Terminal Heat Stress Conditions Research Articles

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.

Unlocking genetic insights: Evaluating wheat RILs for physiobiochemical traits under terminal heat stress conditions

BackgroundThe increasing impacts of heat stress on wheat production due to climate change has entailed the development of heat-resilient crop varieties. To address this, two hundred recombinant inbred lines (RILs) derived from a cross between WH711/WH1021 were evaluated in a randomized block design (RBD) with two replications at CCSHAU, Hisar, during 2018-19 under heat stress and non-stress conditions. Heat stress was induced by altering the date of sowing so that the grain filling stage coincide with heat stress.ResultsHeat stress adversely affects RILs performance, as illustrated by alterations in phenotypic traits. Highest coefficients of variations were recorded for TAA, CTD 1, WUE, CTD 2, Cc and A under non-stress and heat stress conditions whereas gs, WUEi and GY under non-stress and SPAD 1, SPAD 2, GY and NDVI 2 under heat-stress conditions recorded moderate estimates of coefficient of variations. CTD 2, TAA, E, WUE and A displayed a significant occurrence of both high heritability and substantial genetic advance under non-stress. Similarly, CTD 2, NDVI 2, A, WUEi, SPAD 2, gs, E, Ci, MDA and WUE exhibited high heritability with high genetic advance under heat-stress conditions.ConclusionsComplementary and duplicate types of interactions with number of controlling genes were observed for different parameters depending on the traits and environments. RILs 41, 42, 59, 74, 75, 180 and 194 were categorized as heat tolerant RILs. Selection preferably for NDVI 1, RWC, TAA, A, E and WUEi to accumulate heat tolerance favorable alleles in the selected RILs is suggested for development of heat resilient genotypes for sustainable crop improvement. The results showed that traits such as such as NDVI, RWC, TAA, A, E, and WUEi, can be effective for developing heat-resilient wheat genotypes and ensuring sustainable crop improvement.

Efficacy of Various Chemical Sprays on Plant Growth of Chickpea (Cicer arietinum L.) in Terminal Heat Stress Conditions

Heat stress is now widely accepted as an important ecological factor influencing growth of plants and production. Rising temperatures as a result of global warming cause heat stress, reducing plant development and potential output throughout the entire globe. A field experiment was carried out at Chandra Shekhar Azad University of Agriculture & Technology, Kanpur, to minimize the heat stress induced-losses in chickpea plants with the foliar spray of chemicals during two consecutive years 2021-22 and 2022-23 at Rabi season (November-April). Experimental treatments comprise two chickpea varieties (RVG-202 and RVG-203) sown on same day (15th November). foliar spray of seven chemicals at at vegetative, anthesis and at both stages. The chemcials include Salicylic acid @ 800 ppm, Salicylic acid @ 400 ppm, Ascorbic acid @ 10 ppm, Potassium chloride @ 1%, Thiourea @ 400 ppm, Cycocel @ 400 ppm and Control (no spray). Results suggested that heat stress severely reduced the chickpea growth and productivity. However, foliar application of salicylic acid and thiourea positively affected the plant growth attributes which ultimately increased the final productivity. Concisely, the foliar spray of chemicals particularly, salicylic acid and thiourea modulated the heat stress induced losses in chickpea cultivars, RVG-202 and RVG-203 by improving their antioxidant defense mechanism and enhanced the productivity.

Genetic variability and stability of Desi chickpea (Cicer arietinum L.) genotypes under late sown terminal heat stress conditions

Genetic variability and stability of Desi chickpea (Cicer arietinum L.) genotypes under late sown terminal heat stress conditions

Evaluation of Indian Durum Wheat Genotypes for Yield and Quality Traits Using Additive Main-Effects and Multiplicative Interaction (AMMI) Biplot Analysis under Terminal Heat Stress Conditions

Evaluation of Indian Durum Wheat Genotypes for Yield and Quality Traits Using Additive Main-Effects and Multiplicative Interaction (AMMI) Biplot Analysis under Terminal Heat Stress Conditions

Characterization of wheat genotypes for terminal heat stress tolerance in Bangladesh

This study was aimed to determine the types and levels of variability, heritability, genetic progress, relationships between yield and the features that contribute to it, and some key indicators of terminal heat stress tolerance. Twenty different wheat genotypes were planted in the fields over the course of six different treatments spaced 10 days interval following a Randomized Complete Block Design (RCBD) with three replications. A high degree of significant variation was observed for all the characters studied. Estimates of the genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) revealed that the phenotypic coefficient of variation was higher than the genotypic coefficient of variation, which indicates a large effect of environment on the expression of the characters studied. The highest estimates of PCV and GCV were observed for grain yield/plant followed by the number of tillers/plant. Heritability estimates revealed that characters like pollen fertility and sterility exhibited the highest heritability followed by days to maturity. The genetic advance was higher for grains/plants followed by plant height. Grain yield showed significant and positive phenotypic and genotypic correlations with grains/plant and 100-grain weight. Phenotypic path analysis revealed a significant direct positive effect of 100-grain weight on grain yield. Principal component analysis (PCA) revealed that the first five components having greater than one Eigenvalue contributed to 83.41% variability. The heat stress tolerance indices revealed that Bijoy and BARI Gom-25 had the lowest tolerance index (TOL), stress susceptibility index (SSI) values and highest yield susceptibility index (YSI) values which show more tolerance and less susceptibility to terminal heat stress and produce moderate grain yield under terminal heat stress. Balaka and Shughat had the highest mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI) values and produce high yields under terminal heat stress conditions.

