Terminal Heat Stress Research Articles

Identification of heat tolerant lentil genotypes through stress tolerance indices

With climate change projections indicating an increase in the frequency of extreme heat events and irregular rainfall patterns globally, the threat to global food security looms large. Terminal heat stress, which occurs during the critical reproductive stage, significantly limits lentil productivity. Therefore, there is an urgent need to improve lentil’s resilience to heat stress to sustain production. However, studies identifying heat-tolerant sources in lentils are limited. To address these issues, we assessed 158 lentil genotypes under normal and late-sown conditions over two consecutive seasons. We employed eleven heat stress indices to identify lines tolerant to heat stress. All genotypes exhibited a decrease in average grain yield when subjected to stress conditions as compared to non-stress conditions, indicating the impact of heat stress on crop yield. Correlation analysis showed significant positive correlation between yield in normal and late-sown conditions and the following heat stress indices: STI, MP, MRP, YI, GMP, and HM. In contrast, TOL, SSPI, and PYR showed negative associations with yield in late-sown conditions. Based on these indices, we identified the genotypes P13143, P13130, and P13135 as high-yielding in both stress and non-stress conditions. Cluster analysis and biplot display in PCA also confirmed that genotypes P13143, P13130, and P13135 exhibited suitability and high yield potential in both environments. These genotypes can be utilized as donors in future breeding programs to introduce genetic variations for improving heat stress tolerance in lentil.

Characterization of Canopy Temperature in Bread Wheat Genotypes under Terminal Heat Stress

Characterization of Canopy Temperature in Bread Wheat Genotypes under Terminal Heat Stress

Exploring Genetic Diversity in Wheat (Triticum aestivum L.) under Timely Sown and Terminal Heat Stress Conditions using Multivariate Approaches

Background: Wheat, a vital food crop, is increasingly threatened by heat stress due to climate change. This significantly impacts yields and grain quality. India, a major wheat producer, urgently needs heat tolerant varieties and late sown wheat is particularly susceptible to terminal heat stress. This study aimed to identify diverse heat tolerant genotypes among evaluated genotypes that can be used in further breeding programs. Methods: The study investigated genetic diversity in 29 wheat (Triticum aestivum L.) genotypes under timely and late sown environments at DRPCAU, Bihar during rabi 2020-21 by employing 11 morpho-physiological traits in Randomized Block Design. Multivariate approaches such as principal component analysis, genotype by trait biplot and cluster analysis were employed to categorize and identify the genotypes with desirable traits for heat tolerance. Result: Our study revealed a significant negative correlation between grain yield per plant and canopy temperature. Cluster analysis categorized genotypes into distinct groups under both timely and late sown conditions. The identified diverse lines from these clusters, exhibiting desirable traits, hold significant potential as parents for future breeding programs, emphasizing the crucial role of heat tolerance in wheat improvement.

Evaluation of physio-biochemical traits in bread wheat RILs for terminal heat stress

Evaluation of physio-biochemical traits in bread wheat RILs for terminal heat stress

The physio-biochemical impact of terminal heat stress on wheat varieties

The physio-biochemical impact of terminal heat stress on wheat varieties

Unravelling the photosynthetic dynamics and fluorescence parameters under ameliorative effects of 24-epibrassinolide in wheat (Triticum aestivum L.) grown under heat stress regime

An experiment was performed at the Banaras Hindu University, India to study the effect of terminal heat stress on photosynthetic dynamics and fluorescence parameters of wheat genotypes and ameliorative effects of epibrassinolide by taking two genotypes with four concentrations as foliar spray at two growth stages of wheat. The highest values were observed in plots foliar sprayed with 1.0 µM 24-epibrassinolide (T1) under normal conditions (D1) where the genotype Sonalika (V1) performed significantly well w.r.t. the parameters viz. steady-state fluorescence (Fs) 116.22, quantum efficiency of PSII 0.59, maximum fluorescence (Fm) 776.5, normalized stress detection ratio (Fv/Fo) 4.47, maximum potential quantum efficiency of PSII (Fv/Fm) 0.82.Whereas under heat stress condition (late sown D2), there was significant reduction in these parameters in both the genotypes which was improved by the application of epibrassinolide suggesting its potential role in improving the photoinhibition process by raising the efficiency of PSII. Overall, the calibrated application of 24-epibrassinolide was found to be a potent growth regulator involved in the positive modulation of heat stress tolerance in wheat, coupled with improved photosynthetic efficiency in treated plots as compared to control.

