Drought Stress Research Articles

Exogenous Glycinebetaine Regulates the Contrasting Responses in Leaf Physiochemical Attributes and Growth of Maize under Drought and Flooding Stresses.

Flooding and drought are the two most devastating natural hazards limiting maize production. Exogenous glycinebetaine (GB), an osmotic adjustment agent, has been extensively used but there is limited research on its role in mitigating the negative effects of different abiotic stresses. This study aims to identify the different roles of GB in regulating the diverse defense regulation of maize against drought and flooding. Hybrids of Yindieyu 9 and Heyu 397 grown in pots in a ventilated greenhouse were subjected to flooding (2-3 cm standing layer) and drought (40-45% field capacity) at the three-leaf stage for 8 d. The effects of different concentrations of foliar GB (0, 0.5, 1.0, 5.0, and 10.0 mM) on the physiochemical attributes and growth of maize were tested. Greater drought than flooding tolerance in both varieties to combat oxidative stress was associated with higher antioxidant activities and proline content. While flooding decreased superoxide dismutase and guaiacol peroxidase (POD) activities and proline content compared to normal water, they all declined with stress duration, leading to a larger reactive oxygen species compared to drought. It was POD under drought stress and ascorbate peroxidase under flooding stress that played crucial roles in tolerating water stress. Foliar GB further enhanced antioxidant ability and contributed more effects to POD to eliminate more hydrogen peroxide than the superoxide anion, promoting growth, especially for leaves under water stress. Furthermore, exogenous GB made a greater increment in Heyu 397 than Yindieyu 9, as well as flooding compared to drought. Overall, a GB concentration of 5.0 mM, with a non-toxic effect on well-watered maize, was determined to be optimal for the effective mitigation of water-stress damage to the physiochemical characteristics and growth of maize.

Rapeseed PP2C37 Interacts with PYR/PYL Abscisic Acid Receptors and Negatively Regulates Drought Tolerance.

Global water deficit is a severe abiotic stress threatening the yielding and quality of crops. Abscisic acid (ABA) is a phytohormone that mediates drought tolerance. Protein kinases and phosphatases function as molecular switches in eukaryotes. Protein phosphatases type 2C (PP2Cs) are a major family that play essential roles in ABA signaling and stress responses. However, the role and underlying mechanism of PP2C in rapeseed (Brassica napus L.) mediating drought response has not been reported yet. Here, we characterized a PP2C family member, BnaPP2C37, and its expression level was highly induced by ABA and dehydration treatments. It negatively regulates drought tolerance in rapeseed. We further identified that BnaPP2C37 interacted with multiple PYR/PYL receptors and a drought regulator BnaCPK5 (calcium-dependent protein kinase 5) through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Specifically, BnaPYL1 and BnaPYL9 repress BnaPP2C37 phosphatase activity. Moreover, the pull-down assay and phosphatase assays show BnaPP2C37 interacts with BnaCPK5 to dephosphorylate BnaCPK5 and its downstream BnaABF3. Furthermore, a dual-luciferase assay revealed BnaPP2C37 transcript level was enhanced by BnaABF3 and BnaABF4, forming a negative feedback regulation to ABA response. In summary, we identified that BnaPP2C37 functions negatively in drought tolerance of rapeseed, and its phosphatase activity is repressed by BnaPYL1/9 whereas its transcriptional level is upregulated by BnaABF3/4.

Rain and potential evapotranspiration are the main drivers of yield for wheat and barley in southern Australia: insights from 12 years of National Variety Trials

