Heat Susceptibility Index Research Articles

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.

Assessment of genetic variability, heritability and correlation in advanced breeding lines of bread wheat (Triticum aestivum) under heat stress condition

Abstract An experiment was conducted under normal (with six irrigation during crop period) and stressed condition during Rabi 2019 in All India Coordinated Research Project (AICRP) on Wheat, MARS, Dharwad, Karnataka with the view of assessing genetic variability, heritability and expected genetic advance in 104 F4 families of the cross HD2864 × DBW14. The progenies exhibited wide range of variation for all the traits indicating the presence of enough genetic variability in the material under study. Under timely sown condition, the traits like leaf waxyness, NDVI at different stages, SPAD at different stages, number of productive tillers per plant, seeds per spike, grain filling duration, spike length, thousand grains weight and seed set percentage showed high variability. The traits like plant height, canopy temperature at different stages and membrane stability index showed low variability. Under late sown condition, the traits like leaf waxyness, plant height, NDVI at different stages, SPAD at different stages, number of productive tillers per plant, seeds per spike, yield per plant, row bulk yield and seed set percentage showed high variability. The traits like days to maturity, spike length and membrane stability index showed low variability. The findings shows that all traits related to crop yield are positively linked, except for canopy temperature at different growth stages. Promising lines identified through Heat susceptibility index (HSI) and Heat tolerance index (HTI) can be utilized in future breeding programs to enhance crop productivity. Keywords: Variability, Coefficient of variation, Heritability, Genetic advance.

DEVELOPMENT OF SELECTION CRITERIA FOR EVALUATION OF HOT PEPPER (CAPSICUM ANNUM L) GENOTYPE RESILIENT TO CLIMATE CHANGE

The hot pepper chilli, scientifically referred to as Capsicum spp., is globally recognized for its extensive use in cooking and industry. However, rising temperatures due to changing climate conditions are impacting crop yields by affecting pollen viability, as well as the setting and size of the fruit. To combat this, fifteen hot pepper genotypes were assessed to determine which one is most resilient to these climatic challenges. The results indicated that the VRIHP006 genotype exhibited the highest fruit setting and pollen viability percentage among the hot pepper genotypes, with an impressive 86% at optimal temperature and 36.4% under elevated temperatures followed by VRIHP001 and VRIHP004. The data of seed No. fruit-1, fruit length (cm), and fruit width (mm) manifested that genotypes that had less impact of temperature on fruit setting and pollen viability also maintained seed No. fruit-1, fruit length (cm) and fruit width. The Heat susceptibility indices also supported the above selection criteria.

Association Analysis in Rice Germplasm Lines for High Temperature Tolerance

Background: Relative to other abiotic factors like salinity and drought, breeding rice cultivars that are resistant of high temperatures has received a little attention. The purpose of this study is to find parents and genotypes that are suitable for utilizing in high temperature stress breeding program. Methods: The genetic material for this study comprised of a set of germplasm collections (293 accessions) from different sources such as International Rice Research Institute germplasm. These populations were raised at the Department of Rice, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore. The Heat tolarance Indices (TOL) viz., Heat tolerance index (HTI) and Heat susceptibility index (HSI) and association analysis were estimated among germplasm lines for yield attributes under normal and high temperature stress condition. Result: Out of 293 genotypes, sixty nine genotypes significantly exceeded for both HTI and HSI. Association studies revealed that, single plant yield had highly significant and positive association with panicle exertion, number of total tillers per plant, number of productive tillers per plant, panicle length, number of filled grains per panicle and total dry matter production. Spikelet sterility and high temperature susceptibility index had highly significant and negative association with single plant yield. Number of productive tillers had significant and positive correlation with total dry matter production, panicle length, number of filled grains per panicle, days to maturity, hundred grain weight, grain breadth and high temperature susceptible index. Hence these traits may be considered as selection indices for yield and high temperature tolerance improvement programme. Hence it may be possible to combine single plant yield and heat susceptibility index by specific breeding programme for high temperature tolerance in rice.