Performance of late sown wheat genotypes under drought stress at Khajura, Banke, Nepal

This study aimed to identify wheat genotypes tolerant to drought and terminal heat stress under late-sown conditions using stress tolerance indices. A field experiment was conducted with 18 genotypes, including checks, at the Directorate of Agricultural Research, Lumbini Province, Khajura, Banke. The trials were arranged in a randomized complete block design (RCBD) with three replications under two conditions: normal irrigated and simulated drought (via rainout shelter). Grain yield was recorded, and stress susceptibility and tolerance indices were estimated. The research showed that the average grain yield of all tested genotypes decreased by 58.8% under stress conditions compared to normal irrigated condition . There was a highly significant difference (p<0.01) in grain yield across genotypes when grown under both irrigated and stress conditions. The genotype NL 1488 produced the highest grain yield of 3725 kg/ha, followed by Banganga (3693.67 kg/ha), NL 1447 (3550.33 kg/ha), NL 1423 (3454.67 kg/ha), NL 1444 (3426 kg/ha), and NL 1445 (3224.67 kg/ha) under normal irrigated conditions. Similarly, the genotype NL 1447 produced the highest grain yield of 1547.33 kg/ha, followed by NL 1415 (1541.67 kg/ha), NL 1444 (1442.33 kg/ha), NL 1345 (1349.33 kg/ha), NL 1446 (1338.33 kg/ha), and NL 1451 (1328.33 kg/ha) under drought conditions. The highest values of MP, GMP, and STI were obtained in genotype NL 1447, followed by NL 1444, NL 1415, NL 1451, and NL 1446. Thus, these genotypes exhibit high yield potential under both irrigated and drought conditions, making them suitable candidates for breeding programs aimed at improving drought resilience in wheat.

Examine The Efficacy of Mannitol and Nano Urea in Alleviating the Negative Impacts of Terminal Heat Stress on Wheat (Triticum Aestivum L.)

Examine The Efficacy of Mannitol and Nano Urea in Alleviating the Negative Impacts of Terminal Heat Stress on Wheat (Triticum Aestivum L.)

Physiological and Yield Responses of Indian Mustard (Brassica juncea) to Terminal Heat Stress

In present investigation we studied the influence of terminal heat stress on several agronomic, physiological and yield-related variables in 10 mustard genotypes; Advance-414, Anmol, Bond, Coral-432, JKMS 8532, MRR-8030, NMS-2018, Rajshree, RH-30 and Sonalika. The experiment conducted under control condition (Sown in October) and heat stressed environment (Sown in November) to assess the role of ambient and high temperatures, respectively. Different characteristics including relative water content (RWC), water saturation deficit (WSD), relative dry weight (RDW), membrane stability index (MSI), days to flowering, plant height and yield attributes were analysed in respect to heat stress. The results demonstrated strong relationship between genotype and treatment in responses to heat stress. In terms of RWC, RH-30 maintained high value in both normal (95.17 ± 0.991%) and late sown (72.78 ± 1.022%) circumstances, but Coral-432 showed sensitivity to stress conditions with reduction in relative water content ranging from 80.91±0.085% in control environment to 51.30±0.988% in late sown condition. Heat stress significantly raised water saturation deficit in all genotypes, with RH-30 retaining lower WSD (4.83 ± 0.083%; control and 27.22±0.595% heat stress) than Coral-432 (19.08 ± 0.467% control and 48.70 ± 0.179% heat stress) whereas membrane stability index ranged from 5.03 ± 0.033% to18.03 ± 0.176%. Yield attributes such as seed yield per plant, test weight drastically reduced under heat stress whereas, genotype RH-30 showed resistance to stress and highest in seed yield (14.22 ± 0.215 g) and 1000-seed weight (test weight; 4.35 ± 0.066 g) under stress. Plant height and number of branches also showed similar reduction in respect to heat stress. Overall, genotypes RH-30 and Rajshree found superior to stress tolerance in all tested parameters and further used in the breeding programme to develop the heat resilience cultivar in mustard.

