Drought Stress Research Articles

Overexpression of MtIPT gene enhanced drought tolerance and delayed leaf senescence of creeping bentgrass (Agrostis stolonifera L.)

BackgroundIsopentenyltransferases (IPT) serve as crucial rate-limiting enzyme in cytokinin synthesis, playing a vital role in plant growth, development, and resistance to abiotic stress.ResultsCompared to the wild type, transgenic creeping bentgrass exhibited a slower growth rate, heightened drought tolerance, and improved shade tolerance attributed to delayed leaf senescence. Additionally, transgenic plants showed significant increases in antioxidant enzyme levels, chlorophyll content, and soluble sugars. Importantly, this study uncovered that overexpression of the MtIPT gene not only significantly enhanced cytokinin and auxin content but also influenced brassinosteroid level. RNA-seq analysis revealed that differentially expressed genes (DEGs) between transgenic and wild type plants were closely associated with plant hormone signal transduction, steroid biosynthesis, photosynthesis, flavonoid biosynthesis, carotenoid biosynthesis, anthocyanin biosynthesis, oxidation-reduction process, cytokinin metabolism, and wax biosynthesis. And numerous DEGs related to growth, development, and stress tolerance were identified, including cytokinin signal transduction genes (CRE1, B-ARR), antioxidase-related genes (APX2, PEX11, PER1), Photosynthesis-related genes (ATPF1A, PSBQ, PETF), flavonoid synthesis genes (F3H, C12RT1, DFR), wax synthesis gene (MAH1), senescence-associated gene (SAG20), among others.ConclusionThese findings suggest that the MtIPT gene acts as a negative regulator of plant growth and development, while also playing a crucial role in the plant’s response to abiotic stress.

The flower does not open in the city: evolution of plant reproductive traits of Portulaca oleracea in urban populations.

The impact of urbanization on plant evolution, particularly the evolution of reproductive traits, remains largely unknown. In this study, we aimed to investigate the consequences of urbanization on the reproductive traits of Portulaca oleracea in the Kantō region of Japan. Portulaca oleracea has a unique cleistogamous reproductive system, which consists of genetically determined chasmogamous (open, CH) and cleistogamous (closed, CL) plants. We collected seeds of P. oleracea from ten populations in rural areas and ten populations in urban areas. In a common garden experiment, we recorded the type of flowers (CH or CL), reproductive phenology and seed production. All individuals produced either CH or CL flowers, allowing us to classify them as either CH or CL plants. We observed a significant difference in the prevalence of CH and CL plants between rural and urban populations: the number of CH plants was generally low and was particularly low among urban individuals. Compared to CH plants, CL plants showed earlier phenology and produced heavier seeds, which is consistent with stress avoidance in response to heat and drought stress conditions in urban areas. Our findings suggest that urbanization may drive an evolutionary change in the cleistogamous reproductive system of P. oleracea. CL plants with earlier phenology and larger seeds might be better adapted to urban environments, where they are subjected to harsh heat and drought stress.

Assessing the impact of early and terminal droughts on root growth, grain yield and yield stability in old and modern wheat cultivars on the Loess Plateau

Understanding changes in root traits of high-yielding genotypes that consistently perform during different drought periods is crucial for improving wheat production and yield stability. A 2-year field trial and a pot experiment were conducted to determine the response of root growth and grain yield to early and terminal droughts in old and modern cultivars (FC3: 1960s and CH1: 2010s) under rainfed and irrigated conditions in the field. Rainfed wheat faced terminal drought in 2015-2016 and early drought in 2016-2017. Plants in the pot experiment were exposed to terminal drought, early drought, and well-watered. Both field and pot experiments showed higher grain yield in modern cultivar CH1 compared to FC3. Early and terminal droughts reduced grain yield in both cultivars, with a greater reduction in FC3. CH1 exhibited higher yield stability under drought conditions and experienced less reduction in early drought. Compared to FC3, CH1 produced more root biomass in the early growth stage. At anthesis, CH1 had significantly lower root biomass and root length density in the topsoil layer (00.2m) and higher in the subsoil layer (0.21.0m) than FC3, respectively. At maturity, the retention rate of subsoil root biomass in CH1 was higher, especially under early drought (80.2% in field and 93.9% in pot experiments). Both cultivars consumed similar seasonal water use, but CH1 reduced pre-anthesis water use and consumed more water after anthesis. This study indicates that modern cultivar had vigorous root growth at early stage. A higher proportion of root biomass preserved in deep soil after anthesis enhanced post-anthesis water use and photosynthetic rate, improved post-anthesis dry matter accumulation, and thus resulted in higher thousand kernel weight. These factors ensure higher yield and yield stability under both early and terminal drought stress.