Context Water is widely assumed to be the factor most limiting the growth of annual crops in rainfed environments, but this is rarely tested at sub-continental scale. Aims Our study aimed to determine the key environmental and management variables influencing the yield of wheat and barley in the grain-production regions of southern Australia, using data from National Variety Trials. Methods We used generalised additive models to determine the importance of climatic and management variables on wheat and barley grain yield. We determined the effects of the best one, two or three variables and their interactions. Key results The aridity index, defined as the ratio of cumulative rainfall to potential evapotranspiration, was the single strongest determinant of grain yield for both crops. Model performance was further improved by separating the aridity index into pre-seasonal and seasonal components. Interestingly, other variables that might be expected to influence yield, such as nitrogen fertilisation and extreme temperatures, had relatively minor effects. A comparison between data collected over two 6-year periods showed that there had been yield gains and increased water-use efficiency with time, especially in wetter environments. Conclusions Our findings illustrate the importance of water availability for grain production in this region and suggest opportunities for benchmarking and yield prediction through use of readily available climate data. Implications Our study reinforces the importance of factors such as water-use efficiency and drought tolerance as goals for cultivar development and agronomic research in wheat and barley. It also highlights the potential of National Variety Trial data as a resource for understanding grain production systems and climate resilience. Further work could explore the value of additional variables and improved weather data.

In silico analysis identified bZIP transcription factors genes responsive to abiotic stress in Alfalfa (Medicago sativa L.)

BackgroundAlfalfa (Medicago sativa L.) is the most cultivated forage legume around the world. Under a variety of growing conditions, forage yield in alfalfa is stymied by biotic and abiotic stresses including heat, salt, drought, and disease. Given the sessile nature of plants, they use strategies including, but not limited to, differential gene expression to respond to environmental cues. Transcription factors control the expression of genes that contribute to or enable tolerance and survival during periods of stress. Basic-leucine zipper (bZIP) transcription factors have been demonstrated to play a critical role in regulating plant growth and development as well as mediate the responses to abiotic stress in several species, including Arabidopsis thaliana, Oryza sativa, Lotus japonicus and Medicago truncatula. However, there is little information about bZIP transcription factors in cultivated alfalfa.ResultIn the present study, 237 bZIP genes were identified in alfalfa from publicly available sequencing data. Multiple sequence alignments showed the presence of intact bZIP motifs in the identified sequences. Based on previous phylogenetic analyses in A. thaliana, alfalfa bZIPs were similarly divided and fell into 10 groups. The physico-chemical properties, motif analysis and phylogenetic study of the alfalfa bZIPs revealed high specificity within groups. The differential expression of alfalfa bZIPs in a suite of tissues indicates that bZIP genes are specifically expressed at different developmental stages in alfalfa. Similarly, expression analysis in response to ABA, cold, drought and salt stresses, indicates that a subset of bZIP genes are also differentially expressed and likely play a role in abiotic stress signaling and/or tolerance. RT-qPCR analysis on selected genes further verified these differential expression patterns.ConclusionsTaken together, this work provides a framework for the future study of bZIPs in alfalfa and presents candidate bZIPs involved in stress-response signaling.

RIP5 Interacts with REL1 and Negatively Regulates Drought Tolerance in Rice.

Improving the drought resistance of rice is of great significance for expanding the planting area and improving the stable yield of rice. In our previous work, we found that ROLLED AND ERECT LEAF1 (REL1) protein promoted enhanced tolerance to drought stress by eliminating reactive oxygen species (ROS) levels and triggering the abscisic acid (ABA) response. However, the mechanism through which REL1 regulates drought tolerance by removing ROS is unclear. In this study, we identified REL1 interacting protein 5 (RIP5) and found that it directly combines with REL1 in the chloroplast. We found that RIP5 was strongly expressed in ZH11 under drought-stress conditions, and that the rip5-ko mutants significantly improved the tolerance of rice plants to drought, whereas overexpression of RIP5 resulted in greater susceptibility to drought. Further investigation suggested that RIP5 negatively regulated drought tolerance in rice by decreasing the content of ascorbic acid (AsA), thereby reducing ROS clearance. RNA sequencing showed that the knockout of RIP5 caused differential gene expression that is chiefly associated with ascorbate and aldarate metabolism. Furthermore, multiple experimental results suggest that REL1 is involved in regulating drought tolerance by inhibiting RIP5. Collectively, our findings reveal the importance of the inhibition of RIP5 by REL1 in affecting the rice's response to drought stress. This work not only explains the drought tolerance mechanism of rice, but will also help to improve the drought tolerance of rice.