Physiological Adaptations of Vegetables to Climate Stress

Vegetables, being rich in vitamins, carbohydrates, minerals, proteins and antioxidants are essential for overcoming micronutrient deficiencies, offering higher incomes and more employment opportunities per hectare to smallholder farmers compared to staple crops. Major challenges faced by vegetable growers are increased terminal heat stress, rainfall variability leading to flooding, drought, irrigation water availability, salinity, incidence of pests and diseases, extreme weather events. These gets further worsened in the future due to climate change. Vegetables exhibit various physiological adaptations to cope with changing environmental conditions such as enhanced photosynthetic efficiency, improved water-use efficiency, and altered phenological development. Higher temperatures accelerate the life cycle of vegetables cause increased respiration, leading to earlier maturation and potentially lower yields. Increased frequency of heat waves can cause heat stress, affecting growth and development. Moreover elevated temperatures increase the incidence of pests and diseases, leading to higher crop losses. Changes in precipitation patterns alter water availability, impacting growth and productivity. Nevertheless drought conditions cause stomatal closure limiting water loss besides reducing CO2 uptake. Excessive rainfall can lead to waterlogging, disrupting root function and nutrient uptake. Variability in climate conditions lead to inconsistent yields, making it challenging for farmers and necessitating adaptive strategies to ensure crop resilience and productivity. Genetic improvement through breeding for heat and drought tolerance helps to develop resilient vegetables. Additionally, agronomic practices like mulching, organic farming, and resource conservation technologies help mitigate the adverse effects of climate change. Understanding these physiological responses could streamline sustainable vegetable production in the face of a changing climate.

Assessment of Terminal Heat Stress Tolerance in Doubled Haploids Derived from Synthetic Hexaploid Wheat (Triticum aestivum L.) Using Genetic Variability and PCA-based Cluster Analyses

A comprehensive study was conducted on germplasm derived from two synthetic wheats and two hexaploid wheats i.e., SHW14102 x BWL4444, SHW14102 x BWL3531, and SHW3761 x BWL4444 to identify the potential doubled haploids that can withstand high temperatures, particularly at the reproductive stage during crop seasons viz., 2020–2021 and 2021–2022. The doubled haploid lines were selected based on phenotypic characteristics using genetic variability analysis. In the preliminary field trial evaluation, 100 lines were selected based on high phenotypic uniformity for further testing against terminal heat stress conditions and high yield potential. Among these, 17 lines had relatively higher values for days to biomass yield, grain yield, thousand-grain weight, and harvest index and relatively lower values for maturity, and grain filling duration based on principal component and cluster analyses. Principal component analysis (PCA) based cluster analysis exhibited that, clusters II and III had clear separation compared to cluster I. All three clusters were analyzed according to their means and standard deviations. The mean values for GYP (385.07), BMYP (1162.37), and TGW (38.13) were relatively higher in cluster 1 than in other clusters. Cluster 2 exhibited a higher value for DH (89.14), SL with awns (18.21), and GFD (18.19) while cluster 3 showed a higher value for HI (41.02). Thus, it was concluded that cluster I demonstrated superior performance in grain yield per plant, biomass yield per plant, and thousand-grain weight, indicating its overall higher productivity compared to the other clusters under terminal heat stress conditions and suggesting them as potential germplasm for future breeding programs.

High temperature perturbs physicochemical parameters and fatty acids composition of safflower (Carthamus tinctorius L.)