Plant growth promoting rhizobacteria (PGPR) application for coping with salinity and drought: a bibliometric network multi-analysis.

Rhizobacteria play a crucial role in plant growth and yield, stimulating primary production and improving stress resistance. Climate change has several consequences worldwide that affect arable land and agriculture. Studies on plant-soil-microorganism interactions to enhance plant productivity and/or resistance to abiotic stress may open new perspectives. This strategy aims to make agricultural-relevant plant species able to complete their biological cycle in extreme soils with the help of inoculated or primed plant growth-promoting rhizobacteria (PGPR). We provide an overview of the evolution of interest in PGPR research in the last 30 years through: (i) a quantitative search on the Scopus database; (ii) keyword frequencies and clustering analysis, and (iii) a keyword network and time-gradient analysis. The review of scientific literature on PGPR highlighted an increase in publications in the last 15 years, and a specific time gradient on subtopics, such as abiotic stresses. The rise in PGPR as a keyword co-occurring with salinity and drought stresses aligns with the growing number of papers from countries directly or partly affected by climate change. The study of PGPR, its features, and related applications will be a key challenge in the next decades, considering climate change effects on agriculture. The increased interest in PGPR leads to deeper knowledge focused specifically on researching agriculturally sustainable solutions for soils affected by salinity and drought.

Effects of drought and moisture stress on the growth and ecophysiological traits of Schima superba seedlings.

Changes in rainfall patterns are important environmental factors affecting plant growth, especially when larger precipitation events and prolonged drought periods occur in subtropical regions. There are many studies on how drought reduces plant biomass through drought-sensitive functional traits, but how excess water affects plant growth and ecophysiology is still poorly understood. Therefore, a greenhouse experiment was conducted on Schima superba (Theaceae), a dominant tree species in subtropical forests and commonly used in forestry, in a closed chamber under control (25% soil water content (SWC) as in local forests), drought stress (D, 15% SWC) and moisture stress (W, 35% SWC). Plant growth and ecophysiological traits related to morphology, leaf gas exchange, water potential and structural traits were measured. Compared to control, S. suberba under dry conditions significantly decreased its aboveground biomass, photosynthetic rate (A), leaf water potential and nitrogen use efficiency, but increased intrinsic water use efficiency, root to shoot ratio and specific root length. S. superba under wet conditions also significantly decreased its total biomass, aboveground biomass and specific root length, while W had no effect on A and leaf water potential. Our results indicate that S. superba shows a decrease in carbon gain under drought stress, but less response under wet conditions. This emphasizes the need to consider the strength and frequency of rainfall pattern changes in future studies because rainfall may either alleviate or intensify the effects of drought stress depending on the moisture level, thus suitable water conditions is important for better management of this tree species in subtropical China.

Transcription factor NAC78 cooperates with NAC78 INTERACTING PROTEIN6 to confer drought tolerance in rice.