Screening and identification of heat tolerance in Indian wheat genotypes using generalized regression neural network (GRNN) model

The present study using a generalized regression neural network (GRNN) model was carried out to check the effect of high temperature on five Indian bread wheat genotypes, namely, C306, K7903, CBW12, HD2329, and HD2428, and to develop an algorithm for the screening and identification of heat tolerance in wheat. A highly significant differential survivability in response to the temperature induction response technique with germinating seeds was observed for the five wheat genotypes. Maximum survivability was observed for C306 and K7903, whereas HD2329 and HD2428 showed minimum survival in response to lethal temperature stress. Similarly, at the mature plant stage, in response to heat treatment of 34°C/26°C (day/night), all five wheat genotypes showed a significant difference in chlorophyll a fluorescence, total chlorophyll content, and the reduction of 1,1- diphenyl-2-picryl-hydrazyl (DPPH) in response to heat treatment. The genotypes, C306, K7903, and CBW12 showed better performance for all the chlorophyll a fluorescence parameters under study including Fo, Fv/Fm, qL, qP, NPQ, θPSII, ETR, along with the total chlorophyll content and DPPH reduction, in contrast, the genotypes, HD2329 and HD2428 performed poorly for all parameters including chlorophyll a fluorescence parameters, total chlorophyll, and DPPH reduction. Higher inflection temperature and peak temperature were observed in C306 and K7903, in contrast, HD2329 and HD2428 showed significantly lower inflection temperature and peak temperature. Higher expression of the selected genes involved in photosynthesis and ROS scavenging was observed in C306 and K7903 relative to HD2329 and HD2428. On the basis of the different chlorophyll a fluorescence parameters, the algorithm was developed for the calculation of the heat susceptibility index. The algorithm was independently checked for the identification and segregation of all the five wheat genotypes taken in this study as tolerant, moderate, and susceptible. For all the genotypes, the algorithm was able to predict the heat susceptibility of the genotypes with high accuracy. Hence, the algorithm in combination with chlorophyll a fluorescence can be used for the screening of wheat and other plant species in response to abiotic stress, especially heat stress.

The Response of Different Bread Wheat Genotypes (Triticum aestivum L.) to Temperature Changes

Increased temperature is a major yield declining factor in wheat production. Current study was intended to evaluate the impact of increased temperature on the pre and post reproductive major yield attributing biometrical traits through the use of stress tolerance indices and trait reduction ratio (%) of all the traits studied. A set of 27 genotypes including 2 check entries viz., Shriram 303 and HD 2967 was evaluated in two separate trials, timely sown (non-stress) and late sown (heat stress) conditions in RBD design with three replications during rabi 2020-21 at the agriculture research farm of Rama university, Kanpur. Significant dropping in major yield attributing traits have Such as grain yield/plant, grain yield/spike and tillers/plant exhibited 54.41%, 39.31 % and 34.22% reduction, respectively thought the estimation of trait reduction ration (%) specially for the trials conducted under the late sown (heat stress) condition as compared to the normal sown trial. Five stress tolerance indices viz., susceptibility index (HSI), mean productivity (MP), tolerance (TOL), heat tolerance index (STI) and trait stability index (TSI) have been estimated to find out the heat stress tolerance and susceptible genotypes for grain yield under high temperature stress conditions.
 Correlation estimates of different heat stress tolerance indices with grain yield in non-stress condition (timely sown) exhibited significant positive association with MP (0.766**), HTI (0.622**), TSI (0.414*), and TOL (0.284). Though, under heat stress condition (late sown), grain yield displayed a significant positive correlation with HTI (0.713**), MP (0.707**), TOL (0.517**), TSI (0.656**) and negative correlation with HSI (-0.608**). Through the correlation analysis estimates, four heat stress indices viz. HSI (heat susceptibility index), MP (mean productivity), STI (stress tolerance index) and TSI (trait stability index) have been used in assorting the heat tolerant wheat genotypes. Current estimates directed that 14 genotypes (PBW 152, HUW-206, WL-2, WL-8, WL-13, DBW-71, DBW-39, WH-1105, HUW-318, PBW-154, ALWL-5, WL-14, PBW-502 and Shriram 303) were heat tolerant genotypes while 8 genotypes (Jamuni, F 2004, Allahabad Local, Black, U. P Local, YOUDA, U. P B2425 and HD 2967) have been observed high temperature susceptible. While WH-1105 and PBW-154 have been observed high yielding genotypes under heat stress environment. Therefore, genotypes WH-1105 and PBW-154 were acknowledged as a suitable genotype for late sown trial. Further, these two genotypes could be utilize in breeding programme to develope heat tolerant varieties of wheat.