Future climates will realise increasingly frequent extreme weather events, which will impact on the quantum and quality of crop production. While effects of extreme heat on crop production have been well studied hitherto, there remains a dearth of knowledge pertaining to the impacts of extreme heat on grain quality. As such, our purpose here was to evaluate the effects of terminal heat stress on the physicochemical properties and composition of seed oil of safflower plants. Using two contemporary cultivars with varying genetic tolerance to heat stress (Faraman and Sofeh), we found that exposure to extreme heat reduced grain yield by 53–57%. Four fatty acids (palmitic, stearic, oleic and linoleic acid) comprised 96–99% of total fatty acid methyl esters; relative composition varied in response to heat stress and other environmental conditions. In the first experimental year (2017-18), saturated fatty acids in Sofeh and Faraman cultivars increased by 69% and 18% respectively, while unsaturated fatty acids decreased by 9% and 4%, respectively. In the second experimental year (2018-19), saturated fatty acids increased by 10% in Sofeh and by less than 1% in Farman, while unsaturated fatty acids in both cultivars were not significantly altered. Physicochemical parameters differed across years and cultivars; exposure to high temperature increased chlorophyll and carotenoid content in Sofeh, but decreased the said parameters in Faraman. In 2017-18, effects of heat stress on thiobarbituric acid were variable, but in 2018-19, thiobarbituric acid increased in both cultivars. In all cases, saponification and iodine content increased in response to heat stress. In sum, the fatty acid profile of safflower exposed to terminal heat stress was less affected compared with oil physicochemical parameters, due to greater temperature sensitivity of the latter.

Evaluating stress tolerance indices for their comparative validity to access terminal heat stress and heat drought tolerance of winter wheat (Triticum aestivum L.) genotypes

Stress tolerance indices have been used to evaluate the performance and stability of elite wheat genotypes under non-stress and stress environments. From 1978 to present, many stress tolerance indices have been proposed but only few studies have been conducted so far for the comparative validity of those indices based on stress levels. The study focuses to address the comparative validity of those stress tolerance indices at two distinct stress level under mild stress-heat stress environment (∼20–25 % yield reduction) and high stress-heat drought environment (∼45–50 % yield reduction). Statistical tool such as correlation, linear regression, coefficient of determination (R2), slope of regression line and principal component analysis were performed for the study. Correlation and principal component analysis revealed that, indices such as modified stress tolerance indices (MSTI1), mean productivity (MP), geometric mean productivity (GMP), harmonic mean productivity (HMP), relative efficiency index (REI), mean relative performance (MRP) and modified stress indices 2 (MSTI2) were found to have strong positive association with wheat yield under non stress and stress environments at both levels. The coefficient of determination (R2) and slope of regression line revealed, MP and MSTI1 are the most predictive and explanatory indices under irrigated environment. While indices such as MRP, REI, yield index (YI) are most predictive and explanatory under mild stress-heat stress environment and GMP, HMP, mean stable yield (MSY), tolerance index (TOL), yield stability index (YSI), stress tolerance index (STI), MSTI2, stress susceptibility index (SSI), percentage yield loss (PYL), relative stress index (RSI) are appropriate under high stress-heat drought environment.

Enhanced climate change resilience on wheat anther morphology using optimized deep learning techniques.

Wheat commands attention due to its significant impact on culture, nutrition, the economy, and the guarantee of food security. The anticipated rise in temperatures resulting from climate change is a key factor contributing to food insecurity, as it markedly reduces wheat harvests. Terminal heat stress mostly affects spike fertility in wheat, specifically influencing pollen fertility and anther morphology. This research especially focuses on the shape of anthers and examines the effects of heat stress. The DinoLite Microscope's high-resolution images are used to measure the length and width of wheat anthers. By using object identification techniques, the research accurately measures the length and width of each anther in images, offering valuable insights into the differences between various wheat varieties. Furthermore, Deep Learning (DL) methodologies are utilized to enhance agriculture, specifically employing record categorization to advance plant breeding management. Given the ongoing challenges in agriculture, there is a belief that incorporating the latest technologies is crucial. The primary objective of this study is to explore how Deep Learning algorithms can be beneficial in categorizing agricultural records, particularly in monitoring and identifying variations in spring wheat germplasm. Various Deep Learning algorithms, including Convolution Neural Network (CNN), LeNet, and Inception-V3 are implemented to classify the records and extract various patterns. LeNet demonstrates optimized accuracy in classifying the records, outperforming CNN by 52% and Inception-V3 by 70%. Moreover, Precision, Recall, and F1 Measure are utilized to ascertain accuracy levels. The investigation also enhances our comprehension of the distinct roles played by various genes in abiotic stress tolerance among diverse wheat varieties. The outcomes of the research hold the potential to transform agricultural practices by introducing a more effective, data-driven approach to plant breeding management.