NAC (NAM, ATAF1/2, and CUC2) family transcription factors are involved in several cellular processes, including responses to drought, salinity, cold, and submergence. However, whether or how certain NAC proteins regulate drought tolerance in rice (Oryza sativa) remain unclear. In this study, we show that over-expression of OsNAC78 enhanced rice resistance to drought treatment, whereas Osnac78 mutant plants were susceptible to drought stress. We further characterized the OsNAC78 interacting protein, named NAC78 interacting protein6 (OsNACIP6), and found that it conferred rice drought tolerance. Our results demonstrate that OsNACIP6 enhanced transcription of OsNAC78 and promoted the expression of its downstream target OsGSTU37, encoding a glutathione reductase. The ABRE4 cis-element in the promoter region of OsNACIP675-1-127 conferred significant up-regulation of OsNACIP6 expression and initiated the OsNACIP6/OsNAC78-OsGSTU37 module that facilitates rice growth under drought conditions. Together, our results uncover a transcriptional module composed of OsNACIP6, OsNAC78, and OsGSTU37 and provide insights into the molecular mechanisms underlying the drought stress response in rice.

Exogenous Silicon and Salicylic Acid Applications Enhance Growth, Yield, and Physiological Traits of Cotton Plants under Drought Stress

Exogenous Silicon and Salicylic Acid Applications Enhance Growth, Yield, and Physiological Traits of Cotton Plants under Drought Stress

Identification of DREB Family Genes in Banana and Their Function under Drought and Cold Stress

Identification of DREB Family Genes in Banana and Their Function under Drought and Cold Stress

Direct and mediated impacts of mixed forests on Norway spruce infestation by European bark beetle Ips typographus

Climate change-induced windfalls and droughts exacerbate bark beetle outbreaks, severely impacting forest ecosystems. Despite extensive research on bark beetle infestation patterns, the question regarding the optimal spatial grid (SG) size for analyzing this phenomenon remains unresolved. The protective potential of natural forest complexity against bark beetles has been underestimated. We used remotely sensed data to fit Generalized Linear Models and structural equation models to explore the direct and environment-mediated effects of mixed forest cover (MFC) on Norway spruce forest infestation in central Europe. We assessed the effectiveness of various spatial grids (from 100 m to 1 km) for studying infestation by Ips typographus. We found a strong non-linear decline in infestation with increasing MFC across different spatial scales. The relationship between infestation and temperature was positive, while elevation had a negative effect on infestation, with higher infestation rates observed below 900 m. Direct effects of environmental predictors on infestation were significant at SGs of 100 m, 300 m, 400 m, and 500 m, but insignificant at 200 m and 1000 m SGs. Slope positively influenced infestation at 300 m and 400 m SGs. MFC exhibited significant indirect effects on infestation mediated by elevation, temperature, potential evapotranspiration, slope, and heat load index. Landscape variables played a significant role in the models at high-resolution spatial grids, whereas climate variables were influential in models at lower spatial grids of infestation data. We argue that mixed forest facilitates cooling, preserves water, enriches symbiotic fungal community, alleviating tree drought stress and mitigating infestation risk. Broad-leave trees’ non-host volatiles presumably disrupt olfactory signals, impeding beetles’ ability to locate host trees effectively. Our results underscore the potential of increasing mixed forest cover as a self-sustainable silvicultural measure for forest protection against I. typographus and for mitigating the effects of climate change.

Genome-wide identification and evolution of the SAP gene family in sunflower (Helianthus annuus L.) and expression analysis under salt and drought stress