Drought response revealed by chromatin organization variation and transcriptional regulation in cotton

BackgroundCotton is a major world cash crop and an important source of natural fiber, oil, and protein. Drought stress is becoming a restrictive factor affecting cotton production. To facilitate the development of drought-tolerant cotton varieties, it is necessary to study the molecular mechanism of drought stress response by exploring key drought-resistant genes and related regulatory factors.ResultsIn this study, two cotton varieties, ZY007 (drought-sensitive) and ZY168 (drought-tolerant), showing obvious phenotypic differences under drought stress, were selected. A total of 25,898 drought-induced genes were identified, exhibiting significant enrichment in pathways related to plant stress responses. Under drought induction, At subgenome expression bias was observed at the whole-genome level, which may be due to stronger inhibition of Dt subgenome expression. A gene co-expression module that was significantly associated with drought resistance was identified. About 90% of topologically associating domain (TAD) boundaries were stable, and 6613 TAD variation events were identified between the two varieties under drought. We identified 92 genes in ZY007 and 98 in ZY168 related to chromatin 3D structural variation and induced by drought stress. These genes are closely linked to the cotton response to drought stress through canonical hormone-responsive pathways, modulation of kinase and phosphatase activities, facilitation of calcium ion transport, and other related molecular mechanisms.ConclusionsThese results lay a foundation for elucidating the molecular mechanism of the cotton drought response and provide important regulatory locus and gene resources for the future molecular breeding of drought-resistant cotton varieties.

Mitigation of drought stress effects on alfalfa (Medicago sativa L.) callus through CaO nanoparticles and graphene oxide in tissue culture conditions

Drought stress poses a significant threat to fertile soils worldwide, triggering profound physiological, biochemical, and molecular changes in plants that adversely impact agricultural productivity. This study explores the potential of nanotechnology, specifically Calcium Oxide Nanoparticles (CaO NPs) and Graphene Oxide (GO), to ameliorate the negative effects of drought stress on two distinct alfalfa ecotypes. Seeds from Erzurum and Konya regions were regenerated in the Murashige and Skoog (MS) medium, and ensuing callus formation was induced through 1 mg L−1 2,4-D and 1 mg L−1 kinetin MS medium. The callus samples underwent a one-month treatment with varying concentrations of mannitol (50 and 100 mM), CaO NPs, and GO (0.5 and 1.5 ppm). Results revealed a decrease in dry/wet weight with increasing mannitol concentration, contrasting with an increase in weight under CaO NPs and GO treatment. Proline, DNSA, MDA, and H2O2 exhibited proportional increases under drought stress, while CaO NPs and GO treatments mitigated these effects. Physiological and biochemical analyses identified optimal conditions for Erzurum as 50 mM mannitol/2 CaO NPs/0.5 ppm GO, and for Konya as 50 mM mannitol/0.5 ppm GO. Gene expression analysis indicated up-regulation of mtr-miR159 and mtr-miR393 with heightened drought stress, with down-regulation observed in CaO NPs and GO treatments. Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) confirmed Ca2+ accumulation in alfalfa tissues. In conclusion, CaO NPs and GO treatments exhibited a significant reduction in the adverse effects of drought stress on alfalfa callus under tissue culture conditions. This research sheds light on the potential of nanotechnological interventions to alleviate the impact of environmental stressors on crop plants, opening avenues for sustainable agriculture in the face of changing climatic conditions. Further investigations are warranted to elucidate the underlying mechanisms and scalability of these findings for field applications.