Characterization of Bread Wheat Genotypes Using SSR Markers for Terminal Heat Tolerance

Wheat is a major global food crop, but its productivity is increasingly threatened by terminal heat stress due to climate change. This study aimed to characterize the genetic diversity and heat tolerance of widely grown bread wheat genotypes using SSR markers to identify heat-tolerant cultivars adaptable to various regions in Bangladesh. A total of 15 genotypes were screened, and 13 polymorphic SSR (Simple Sequence Repeats) markers were used to determine the genetic similarity and categorize genotypes based on their heat tolerance. The molecular analysis revealed 13 polymorphic SSR markers that produced distinct PCR (Polymerase Chain Reaction) bands across the different genotypes. By the conclusion of the study, bread wheat genotypes were categorized as either tolerant or sensitive to heat, and the genetic similarity among the varieties was assessed using molecular markers. The genetic similarity coefficients obtained from the SSR primer screening ranged from 0.00 to 0.925. The lowest genetic distance (0.000) was found in Nadi 2 vs BAW1147 variety pair indicating that they are genetically similar to each other. Comparatively higher genetic distance (0. 925) was observed between BAW 1290 vs BARI Gom 28. The dendrogram divided the fifteen genotypes into two main groups, A and B, both formed at a similar coefficient of 0.05. Group A included seven genotypes and was further divided into two clusters, while Group B comprised eight genotypes, which were also divided into two clusters. The categorization of the genotypes was based on the average Heat Susceptibility Index (HSI), Thousand Grain Weight (TGW), grain yield, and the relative reduction in TGW and grain yield under stress conditions compared to timely sown conditions, aligning with the molecular data. Among the fifteen genotypes, BARI Gom 25, BARI Gom 26, BARI Gom 27, BARI Gom 28, BARI Gom 29, BARI Gom 30, and BARI Gom 31 demonstrated their adaptability to late sown conditions. The heat tolerance observed in these genotypes, as indicated by their SSR marker scores, is anticipated to provide valuable insights for molecular breeding studies focused on heat resistance.

AMMI and GGE Biplot Analysis for Selection of Some High Yielding Terminal Heat Stress Tolerant Wheat (Triticum aestivum) Genotypes in Bangladesh

AMMI and GGE Biplot Analysis for Selection of Some High Yielding Terminal Heat Stress Tolerant Wheat (Triticum aestivum) Genotypes in Bangladesh

Studies on Effect of Terminal Heat Stress on Seed Quality and its Mitigation in Chickpea (Cicer arietinum L.)

A field experiment was conducted to know the effect of terminal heat stress on seed yield and its mitigation in chickpea was carried out during 2021-22 at Seed Unit, University of Agricultural Sciences, Raichur. High temperature during sowing time from early to late and very late directly affect the vegetative and anthesis stages and it was overcome by spraying the plants with heat stress mitigating chemicals. The experiment was laid out with three dates of sowing and ten foliar spray each treatment was replicated twice in a split plot design. Spraying was done at two stages of crop growth i.e., at vegetative (35-40 DAS) and anthesis stage (50-60 DAS) in all dates of sowing. The interaction between dates of sowing and heat stress mitigating chemicals showed highest physiological and seed quality parameters i.e. chlorophyll stability index (D3T3) (73.06 and 74.63%), minimum cell membrane injury index (55.09 and 63.63 %), maximum proline content (D3T3) (6.79 and 9.37 µ mol g-1), relative water content (83.79 and 75.10 %) at 60 DAS and at harvest, first count (90.50 %), final count (100.00 %), speed of germination (43.80), minimum time for radicle emergence (41.00 hrs), root length (17.32 cm), shoot length (10.12 cm), dry weight (27.10 mg), seedling vigour index-I (2643), seedling vigour index-II (2700). Among the treatments, sowing done at October 15th and plants sprayed with salicylic acid @ 400 ppm followed by gibberellic acid (100ppm) (T10) twice at vegetative and anthesis stage was found to be better in obtaining significantly higher physiological and seed quality parameters in chickpea variety JG-11 under heat stress conditions.