Stress-associated proteins (SAPs) are known to play an important role in plant responses to abiotic stresses. This study systematically identified members of the sunflower SAP gene family using sunflower genome data. The genes of the sunflower SAP gene family were analyzed using bioinformatic methods, and gene expression was assessed through fluorescence quantification (qRT-PCR) under salt and drought stress. A comprehensive analysis was also performed on the number, structure, collinearity, and phylogeny of seven Compositae species and eight other plant SAP gene families. The sunflower genome was found to have 27 SAP genes, distributed across 14 chromosomes. The evolutionary analysis revealed that the SAP family genes could be divided into three subgroups. Notably, the annuus variety exhibited amplification of the SAP gene for Group 3. Among the Compositae species, C. morifolium demonstrated the highest number of collinearity gene pairs and the closest distance on the phylogenetic tree, suggesting relative conservation in the evolutionary process. An analysis of gene structure revealed that Group 1 exhibited the most complex gene structure, while the majority of HaSAP genes in Group 2 and Group 3 lacked introns. The promoter analysis revealed the presence of cis-acting elements related to ABA, indicating their involvement in stress responses. The expression analysis indicated the potential involvement of 10 genes (HaSAP1, HaSAP3, HaSAP8, HaSAP10, HaSAP15, HaSAP16, HaSAP21, HaSAP22, HaSAP23, and HaSAP26) in sunflower salt tolerance. The expression of these 10 genes were then examined under salt and drought stress using qRT-PCR, and the tissue-specific expression patterns of these 10 genes were also analyzed. HaSAP1, HaSAP21, and HaSAP23 exhibited consistent expression patterns under both salt and drought stress, indicating these genes play a role in both salt tolerance and drought resistance in sunflower. The findings of this study highlight the significant contribution of the SAP gene family to salt tolerance and drought resistance in sunflower.

Identification of Drought Tolerant Chickpea Genotypes under Simulated Drought

Chickpea (Cicer arietinum L.) is one of the most important legume crops worldwide, with high protein content. Chickpea productivity is highly threatened by abiotic stresses, of which drought exerts the most crucial role in terms of growth inhibition and yield losses encountered. Since germination is a critical stage that is negatively affected by drought, an experiment was conducted to estimate the genotypic variability among 27 chickpea genotypes and to determine the seed germination and seedling growth ability under water stress conditions. Seeds were subjected to water stress by using polyethylene glycol (PEG-6000) at five stress levels (0, 5, 10, 15 and 20 % PEG). Among the genotype DIBG 205 (94.50%) recorded highest germination percentage compared to other genotypes. Root length recorded was highest in ICCV 4958 (18.48 cm) under 10% PEG -6000 and decreased with increase in osmotic stress. Drought significantly affected germination as well as all other associated traits with the effects of stress being analogous to the stress level applied. Seedling vigour index is a suitable selection criterion for drought tolerance, high seedling vigour index was observed in DIBG 205 and ICCV 4958 showing increased drought tolerance at high stress level, whereas low seedling vigour index was recorded in ICCV 201217 and ICCV 201116 indicating their possible exploitation as valuable genetic material for further breeding programs for drought tolerance.

Impact of high temperature and drought stress on the microbial community in wolf spiders

High temperatures and drought present significant abiotic challenges that can limit the survival of many arthropods, including wolf spiders, which are ectothermic and play a crucial role in controlling pest populations. However, the impact of these stress factors on the microbiota of spiders remains poorly understood. In this study, we utilized 16 S rRNA gene sequencing to explore the diversity and composition of bacterial communities within Pardosa pseudoannulata under conditions of high temperature and drought stress. We found that Firmicutes, Bacteroidetes, and Proteobacteria were the predominant bacterial phyla present. Analyses of alpha diversity indicated an increase in bacterial diversity under combined stress conditions, as reflected by various diversity indices such as Ace, Chao1, Shannon, and Simpson. Furthermore, co-occurrence network analysis highlighted intricate interactions among the microbial taxa (e.g., Enterobacter, Chitinophaga, and Eubacterium), revealing the adaptive complexity of the spider's microbiome to environmental stress. Functional prediction analysis suggested that combined stress conditions might enhance key metabolic pathways, particularly those related to oxidative phosphorylation and amino acid metabolism. Using Random Forest analysis, we determined that changes in three heat shock proteins were largely attributed to variations in bacterial communities, with Firmicutes being notably influential. Collectively, this in-depth analysis offers novel insights into the responses of microbial communities within spider microbiomes to combined abiotic stresses, providing valuable information for understanding extreme climate impacts and informing ecological management strategies.