Heat tolerance indices as tools for characterizing resilient wheat (<i>Triticum aestivum</i>) RILs population under thermal stress

The escalating impact of heat stress on agriculture due to climate change has necessitated the development of heat- tolerant crop varieties. To address this, a study was carried out at research farm of CCS Haryana Agricultural University, Hisar, Haryana during winter (rabi) seasons of 2018–19 and 2019–20 under two different environments (normal and late sown). Evaluation of multiple stress indices and their relationship with grain yield per plot was done using 200 recombinant inbred lines (RILs) of wheat (Triticum aestivum L.). Positive correlation was observed between grain yield and stress tolerance index, mean productivity, geometric mean productivity, harmonic mean and mean relative performance, while negative correlations existed with heat susceptibility index, tolerance, stress susceptibility index and reduction under stress conditions. Stepwise regression analysis revealed the importance of mean productivity, yield index, geometric mean productivity, stress tolerance index, and reduction in predicting grain yield. Principal Component Analysis highlighted the significance of tolerance and reduction in explaining the variance, with PC-1 labeled as the resilience and stress tolerance component and PC-2 as the yield stability and performance component. These findings were able to select 13 most heat tolerant RILs, performing better than national level check genotype WH730 and emphasized the role of stress indices especially HSI and TOL in characterizing genotypic responses to heat stress and guiding the selection of heat-tolerant genotypes for sustainable crop improvement. In the context of heat stress tolerance, understanding and harnessing transgressive segregants could lead to the development of crop varieties that not only tolerate, but thrive in challenging environments, ensuring sustainable food production under changing climatic conditions.

Morpho-physiological diversity of Indian mustard (Brassica juncea L.) germplasm for terminal heat tolerance

Two hundred genotypes with seven checks of Indian mustard were sown at two different interval (timely and late) in augmented block design for trait association and comparative phenotyping against heat stress at terminal stage. Correlation studies revealed that seed yield per plant had significant positive association with plant height, number of primary branches per plant, number of secondary branches per plant, leaf area index, total number of siliqua per plant, siliqua on main shoot and 1000- seed weight under both normal and late sown conditions. Based on results of heat screening parameters like heat susceptibility index, yield stability index and percent yield change, genotypes viz. NDRE-4, EC-399300, DRMR-13, DRMR-9, DRMR-7, DRMR-357, DRMR-6, EC-766423 and IM76 were found promising for terminal heat tolerance.

A Multi-Model Based Stability Analysis Employing Multi-Environmental Trials (METs) Data for Discerning Heat Tolerance in Chickpea (Cicer arietinum L.) Landraces.

Identifying a congenially targeted production environment and understanding the effects of genotype by environmental interactions on the adaption of chickpea genotypes is essential for achieving an optimal yield stability. Different models like additive main effect and multiplicative interactions (AMMI 1, AMM2), weighted average absolute scores of BLUPs (WAASB), and genotype plus genotype-environment (GGE) interactions were used to understand their suitability in the precise estimation of variance and their interaction. Our experiment used genotypes that represent the West Asia-North Africa (WANA) region. This trial involved two different sowing dates, two distinct seasons, and three different locations, resulting in a total of 12 environments. Genotype IG 5871(G1) showed a lower heat susceptibility index (HSI) across environments under study. The first four interactions principal component axis (IPCA) explain 93.2% of variations with significant genotype-environment interactions. Considering the AMMI stability value (ASV), the genotypes IG5862(G7), IG5861(G6), ILC239(G40), IG6002(G26), and ILC1932(G39), showing ASV scores of 1.66, 1.80, 2.20, 2.60, and 2.84, respectively, were ranked as the most stable and are comparable to the weighted average absolute scores of BLUPs (WAASB) ranking of genotypes. The which-won-where pattern of genotype plus genotype-environment (GGE) interactions suggested that the target environment consists of one mega environment. IG5866(G10), IG5865(G9), IG5884(G14), and IG5862(G7) displayed higher stability, as they were nearer to the origin. The genotypes that exhibited a superior performance in the tested environments can serve as ideal parental lines for heat-stress tolerance breeding programs. The weighted average absolute scores of BLUPs (WAASB) serve as an ideal tool to discern the variations and identify the stable genotype among all methods.

Identification of heat tolerant bread wheat (Triticum aestivum L.) genotypes through heat susceptibility index (HSI) and SSR markers

Identification of heat tolerant bread wheat (Triticum aestivum L.) genotypes through heat susceptibility index (HSI) and SSR markers

Characterization of Traits Associated with Grain Yield Under Terminal Heat Stress in Bread Wheat (Triticum aestivum L.) on the Basis of Heat Susceptibility Index

Characterization of Traits Associated with Grain Yield Under Terminal Heat Stress in Bread Wheat (Triticum aestivum L.) on the Basis of Heat Susceptibility Index

Identification of Climate-Smart Bread Wheat Germplasm Lines with Enhanced Adaptation to Global Warming.