Multi‐Environment Analysis of Nutritional and Grain Quality Traits in Relation to Grain Yield Under Drought and Terminal Heat Stress in Bread Wheat and Durum Wheat

ABSTRACTHeat and drought are two important constraints to global wheat productivity; understanding the genotypic responses for quality parameters under harsh production conditions (drought and heat) is very important for developing nutrient‐dense wheat varieties. A set of 15 modern bread wheat (Triticum aestivum L. subsp. aestivum) and durum wheat (Triticum turgidum subsp. durum) cultivars were tested in nine environments, including three different production conditions (normal, heat and drought) during 2020–21. Genotype stability performance for yield, nutrition and quality parameters is assessed using multienvironment trials through AMMI and GGE Biplot analysis. We discovered intriguing stress dynamics in grain zinc content (Zn) and grain iron content (Fe). Under heat stress, zinc concentration increases but decreases under drought stress, while iron does the opposite. Selecting zinc, starch and kernel weight under terminal heat stress can boost yield. Protein content and yield are inversely related, making it difficult for breeders to optimise both traits. G × E interactions and stability indices across all environments have found genotypes with high‐yielding stable genotypes, G12 (MP1358) (42.09 ppm) and G5 (HI1544) (42.41 ppm) have high Fe content. G12 (MP1358) (14.98%) ranked highest in protein concentration. Meanwhile, for Zn content, G11 (MACS 4058) (45.23 ppm) and G15 (WH730) (42.44 ppm) were top performers across environments. G7 (HI 1636) and G12 (MP1358) stand out as a win‐win genotype for their high potential and stability in yield, protein, Zn and Fe content. Our study shows the complex relationships and possible suggestions for targeted breeding programmes under heat and drought stress conditions to improve wheat grain quality and micronutrient profiles without yield loss.

Sweet Immunity in Action: Unlocking Stem Reserves to Improve Yield and Quality. A Potential Key Role for Jasmonic Acid.

Common agronomic practices such as stem topping, side branch removal, and girdling can induce wound priming, mediated by jasmonic acid (JA). Low light conditions during greenhouse tomato production make the leaves more sensitive to the application of exogenous sugar, which is perceived as a "danger" in accordance with the concept of "Sweet Immunity". Consequently, source-sink balances are altered, leading to the remobilization of stem starch reserves and enabling the redirection of more carbon toward developing fruits, thereby increasing tomato yield and fruit quality. Similarities are drawn with the mobilization of fructans following defoliation of fodder grasses (wounding) and the remobilization of fructan and starch reserves under terminal drought and heat stress in wheat and rice (microwounding, cellular leakage). A central role for JA signaling is evident in all of these processes, closely intertwining with sugar signaling pathways. Therefore, JA signaling, associated with wounding and sugar priming events, offers numerous opportunities to alter source-sink balances across a broader spectrum of agricultural and horticultural crops, for instance, through the exogenous application of JA and fructans or a combination. This may entail reconfiguring and reversing phloem connections, potentially leading to an enhanced yield and product quality. Such processes may also disengage the growth-defense trade-off in plants.

Conservation Tillage and In-Situ Rice Residue Driven soil Temperature Moderation and Wheat Productivity under Terminal Heat Stress in North-Western Indo Gangetic Plains of India

Conservation Tillage and In-Situ Rice Residue Driven soil Temperature Moderation and Wheat Productivity under Terminal Heat Stress in North-Western Indo Gangetic Plains of India