Effects of Drought Stress on Photosynthesis and Chlorophyll Fluorescence in Blue Honeysuckle

Blue honeysuckle (Lonicera caerulea L.) is a deciduous shrub with perennial rootstock found in China. The objectives of this study were to explore the drought tolerance of blue honeysuckle, determine the effect of drought stress on two photosystems, and examine the mechanism of acquired drought tolerance. In this study, blue honeysuckle under four levels of simulated field capacity (100%, 85%, 75%, and 65% RH) was grown in split-root pots for drought stress treatment, for measuring the changes in chlorophyll content, photosynthetic characteristics, and leaf chlorophyll fluorescence parameters. The chlorophyll content of each increased under mild stress and decreased under moderate and severe stress. The net photosynthetic rate, transpiration rate, intercellular carbon dioxide concentration, and stomatal conductance of blue honeysuckle decreased with the increase in water stress. However, the water utilization rate and stomatal limit system increased under mild and moderate stress and decreased under severe stress. The maximum fluorescence (Fm), maximum photochemical efficiency, and quantum efficiency of photosystem II decreased with the decrease in soil water content, and the initial fluorescence increased significantly (p < 0.01). With the decrease in soil water content, the energy allocation ratio parameters decreased under severe drought stress. The main activity of the unit reaction center parameters first increased and then decreased. ABS/CSm, TRo/CSm, ETo/CSm, and REo/CSm gradually declined. After a comprehensive analysis, the highest scores were obtained under adequate irrigation (CK). Overall, we concluded that the water irrigation system of blue honeysuckle should be considered adequate.

Alleviation of Drought Stress in Soybean [Glycine max (L.) Merril] by Foliar Application of Thiourea on Productivity and Profitability under Rainfed Condition

Background: In changing climatic scenario, plants often face periods of soil and atmospheric water deficits because of scarcity of water availability and deteriorating quality across the globe. Drought stress is the one of the major abiotic factors that reduce plant water status, obstructs photosynthesis, brings oxidative stress hindering soybean productivity. In view of this, bioregulators (thiourea) are innovative agricultural technique used to protect plants, minimizing the adverse effects caused by environmental stress. Therefore, an alternative to improve crop yield under rainfed condition by application of bioregulators like thiourea and suitable varieties are important in order to mitigate stress in soybean production. Methods: The field experiments were conducted in Factorial RBD with three replications. To know the impact of foliar spray of thiourea on growth, physiological parameters, yield parameters, yield and economics of two soybean varieties were carried out during kharif 2020, 2021 and 2022. Result: Long term results showed that, by using MACS 1188 variety of soybean and foliar spray of thiourea at 500 ppm and 750 ppm during the 25 and 55 DAS is a commendatory option and most remunerative for farmers to improve the productivity and profitability of soybean in Northern Transition Zone of Karnataka.

The bryophyte rhizoid-sphere microbiome responds to water deficit.

The roots of vascular plants are colonised by a multitude of microbes, which play an important role in plant health and stress resilience. Drought stress in particular is devastating for crop yield and causes major shifts in the rhizosphere microbial communities. However, the microbiome associated to the rhizoids (hereafter termed rhizoid-sphere) of the nonvascular bryophytes remains largely unexplored. Here, we use amplicon sequencing to explore the rhizoid-sphere microbiome of three bryophyte species under drought and well-watered conditions. Comparing rhizoid-sphere microbial communities associated with the two liverworts Marchantia polymorpha and Marchantia paleacea and the moss Physcomitrium patens showed characteristic differences in composition between host species and both conserved and unique changes under drought. At phylum level, these changes were similar to changes in the rhizosphere of angiosperms under drought. Furthermore, we observed strong differences in rhizoid-sphere colonisation between bryophyte species for taxa known for nitrogen fixation and plant growth promotion. Interestingly, M. polymorpha prioritised the growth of belowground organs under osmotic stress, as is the case for angiosperms under drought. Taken together, our results show interesting parallels between bryophytes and angiosperms in the relation with their rhizo(id-)sphere, suggesting evolutionary conservation among land plants in their response to drought stress.