Identification and Expression Profile of NCED Genes in Arachis hypogaea L. during Drought Stress

Peanut (Arachis hypogaea L.) is an important crop that provides essential proteins and oils for human and animal consumption. 9-cis-epoxycarotenoid dioxygenase (NCED) have been found can play a vital role in abscisic acid (ABA) biosynthesis and may be a response to drought stress. Until now, in Arachis hypogaea, no information about the NCED gene family has been reported and the importance of NCED-related drought tolerance is unclear. In this study, eight NCED genes in Arachis hypogaea, referred to as AhNCEDs, are distributed across eight chromosomes, with duplication events in AhNCED1 and AhNCED2, AhNCED3 and AhNCED4, and AhNCED6 and AhNCED7. Comparative analysis revealed that NCED genes are highly conserved among plant species, including Pisum sativum, Phaseolus vulgaris, Glycine max, Arabidopsis thaliana, Gossypium hirsutum, and Oryza sativa. Further promoter analysis showed AhNCEDs have ABA-related and drought-inducible elements. The phenotyping of Arachis hypogaea cultivars NH5 and FH18 demonstrated that NH5 is drought-tolerant and FH18 is drought-sensitive. Transcriptome expression analysis revealed the differential regulation of AhNCEDs expression in both NH5 and FH18 cultivars under drought stress. Furthermore, compared to the Arachis hypogaea cultivar FH18, the NH5 exhibited a significant upregulation of AhNCED1/2 expression under drought. To sum up, this study provides an insight into the drought-related AhNCED genes, screened out the potential candidates to regulate drought tolerance and ABA biosynthesis in Arachis hypogaea.

Cryptic Resilience: Decoding Molecular Networks in Pearl Millet for Enhanced Heat Stress

Pearl millet (<em>Pennisetum glaucum</em>), a vital cereal crop renowned for its drought tolerance, is a cornerstone for smallholder farmers in arid and semi-arid regions, ranking as the fifth most significant cereal globally. Despite its resilience, the molecular mechanisms underlying its tolerance to heat stress remained elusive. To address this knowledge gap, we subjected ten-day-old pearl millet seedlings to an unprecedented temperature of 50°C for 60 seconds. Subsequent next-generation RNA sequencing aimed to unravel differential gene expression in heat-stressed seedlings compared to control conditions. Our analysis revealed a remarkable 29.8% differential expression in the genome sequence in response to heat stress. Heat-stressed pearl millet leaves exhibited differential expression in 11,483 genes, with fold changes ranging from 2 to 18.6 compared to the control group. Of these, 3,612 genes displayed upregulation, while 7,871 genes exhibited downregulation. These genes play roles in diverse biological processes involving crucial enzymes such as aminoacyl-tRNA synthetases, ligases, methyltransferases, oxidoreductases, and DNA-directed RNA polymerases. The Photosystem II Type I Chlorophyll-a/b-binding protein and heat shock proteins displayed the most significant fold changes in heat-stressed leaves. Moreover, various transcription factor families, including bHLH, ERF, NAC, WRKY, MYB-related, C2H2, bZIP, MYB, FAR1, and B3, vital in controlling pearl millet's response to heat stress, were linked to over 100 differentially expressed genes. The dataset generated through this research, shedding light on the molecular processes enabling pearl millet to withstand heat, holds immense value given the crop's role in food security and resilience to extreme weather. In the context of climate change and global warming, this knowledge lays the foundation for further studies on metabolic engineering and selecting crops resilient to high temperatures. Our transcriptomics approach provides comprehensive gene expression profiles of heat-stressed plants. It elucidates pearl millet's response to heat stress, offering a crucial resource for future investigations into crop adaptation strategies.