Bread wheat (Triticum aestivum L.) is widely grown in sub-tropical and tropical areas and, as such, it is exposed to heatstress especially during the grain filling period (GFP). Global warming has further affected its production and productivity in these heat-stressed environments. We examined the effects of heatstress on 18 morpho-physiological and yield-related traits in 96 bread wheat accessions. Heat stress decreased crop growth and GFP, and consequently reduced morphological and yield-related traits in the delayed sown crop. A low heat susceptibility index and high yield stability were used for selecting tolerant accessions. Under heatstress, the days to 50% anthesis, flag-leaf area, chlorophyll content, normalized difference vegetation index (NDVI), thousand grain weight (TGW), harvest index and grain yield were significantly reduced both in tolerant and susceptible accessions. The reduction was severe in susceptible accessions (48.2% grain yield reduction in IC277741). The plant height, peduncle length and spike length showeda significant reduction in susceptible accessions, but a non-significant reduction in the tolerant accessions under the heatstress. The physiological traits like the canopy temperature depression (CTD), plant waxiness and leaf rolling were increased in tolerant accessions under heatstress. Scanning electron microscopy of matured wheat grains revealed ultrastructural changes in endosperm and aleurone cells due to heat stress. The reduction in size and density of large starch granules is the major cause of the yield and TGW decrease in the heat-stress-susceptible accessions. The most stable and high-yielding accessions, namely, IC566223, IC128454, IC335792, EC576707, IC535176, IC529207, IC446713 and IC416019 were identified as the climate-smart germplasm lines. We selected germplasm lines possessing desirable traits as potential parents for the development of bi-parent and multi-parent mapping populations.

Genetic analysis of adaptive and physiological traits in response to high temperature stress in rapeseed

Diallel populations of rapeseed consisting of three yellow sarson (B9, YSH401 and NRCYS05-03) and two toria (Jeuti and TS46) parental lines were used for studying the genetic variation for physiological traits in response to high temperature screened under temperature gradient tunnel. Significant variation was observed for all traits in stress environment. Parents Jeuti and TS46 along with the crosses B9 x Jeuti, YSH401 x TS46, NRCYS05-03 x Jeuti and NRCYS05-03 x TS46 were found promising based on mean performance for yield attributing characters under stress condition. YSH401 was a good general combiner for heat susceptibility index and B9 x YSH401, B9 x TS46 and YSH401 x Jeuti were observed as heat tolerant. Main shoot length, number of flowers on main shoot, number of siliquae on main shoot, siliqua density, percent flower drop, number of siliquae on terminal shoot, biological yield per plant and seed yield per plant showed high genetic variation with high heritability and genetic advance. Number of flowers on main shoot was positively correlated with siliquae on main shoot and seed yield per plant.

Genetic variability predicting breeding potential of upland cotton (Gossypium hirsutum L.) for high temperature tolerance

BackgroundHigh temperature stress at peak flowering stage of cotton is a major hindrance for crop potential. This study aimed to increase genetic divergence regarding heat tolerance in newly developed cultivars and hybrids. Fifty cotton genotypes and 40 F1 (hybrids) were tested under field conditions following the treatments, viz., high temperature stress and control at peak flowering stage in August and October under April and June sowing, respectively.ResultsThe mean squares revealed significant differences among genotypes, treatments, genotype × treatment for relative cell injury, chlorophyll contents, canopy temperature, boll retention and seed cotton yield per plant. The genetic diversity among 50 genotypes was analyzed through cluster analysis and heat susceptibility index (HSI). The heat tolerant genotypes including FH-Noor, NIAB-545, FH-466, FH-Lalazar, FH-458, NIAB-878, IR-NIBGE-8, Weal-AG-Shahkar, and heat sensitive, i.e., CIM-602, Silky-3, FH-326, SLH-12 and FH-442 were hybridized in line × tester fashion to produce F1 populations. The breeding materials’ populations (40 F1) revealed higher specific combining ability variances along with dominance variances, decided the non-additive type gene action for all the traits. The best general combining ability effects for most of the traits were displayed by the lines, i.e., FH-Lalazar, NIAB-878 along with testers FH-326 and Silky-3. Specific combining ability effects and better-parent heterosis were showed by the crosses, viz., FH-Lalazar × Silky-3, FH-Lalazar × FH-326, NIAB-878 × Silky-3, and NIAB-878 × FH-326 for seed cotton yield and yield contributing traits under high temperature stress.ConclusionHeterosis breeding should be carried out in the presence of non-additive type gene action for all the studied traits. The best combiner parents with better-parent heterosis may be used in crossing program to develop high yielding cultivars, and hybrids for high temperature stress tolerance.