UGT gene family identification and functional analysis of HvUGT1 under drought stress in wild barley

UGT gene family identification and functional analysis of HvUGT1 under drought stress in wild barley

Comparative Effects of Water Scarcity on the Growth and Development of Two Common Bean (Phaseolus vulgaris L.) Genotypes with Different Geographic Origin (Mesoamerica/Andean)

Drought stress is widely recognized as a highly detrimental abiotic stress factor that significantly impacts crop growth, development, and agricultural productivity. In response to external stimuli, plants activate various mechanisms to enhance their resistance or tolerance to abiotic stress. The common bean, a most important legume according to the FAO, serves as a staple food for millions of people worldwide, due to its rich protein, carbohydrate, and fiber content, concurrently, and water scarcity is the main factor limiting common bean production. The process of domestication and on-farm conservation has facilitated the development of genotypes with varying degrees of drought stress resistance. Consequently, using landraces as biological material in research can lead to the identification of variants with superior resistance qualities to abiotic stress factors, which can be effectively integrated into breeding programs. The central scope of this research was to find out if different geographic origins of common bean genotypes can determine distinct responses at various levels. Hence, several analyses were carried out to investigate responses to water scarcity in three common bean genotypes, M-2087 (from the Mesoamerican gene pool), A-1988 (from the Andean gene pool) and Lechinta, known for its high drought stress resistance. Plants were subjected to different water regimes, followed by optical assessment of the anatomical structure of the hypocotyl and epicotyl in each group; furthermore, the morphological, physiological, and biochemical parameters and molecular data (quantification of the relative expression of the thirteen genes) were assessed. The three experimental variants displayed distinct responses when subjected to 12 days of water stress. In general, the Lechinta genotype demonstrated the highest adaptability and drought resistance. The M-2087 landrace, originating from the Mesoamerican geographic basin, showed a lower resistance to water stress, compared to the A-1988 landrace, from the Andean basin. The achieved results can be used to scale up future research about the drought resistance of plants, analyzing more common bean landraces with distinct geographic origins (Mesoamerican/Andean), which can then be used in breeding programs.

Effect of Planting Ground Treatments Using Artificial Rainfall Slope Simulating Degraded Forestland on Drought Stress Susceptibility of Pinus densiflora

Trees in degraded forest areas are generally exposed to water stress due to harsh environmental conditions, threatening their survival. This study simulated the environmental conditions of a degraded forest area by constructing an artificial rainfall slope and observing the physiological responses of Pinus densiflora to control, mulching, and waterbag treatments. P. densiflora exhibited distinct isohydric plant characteristics of reducing net photosynthetic rate and stomatal transpiration rate through regulating stomatal conductance in response to decreased soil moisture, particularly in the control and waterbag treatments. Additionally, the trees increased photochemical quenching, such as Y(NPQ), to dissipate excess energy as heat and minimize damage to the photosynthetic apparatus. However, these adaptive mechanisms have temporal limitations, necessitating appropriate measures. Under extreme drought stress (DS45), mulching treatment showed 4.5 times and 2.2 times higher in PIabs and SFIabs than in the control, and after the recovery period (R30), waterbag and mulching treatment showed similar levels, while PIabs and SFIabs in the control were only 45% and 75% of those in the mulching and waterbag treatments, respectively. Specifically, mulching extended the physiological mechanisms supporting survival by more than a week, making it the most effective method for enhancing the planting ground in degraded forest areas. Although the waterbag treatment was less effective than mulching treatment, it still significantly contributed to forming better growth conditions compared to the control. These findings highlight the potential for mulching and waterbag treatments to enhance forest restoration efforts, suggesting future research and application could lead to more resilient reforested areas capable of withstanding climate change-induced drought conditions.