International Biological Flora: Ceratonia siliqua

Abstract This account presents information on all aspects of the biology of Ceratonia siliqua L. (Carob) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the International Biological Flora: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Ceratonia siliqua is a lowland evergreen shrub or tree, native around the Mediterranean basin and widely cultivated in areas with a warm temperate and subtropical climate, with more than 100 named cultivars. Carob grows on a wide range of soils including nutrient‐poor and strongly calcareous, dry soils. Carob is dioecious or rarely hermaphrodite although females dominate in cultivation due to their fruit. Pollination is primarily by insects and the relatively large seeds are spread mainly by ingestion of fruits by mammals. Seed dormancy is imposed by a hard seed coat and seeds germinate readily after natural or artificial scarification. Drought tolerance is very high, acting as a drought avoiding water spender. Carob is also very tolerant of saline conditions and tolerant of fire and can act to restrict wildfire spread by generating fuel discontinuity. It shows high post‐fire regrowth. Old individuals house a diversity of associated fauna and are comparatively unaffected by serious pests and diseases. Carob has a long cultural history around the Mediterranean as a food source for humans and domesticated animals, in herbal and modern medicine and, more recently, for the carob bean gum used in a variety of domestic products and foods. Commercial production of fruits has declined over past decades but the low cultural care needed in growing orchards, potential new markets for fruit and seeds, and growing use of the tree to prevent soil erosion and sequester carbon gives carob a brighter future.

Integrated monitoring and modeling to disentangle the complex spatio-temporal dynamics of urbanized streams under drought stress

We have a poor understanding of how urban drainage and other engineered components interact with more natural hydrological processes in green and blue spaces to generate stream flow. This limits the scientific evidence base for predicting and mitigating the effects of future development of the built environment and climate change on urban water resources and their ecosystem services. Here, we synthesize > 20 years of environmental monitoring data to better understand the hydrological function of the 109-km2 Wuhle catchment, an important tributary of the river Spree in Berlin, Germany. More than half (56%) of the catchment is urbanized, leading to substantial flow path alterations. Young water from storm runoff and rapid subsurface flow provided around 20% of stream flow. However, most of it was generated by older groundwater (several years old), mainly recharged through the rural headwaters and non-urban green spaces. Recent drought years since 2018 showed that this base flow component has reduced in response to decreased recharge, causing deterioration in water quality and sections of the stream network to dry out. Attempts to integrate the understanding of engineered and natural processes in a traditional rainfall-runoff model were only partly successful due to uncertainties over the catchment area, effects of sustainable urban drainage, adjacent groundwater pumping, and limited conceptualization of groundwater storage dynamics. The study highlights the need for more extensive and coordinated monitoring and data collection in complex urban catchments and the use of these data in more advanced models of urban hydrology to enhance management.

Sunflower germplasms’ response to different water and salinity stress levels in greenhouse and field conditions under subsurface drip irrigation

AbstractSunflower (Helianthus annuus L.) is moderately tolerant to salt and water stress, but its production can still be significantly and adversely affected by increases in these stressors as a result of the negative impacts of climate change on agricultural soil and crop productivity. The morphological and productivity (dry head weight, dry root weight, dry shoot weight, head diameter, whole seed weight, crude protein content, crude oil content, palmitic acid, stearic acid, oleic acid, linoleic acid, eicosanoic acid, 11‐eicosenoic acid, homo‐gamma‐linolenic w6 acid, lignoceric acid and plant height) responses of modern sunflower germplasms to different levels of salt and drought stress under greenhouse and field conditions were investigated and analysed. Six germplasms were evaluated under three salt concentrations (0, 150 and 250 mM), and two germplasms were evaluated for drought response under three irrigation levels. Significant differences in the response of sunflower germplasms to water and salinity were detected. The same germplasms exhibited significant differences in response to water and salinity between the treatments, which also varied significantly between the germplasms for the same treatment. The irrigation level significantly influenced the amount of oil but not the crude protein or fatty acid composition. The results and information of this research can aid in selecting and improving sunflower productivity under adverse (i.e. saline and drought) conditions.

Botanical Gardens in the U. S. S. R.

In the system of Scientific Botanical Gardens of the Soviet Union, there are 91 Gardens located in different climatic zones. These Gardens are important centres of research for scientific studies of plant introduction, acclimatisation, drought and frost resistance and other problems and are provided with well equipped laboratories. The Gardens are also recognised post-graduate training centres. The impressions gathered by the author during a recent visit to some of these well known Gardens of the Soviet Union are briefly recorded in this paper.