Delineating the role of plant stature towards heat stress tolerance in field pea (Pisum sativum L.)

Terminal heat stress severely affects field pea production in tropical climates. Identifying and characterizing marker-trait(s) remain vital for breeding heat-tolerant cultivars of field pea. Field pea genotypes are highly variable for plant stature; however, the significance of plant stature for yield stability under high-temperature conditions is not yet well understood. The study aimed to investigate the sensitivity and significance of plant stature toward yield sustainability of field pea under high-temperature environments. A panel of 150 diverse genotypes with variable plant statures [dwarf (<50 cm), semi-dwarf (50–80 cm), medium-tall (80–150 cm)] were grown under late sowing-induced high-temperature environments for two consecutive years (2017–2019). During the first year of the experiment, the late sown crops (15 and 30 days) were exposed to high-temperatures at flowering (+3.5 to +8.1 °C) and grain-filling (+3.3 to +6.1 °C) over timely sown crops. Likewise, elevated temperature during flowering (+3.7 to +5.2 °C) and grain filling (+5.4 to +9.9 °C) were recorded in late-sown environments (delayed by 27 and 54 days) in the next year. Medium-tall genotypes had longer grain-filling duration (7–10%), higher pod-bearing nodes (8–18%) and yield (22–55%), and lower yield losses (13–18%) over semi-dwarf and dwarf genotypes under high-temperature environments. Significant associations of plant height with yield, yield loss, and heat-susceptibility index in high-temperature environments suggested higher heat tolerance capacity of tall-type plants compared to dwarf and semi-dwarf types. GGEbiplot analysis revealed that the heat-tolerant genotypes were all medium tall-type (mean = 108 cm), while the heat-susceptible genotypes were mostly dwarf in stature. Hence, tall-type genotypes had better adaptability to high-temperature environments. Henceforth, the breeding approach for high-temperature tolerance in field pea may be designed by embracing tall-type backgrounds over dwarf plant to develop climate resilient cultivars.

Pollen viability-based heat susceptibility index (HSIpv): A useful selection criterion for heat-tolerant genotypes in wheat.

Terminal heat stress during reproductive stage in wheat (Triticum aestivum L.) causes pollen grain sterility and has a drastic impact on wheat crop production. Finding genotypes with high pollen viability under heat stress is crucial to cope with the impact of climate change through developing heat-tolerant cultivars. To assess the effect of terminal heat stress on pollen viability in a panel of spring wheat genotypes (N = 200), RCBD (randomized complete block design) field trials were conducted under normal and heat stress conditions for two consecutive years (2020-2021 and 2021-2022). Analysis of variance showed significant variation in genotypes, treatments, and genotype×treatment interaction. Fifty and 46 genotypes were categorized as heat tolerant (HSI pv < 0.5) in the first and second year, respectively. Twelve genotypes, namely, Chenab-70, Pari-73, Pak-81, MH-21, Punjab-76, NIFA-Aman, NUWYT-63, Swabi-1, Nisnan-21, Frontana, Amin-2000, and Pirsabak-2004, were found to be heat tolerant across the years. The violin plot displayed a trend of improvement in heat tolerance (HSI pv < 0.5) over the period of time in many modern wheat varieties. However, some modern wheat varieties released after 2001 such as Janbaz-09 (57%), Ghazi-2019 (57%), and Sindhu-16 (43%) had very low pollen viability under heat stress conditions. The results of phenotypic coefficient of variance (PCV%), genotypic coefficient of variance (GCV%), broad sense heritability (h2 bs), and genetic advance (GA) suggested the major contribution of genetic factors in controlling pollen viability trait. Higher values of h2 bs and GA under heat stress conditions suggested pollen viability as a heat tolerance trait controlled by additive genetic effects. Taken together, these results suggested pollen viability as a useful trait for selection in early generations under elevated temperatures. The genotypes identified as heat tolerant in both years can be used as genetic resources for breeding cultivars with higher pollen viability under elevated temperature conditions.