HI 1634 (PusaAhilya), high yielding bread wheat variety tolerant to terminal heat stress conditions of Central Zone

HI 1634 (Pusa Ahilya), a high yielding bread wheat variety with an average yield of 51.6 q/ha was released by Central Sub-Committee on Crop Standards, Notification and Release of Varieties for Agricultural Crops, Government of India vide notification No. S.O. 500 E dated 29.01.2021 for commercial cultivation under late sown irrigated conditions of central wheat growing zone of India. HI 1634 performed superior when grown under various sowing conditions with seedling and adult plant resistance to all pathotypes of stem and leaf rusts which are virulent in India and postulated to have stem rust gene Sr31. HI 1634 had an excellent chapati quality and bread making quality along with good levels of essential micronutrients like iron and zinc content. HI 1634 will be a high yielding and terminal heat tolerant bread wheat variety ensuring better market price for farmers and will be a new option for the millers and baking industries.Â

Genetic stability analysis of bread wheat hybrids and parents under semi-arid eastern plains of Rajasthan

Aim: The study aimed to evaluate ten wheat cultivars along with 45 F1 under different environments to identify best suited environment for potential expression of grain yield and related traits under terminal heat stress. Methodology: Ten wheat cultivars and 45 F1 were evaluated under three different environments at Rajasthan Agricultural Research Institute, Durgapura, Jaipur (SKNAU, Jobner). The experiment was carried out in randomized block design with 3 replications and each plot had 2 rows for F1 and 4 rows for parents with 30×10 cm spacing. The parents of the crosses were selected on basis of their superiority in performance across diverse ecologies. Results: The results of present investigation revealed that first two principal components contributed to nearly 63 % of total variance that is grouped in two clusters. Genotype plus genotype by environment interaction view revealed top cultivars and hybrids under terminal heat stress conditions. AMMI biplot analysis indicated environment 1 and environment 2 as the best suited environments for potential expression of grain yield and related traits. The study identified potential donors, cultivars C306, Raj4079, Raj1482 and PBW396 for earliness and cultivarsCR43, CR20 and PBW590 for grain yield and related traits under terminal heat stress conditions. Interpretation: The grain yield can be improved by selecting for higher grain number, biomass and harvest index as revealed from their positive correlations. The presence of G×E interaction provides the opportunity to select for the stable genotypes for diverse ecologies. On other hand, environment specific genotypes can be targeted in befitting ecologies. AMMI and GGE biplot based stability analysis prove to be an efficient approach in testing the genotypes performance in multi-environment trials for selection of stable heat resilient cultivars. Key words: Genetic stability, Hybrids, Terminal heat stress, Wheat

Wheat Varietal Response to Relative SPAD Index (RSI) and Relative Normalized Difference Vegetation Index (RNDVI) under Variable Nitrogen Application and Terminal Heat Stress along with Yield Repercussion

Nitrogen (N) deficiency and heat stress (HS) are major abiotic stresses that affect the quantity and quality of wheat grains. This study was conducted to examine wheat varietal response to RSI and RNDVI at the anthesis stage and their relationship to yield and yield-related traits under variable N supply and terminal heat stress. Twelve wheat varieties were evaluated in 2016–2017 and 2017–2018 at the National Agricultural Research Centre (NARC), Islamabad, Pakistan. The experiment was divided into three sets, i.e., N120 (120 kg N/ha), N60 (60 kg N/ha) and N0 (0 kg N/ha), based on the nitrogen fertilizer application. The physiological and yield-related parameters were recorded. Mean grain yield for all twelve varieties, averaged from two years of data, ranged between 1655.0 and 3890.1 kg/ha. Maximum RSI (0.99), RNDVI (1.03) and GY (3890.9 kg/ha) were recorded for FSD-08, while AARI-11 showed minimum RSI (0.50), RNDVI (0.56) and GY (1396.40 kg/ha). In the present study, mean CTD was lower, at N0 (3.57 °C), followed by N60 (5.07 °C) and N120 (5.47 °C) on average for the two years of data. The strong positive correlation of RSI and RNDVI with grain yield at R2 = 0.73 and R2 = 0.49 suggest that these parameters can be used as efficient and precise selection criteria for identifying nitrogen-use-efficient wheat varieties under terminal heat-stress conditions. This work will help the researchers to identify and develop nitrogen-use-efficient and thermos-tolerant wheat cultivars by minimizing the negative impacts of heat stress at the anthesis stage.