Insights into the Drought Stress Tolerance Mechanisms of Sesame: The Queen of Oilseeds

Insights into the Drought Stress Tolerance Mechanisms of Sesame: The Queen of Oilseeds

Hydrogen Sulfide Increases Drought Tolerance by Modulating Carbon and Nitrogen Metabolism in Foxtail Millet Seedlings

Hydrogen sulfide (H2S), a novel gas signaling molecule, has been shown to enhance plant resistance to various abiotic stresses. Here, we investigated the effect of sodium hydrosulfide (NaHS, a H2S donor) on the growth, photosynthetic parameters, and enzyme activities related to carbon and nitrogen metabolism, as well as the levels of carbohydrates and nitrogen metabolites in foxtail millet seedlings subjected to drought stress conditions in pots. The findings revealed that drought stress led to a significant 41.2% decline in the total dry weight (DW) after 12 days of treatment, whereas plants treated with NaHS showed a lesser reduction of 18.7% in total DW. Under drought stress, exogenous NaHS was found to enhance carbon metabolism in foxtail millet seedlings by significantly enhancing photosynthetic capacity, starch, and sucrose content. Additionally, exogenous NaHS was observed to improve nitrogen metabolism by substantially increasing soluble protein content, nitrogen assimilate activity, and synthesis of nitrogen-containing compounds in foxtail millet seedlings. In summary, the exogenous application of NaHS stimulated seedling growth and enhanced drought resistance in foxtail millet by modulating carbon and nitrogen metabolism processes affected by drought stress.

Genetic control of root architectural traits under drought stress in spring barley (Hordeum vulgare L.).

Root architectural traits play pivotal roles in plant adaptation to drought stress, and hence they are considered promising targets in breeding programs. Here, we phenotyped eight root architecture traits in response to well-watered and drought stress conditions in 200 spring barley (Hordeum vulgare L.) inbred lines over two consecutive field seasons. Root architecture traits were less developed under drought in both seasons when compared with control treatments. Genetic variation in root architectural traits was dissected employing a genome-wide association study (GWAS) coupled with linkage disequilibrium mapping. GWAS uncovered a total of 186 significant single nucleotide polymorphism-trait associations for eight root traits under control, drought, and drought-related indices. Of these, a few loci for root traits were detected on chromosomes 3 and 5, which co-located with QTL identified in previous studies. Interestingly, 13 loci showed simultaneou associations with multiple root traits under drought and drought-related indices. These loci harbored candidate genes, which included a wide range of drought-responsive components such as transcription factors, binding proteins, protein kinases, nutrient and ion transporters, and stress signaling factors. For instance, two candidate genes, HORVU7Hr3G0713160 and HORVU6H r3G0626550, are orthologous to AtACX3 and AtVAMPs, which have reported functions in root length-mediated drought tolerance and as a key protein in abiotic stress tolerance, respectively. Interestingly, one of these loci underlying a high-confidence candidate gene NEW ENHANCER OF ROOT DWARFISM1 (NERD1) showed involvement with root development. An allelic variation of this locus in non-coding region was significantly associated with increased root length under drought. Collectively, these results offer promising multi-trait affecting loci and candidate genes underlying root phenotypic responses to drought stress, which may provide valuable resources for genetic improvement of drought tolerance in barley.

Safflower CtFLS1-Induced Drought Tolerance by Stimulating the Accumulation of Flavonols and Anthocyanins in Arabidopsis thaliana.