Application of Stress Indices to Identify Terminal Heat Tolerance Genotype in Field Pea (Pisum sativum var. arvense)

Background: The exposure of field pea crop to high-temperature stress during the anthesis and pod development stage led to poor pollination, development of shriveled pods and poor performance that results in reduced seed yield. The study aims to screen and identify heat-tolerant genotypes based on stress tolerance indices. One hundred forty-three field pea genotypes, including three checks evaluated in augmented block design for seed yield per plant under normal and late sown conditions to identify terminal heat-tolerant genotypes of field pea. Methods: Stress indices were computed based on seed yield per plant under normal (Yp) and late (Ys) sown conditions. The stress indices for seed yield are calculated as per the suggested method i.e. tolerance index (Hossain et al., 1990), heat susceptibility index (Fischer and Maurer, 1978), yield stability index (Bouslama and Schapaugh, 1984), mean productivity (Hossain et al., 1990), geometric mean productivity (Fernandez, 1992), stress tolerance index (Fernandez, 1992). Correlation coefficient and principal component analysis were done by using R (version 4.1.1) statistical software. Result: Correlation coefficient analysis reveals that seed yield under stress conditions was positively correlated with the indices viz., MP, GMP, STI and YSI whereas, it was negatively correlated with HSI, signifying that higher estimates of MP, GMP, STI and YSI and lower of HSI correspond to heat tolerance. The seed yield under both environments had a positive and significant association with MP, GMP and STI. Genotypes viz., EC-341743, P-1679, P-1384-3, P-179 and P-781 were found with high indices scores and showing their suitability for the breeding program for heat tolerance. The first two principal components (PCs) accounted for 97.46% of the total variation present in the genotype.

Utilization of Heat Susceptibility Index for Comparative Evaluation of Consistent Yield Performance in Wheat Under Heat Stress

Utilization of Heat Susceptibility Index for Comparative Evaluation of Consistent Yield Performance in Wheat Under Heat Stress

Study on heat stress indices and their correlation with yield in Indian mustard genotypes under diverse conditions

Increasing temperatures are becoming a major challenge for agro-systems. Late mustard planting often results in overall growth reduction, poor metabolism, less productivity and yield due to heat stress at the terminal stage. A set of 45 genotypes comprising introgression lines, landraces, wild species, induced mutants, advance breeding lines and the released varieties/cultivars were evaluated under normal (Yp) and stressed environment (Ys) for yield stability during 2016-2018. The higher value of heat tolerance index, geometric mean productivity, yield stability index, relative stability index and yield production score index with lower heat susceptibility index indicated tolerance to high temperature in some genotypes. Based on the yield performance and derived traits, six genotypes namely, HLM-41-13-2 and ELM-38 with zero erucic acid quality, MCN-05-8 an induced mutant, germplasm lines PCR-3 and CSR-1163, while MCN-08-2 is released variety RB50 were rated as promising for heat stress tolerance at both the locations. Biplot analysis indicated that genotypes under group I and IV are tolerant of high yield potential and stability in a stressed environment irrespective of location.

Documentation of Parents and Hybrids Tolerant to Terminal Heat Stress in Brassica juncea L.

Background: Fluctuations in temperature during the growth period can damage the inter-molecular interactions needed for proper growth, thus impairing plant development and fruit set, which leads to significant yield loss with greater risks for future global food availability, food accessibility, food utilization and food systems stability. Keeping these in mind present investigation was done to identify of parents and hybrids for terminal heat tolerance. Methods: Nine lines and three testers were crossed in line × tester fashion to develop hybrids. F1s were evaluated under timely and late sown conditions to study the effect of terminal heat stress by calculating, heat susceptibility index (HSI), heat tolerance efficiency (HTE) and stress tolerance index (STI) on yield and yield traits and to characterize parents and crosses on the basis of their relative tolerance against heat stress at the Agriculture Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi during Rabi 2017-18 and 2018-19. Result: Observations were made for different yield and yield related traits. Genotypes such as BPR 541-4 was found to be tolerant to heat stress at terminal stage and crosses such as Vardan × PM 30, Kranti × RH 406 and Kranti × Urvashi were found to be tolerant to heat stress for seed yield per plant at terminal stage during 2017-18 and 2018-19. Genotypes and crosses that were found to have minimum reduction in seed yield manifested tolerance to heat stress in terminal stage (had lowest HSI, Highest HTE and Highest STI).