTLs was used as donor parent. MABB lines were advanced using foreground and background selection, coupled with stringent phenotyping. We identified 29 lines that were homozygous for targeted QTLs in different combinations with background recovery range of 89.2%–95.4%. Further evaluation of selected lines for physiological traits and distinctness, uniformity and stability (DUS) characters under rainfed condition identified five potential varieties for national varietal evaluation programme in the zone. The report is first of its kind in implementing known QTLs for the development of drought‐tolerant wheat lines through MABB approach. [ABSTRACT FROM AUTHOR]

To locate the loci controlling physiological traits of barley in seedling stage, an experiment was conducted under drought stress and normal irrigation in greenhouse as a completely randomized design with two replications in Iran in 2016. For this purpose, the populations of Cebad Capa (C. Capa) × Susptrit (S) and Vada (V) × Susptrit (S) with their parents were separately cultivated under drought stress condition and normal irrigation. 112 and 89 Recombinant Inbred Lines respectively resulted from V × S and C. Capa × S were used. Susptrit was used as drought tolerant cultivar and Vada and Cebada Capa were selected as sensitive cultivars. In this experiment Chlorophyll content (CC), relative water content (RWC), shoot dry weight (SDW) and leaf temperature (LT) were measured. For each population and environment, QTL (Quantitative Trait Loci) analysis was done based on composite interval mapping on the lines separately. The results showed the effect of genotype was significant for all traits. 43 locations covering QTLs were identified in both populations and both environments. 15 QTLs were located for C. Capa × S under drought stress. The identified QTLs under drought stress were identified as three QTLs for RWC on chromosomes 4 and 5, six QTLs for chlorophyll content as two QTLs for CC-30%FC and two QTLs for CC-50%FC on chromosomes 3 and 7, two QTLs for CC-20%FC on chromosomes 4 and 7, three QTLs for SDW on chromosomes 1 and 6, and three QTLs for LT on chromosomes 4, 6, and 7. In contrast, two QTLs on chromosomes 3 and 6 were detected under normal irrigation for SDW. In addition, 13 QTLs were located for V×S under drought stress. 10 QTLs were observed for chlorophyll content as three QTLs for CC-50%FC on chromosomes 3 and 7, three QTLs for CC-30%FC on chromosomes 1, 2, and 5, four QTLs for CC-20%FC on chromosomes 2, 3 and 6. For RWC, there were identified two QTLs on chromosomes 4 and 6, while a QTL was recorded for SDW on chromosomes 6. Our study showed stable QTLs within and between populations, which it can be used in selection process by markers. [ABSTRACT FROM AUTHOR]

Development of wheat varieties with low moisture requirements and their ability to withstand moisture stress may cope-up well with the on-coming peril of drought conditions. Ten wheat genotypes including two new strains, PBGST-3, Hero, Bhittai, Marvi, Inqlab, Sarsabz, Abadgar, Kiran, Khirman and PBGST-4 were sown in split plot design with factorial arrangement in four replications at Experimental Field, Department of Plant Breeding & Genetics, Sindh Agricutlure University, Pakistan during 2012-13. The results revealed that water stress caused significant reductions in all morpho-physiological traits. The genotypes differed significantly for all the yield and physiological traits. The interaction of treatments × genotypes were also significant for all the traits except plant height, productive tillers/plant, grains/spike and harvest index, were non-significant which indicated that cultivars responded variably over the stress treatments suggesting that breeders can select the promising genotypes for both stress and non-stress environments. Among the genotypes evaluated Bhittai, Kiran-95, PBGST-3 and Sarsabz showed good performance as minimum reductions occurred under terminal stress conditions for all the traits studied. Hence, above mentioned genotypes were considered as drought tolerant group. The high positive correlations of physiological traits like chlorophyll content and relative water content with almost all yield traits indicated that these physiological traits could serve as reliable criteria for breeding drought tolerance in wheat. The negative correlations of electrolyte leakage with several important yield traits indicated that though this physiological trait has adverse effect on yield attributes, yet it could reliably be used to distinguish between drought tolerant and susceptible wheat genotypes. [ABSTRACT FROM AUTHOR]

[Objectives] To study changes in SOD, POD, CAT, MAD and Pro content of S. miltiorrhiza Bunge seedlings and the effects of brassinolide (BR) on drought resistance of S. miltiorrhiza Bunge. [Methods] 6 varieties of S. miltiorrhiza Bunge produced in Zhongjiang County of Sichuan Province were used as research object, and the method of PEG-6000 simulated drought stress was applied. [Results] 20% PEG stress 9 d was used as the optimal simulation condition of drought stress. Under the same degree of drought stress, tissue-cultured big leaf S. miltiorrhiza Bunge showed the highest SOD and POD activity, tissue-cultured small leaf S. miltiorrhiza Bunge showed highest CAT activity, long-stalked big leaf S. miltiorrhiza Bunge had lower MDA content than other varieties, and Zhongjiang wild S. miltiorrhiza Bunge had the highest Pro content. [Conclusions] BR can indirectly improve drought resistance ability of S. miltiorrhoa Bunge, and 0.1 mg/L BR has the best action effect. [ABSTRACT FROM AUTHOR]