Genome-wide identification, abiotic stress, and expression analysis of PYL family in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) during grain development

BackgroundAbscisic acid (ABA) is a plant hormone that plays an important role in plant resistance to drought, salinity, cold, and pathogens. It is also important for regulating plant growth and development. Pyrabactin resistance/pyr1-like/regulatory components of the ABA receptor (PYL/RCAR) are ABA receptor proteins in plants and the core of ABA signal transduction pathways in plant regulatory factors. At present, there are no reports on the PYL family of Tartary buckwheat.ResultsIn this study, 19 paralogous form PYL genes in buckwheat were identified at the whole-genome level and named FtPYL1-FtPYL19 according to their positions on chromosomes. We further analyzed the gene structure, conserved motifs, cis-acting elements, gene duplication, phylogenetic relationships, and expression patterns under different stress treatments and during grain development of the 19 paralogous form PYL genes in Tartary buckwheat. The FtPYL gene exhibits a single exonic gene structure for about 68.4% of the duplicated forms from the total paralogous forms. The remaining subfamilies, such as I and II, contain three exons and two exons (e.g., FtPYL19), respectively. Nineteen FtPYL genes were evenly distributed across the eight chromosomes, with at least one FtPYL gene on each chromosome. In the FtPYL gene family, there was one tandem repeat event and five gene duplication events. We investigated the gene expression levels of FtPYL gene under four abiotic stresses and different stages of grain development. Under drought stress (PEG6000), the relative expression levels of FtPYL14 and FtPYL15 increased by fourfold. Under high temperature stress (38℃), the relative expression level of FtPYL16 dropped to 0.12, and that of FtPYL17 fell to 0.22. At different stages of grain development, the gene expression level of FtPY15 is extremely high at 19 D. The relative expression level of FtPYL7 in roots and stems reaches up to approximately 450, and the relative expression level of FtPYL10 in 13 D also reaches up to 248.SummaryIn this study, the PYL gene family of Tartary buckwheat was identified and analyzed based on the whole genome, and 19 paralogous form FtPYL genes of Tartary buckwheat were bioinformatically analyzed. The expression patterns of 19 paralogous form FtPYL genes in Tartary buckwheat cultivars under different stress treatments and during grain development were analyzed. It was found that the FtPYL gene played an important role in grain development.

Genetic Evaluation of Heterosis and Combining Ability of Quality Protein Maize (Zea mays L.) Hybrids under Terminal Heat Stress Conditions

Background: The development of quality protein maize (QPM) hybrids tolerant to terminal stress environments has been an essential strategy for reducing the associated loss in grain yield. A study by Badu-Apraku et al., (2019) employed line × tester analysis in QPM breeding, highlighting its efficacy in selecting QPM hybrids. While QPM varieties resistant to disease, drought and environmental stresses have been developed conventionally, the adoption of improved QPM genotypes in farmers’ field is restricted mainly due to lack of proper team effort among maize breeders, farmers, agricultural extension workers and other relevant stakeholders. Methods: In line × tester mating design, six lines and three testers were crossed under heat stress environment and 18 F1s along with parental lines were evaluated along with check varietal during summer season, 2023, P.G research farm, CUTM, Paralakhemudi, Odisha. The objective of the current study was to evaluate parental lines and its crosses based on combining ability and heterosis. Result: ANOVA revealed significant to revealed significant differences for all the traits between parents, lines, testers and lines vs testers, except for cob height, chlorophyll content and canopy temperature. 𝛔2GCA/𝛔2SCA values for parents/hybrids recorded lower than unity for all the trait studied suggesting preponderance of non-additive gene action. Parental lines CML149, CML143 and CML330 are the best general combiners for early flowering, grain yield per plant and antioxidant status. Among eighteen crosses, two hybrids CML149 × CML330 and CML143 × CML193 recorded significant SCA effects for early flowering, grain yield per plant and antioxidant levels. Hybrids CML149 × CML330 (33.31%) and CML143 × CML193 (28.31%) noted significant standard heterosis for grain yield per plant over commercial check, HQPM-1. Hybrids CML149 × CML330 and CML143 × CML193 were resilient to terminal heat stress as they didn’t exhibit signs of leaf firing, tassel blast, root lodging and loss of yield.