Flavonol synthase gene (FLS) is a member of the 2-oxoglutarate-dependent dioxygenase (2-ODD) superfamily and plays an important role in plant flavonoids biosynthetic pathways. Safflower (Carthamus tinctorius L.), a key source of traditional Chinese medicine, is widely cultivated in China. Although the flavonoid biosynthetic pathway has been studied in several model species, it still remains to be explored in safflower. In this study, we aimed to elucidate the role of CtFLS1 gene in flavonoid biosynthesis and drought stress responses. The bioinformatics analysis on the CtFLS1 gene showed that it contains two FLS-specific motifs (PxxxIRxxxEQP and SxxTxLVP), suggesting its independent evolution. Further, the expression level of CtFLS1 in safflower showed a positive correlation with the accumulation level of total flavonoid content in four different flowering stages. In addition, CtFLS1-overexpression (OE) Arabidopsis plants significantly induced the expression levels of key genes involved in flavonol pathway. On the contrary, the expression of anthocyanin pathway-related genes and MYB transcription factors showed down-regulation. Furthermore, CtFLS1-OE plants promoted seed germination, as well as resistance to osmotic pressure and drought, and reduced sensitivity to ABA compared to mutant and wild-type plants. Moreover, CtFLS1 and CtANS1 were both subcellularly located at the cell membrane and nucleus; the yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assay showed that they interacted with each other at the cell membrane. Altogether, these findings suggest the positive role of CtFLS1 in alleviating drought stress by stimulating flavonols and anthocyanin accumulation in safflower.

An expanded cysteine-rich receptor-like kinase gene cluster functionally differentiates in drought, cold, heat, and pathogen stress responses in rice.

An expanded cysteine-rich receptor-like kinase gene cluster functionally differentiates in drought, cold, heat, and pathogen stress responses in rice.

Individual and interactive effects of amino acid and paracetamol on growth, physiological and biochemical aspects of Brassica napus L. under drought conditions

Drought stress poses a significant threat to Brassica napus (L.), impacting its growth, yield, and profitability. This study investigates the effects of foliar application of individual and interactive pharmaceutical (Paracetamol; 0 and 250 mg L−1) and amino acid (0 and 4 ml/L) on the growth, physiology, and yield of B. napus under drought stress. Seedlings were subjected to varying levels of drought stress (100% field capacity (FC; control) and 50% FC). Sole amino acid application significantly improved chlorophyll content, proline content, and relative water contents, as well as the activities of antioxidative enzymes (such as superoxide dismutase and catalase) while potentially decreased malondialdehyde and hydrogen peroxide contents under drought stress conditions. Pearson correlation analysis revealed strong positive correlations between these parameters and seed yield (R2 = 0.8–1), indicating their potential to enhance seed yield. On the contrary, sole application of paracetamol exhibited toxic effects on seedling growth and physiological aspects of B. napus. Furthermore, the combined application of paracetamol and amino acids disrupted physio-biochemical functions, leading to reduced yield. Overall, sole application of amino acids proves to be more effective in ameliorating the negative effects of drought on B. napus.

Elevated CO2 improves grain yield in bread wheat by enhancing carbon assimilation, activities of carbohydrate metabolic and antixidant enzymes

This study aimed to explore the effects of elevated CO2 (e[CO2]) on wheat performance under drought stress, while investigating the role of eco-physiology, carbohydrate metabolic and antioxidant enzymes to predict the grain yield. Wheat genotype Lianmai6 was grown under ambient (400 ppm) and elevated (800 ppm) CO2 concentrations, with subsequent exposure to drought stress prior to anthesis. Leaf parameters, including photosynthetic rate (An), stomatal conductance (Gs), and transpiration rate (E), were significantly declined under drought. Grain yield parameters were adversely affected by drought stress, while An with water use efficiency (WUE) and yield traits increased under e[CO2]. Notably, the activities of certain carbohydrate metabolic enzymes were increased in sink tissues but reduced significantly in source tissues under drought conditions. However, activities phosphoglucomutase (PGM and phophoglucoisomerase (PGI) were increased in source tissues under the combined effect of drought and e[CO2]. Total antioxidant potential (TAP) decreased in both leaf and spike under drought conditions, yet increased significantly under e[CO2]. These findings suggest that e[CO2] can enhance CO2 assimilation by boosting antioxidant potential and facilitate increased supply of photosynthates through enhanced activities of various carbohydrate metabolic enzymes, ultimately the better grain yield. These findings could elucidate the partial mechanism of better grain yield in bread wheat under combined effect of e[CO2] and drought stress.