Genotype by environment interaction and association of yield contributing traits in sunflower genotypes under the environmental condition of Sargodha, Pakistan

Abstract Oil content and other yield contributing metric traits are highly influenced by environmental conditions hence, the phenotype of a trait is a response of interaction between environment and genetic makeup of crop. Climate change is one of the major challenge faced by growers nowadays because it adversely affects the growth and development of sunflower and ultimately reduce oil content. Therefore, keeping in view the challenge of climate change, the present research was conducted during 2019, to evaluate the performance of 28 sunflower hybrids under normal and terminal heat stress conditions at the research farms of the College of Agriculture, University of Sargodha, Sargodha-Pakistan. Pakistan. Data were recorded on days to 100% flowering, stem girth (cm), head diameter (cm), 100-achene weight (g) and oil contents (%). Analysis of variance revealed the presence of genetic diversity among 28 hybrids for all the traits under consideration. Irrespective of traits, the mean square revealed the role of experimental error was minimum than the environment, genotype and their interaction (G × E). The environmental influence was found to be 68.94, 49.99, 53.94% for days to 100% flowering, stem girth (cm) and 100-achene weight (g), respectively. However, genotypes play a major source of variation for head diameter (cm) and oil content (%). Oil content has a significant positive correlation with traits under study. Based on mean performance under normal and terminal heat stress conditions hybrid SF-19033 and SF-19028 performed best for yield contributing traits and adoptable under the environmental conditions of Sargodha-Pakistan.

Evaluation of some bread wheat genotypes for heat tolerance under terminal heat stress conditions

Terminal heat stress leads to significant yield reduction in wheat. Thus, the determination of heat tolerant genotypes is of major importance in wheat breeding program. The present study was conducted at Shandaweel agricultural research station, Sohag, Egypt during 2019/2020 and 2020/2021 growing seasons, to evaluate twelve bread wheat genotypes under normal sowing (20 November) and late sowing (30 December) dates, the experiment set up as a randomized complete block design with three replications. Results revealed that late sowing (terminal heat stress) had a significant adverse impact on agronomic, physiological traits and grain carbohydrate content. The genotype Shandaweel 2, followed by Giza 171 and Sids 14 performed better than other genotypes for grain yield under the normal sowing. On the other side, Shandaweel 2 outperformed the tested genotypes under the late sowing. Based on heat susceptibility index (HSI), the cultivars Sids 12, Misr 2, Sakha 95 and genotype Shandaweel 2 showed HSI<1 and they can be labeled as heat tolerant genotypes, while Sids 14, Misr 1, Giza 171 and Misr 3 showed HSI>1 and they can be considered as heat sensitive cultivars. GGE biplot analysis and ranking of genotypes revealed that the new line Shandaweel 2 was the an ideal genotype in terms of yielding ability and stability and it was suitable for planting under normal and late sowing conditions, while Giza 171 was suitable for planting under the normal sowing. The GYT biplot and superiority index showed that Shandaweel 2 and Giza 171 had the best traits profile.

Interrelationships among different grain characteristics of wheat grown under optimum and late sowning date conditions in the Eastern Indo-Gangetic plains of India

Wheat growth has been severely affected by increases in global temperature. The Eastern Indo-Gangetic Plains of India face similar constraints due to the traditional wheat–rice cropping system where wheat planting is often delayed leading to high temperature induced terminal heat stress. Grain characters like grain length, width, area along with starch synthesis are affected severely during heat stress. Considering the importance of grain traits, we screened the response of 55 wheat genotypes under terminal heat stress conditions to ten grain characteristics. We found that the means of all the grain traits were reduced in heat stress conditions. The effect of heat stress shows a significantly reduced grain width and perimeter, but the extent of damage is less on different grain starch characteristics e.g., grain starch area (GSA), grain starch length (GSL) and grain starch volume (GSV). Stepwise multiple regression analysis revealed that grain starch area and grain volume are the best predictors of yield under optimum sowing date conditions whereas, grain width is the best predictor under late sowing date conditions. Interrelationship studies among ten grain characters showed that the genotypes with higher levels of grain starch characteristics (GSA, GSL and GSV) in combination with the five grain size characters (grain length, grain width, grain perimeter, grain area, A/B-type starch granules) under late sowing date conditions should be promoted for the cultivation of wheat in heat stress prone areas. The present study identified and recommends some heat tolerant wheat genotypes in terms of higher yield and grain starch characteristics namely, CRPW-33, CRPW-17, CRPW-12, CRPW-126 and CRPW-21.

Performance and Stability of some Bread Wheat Genotypes across Terminal Water and Heat Stresses Combinations Using Biplot Techniques

The current study was conducted at Shandaweel Agric. Res. Stat., Agric. Res. Center, Egypt. Eighteen bread wheat genotypes were grown under four treatments during 2018/19 and 2019/20 seasons. The treatments were (1) normal conditions (sowing on 25th November and 5 irrigations). (2) Terminal water stress conditions (sowing on 25th November and 3 irrigations). (3) Terminal heat stress conditions (sowing on 25th December and 4 irrigations). (4) Combined stresses (sowing on 25th December and 3 irrigations). The combined analysis of variance showed significant differences between the genotypes, treatment, seasons for all the studied traits. The mean performance of the genotypes showed that L11 was the highest grain yield and grain filling rate under normal, water stress, heat stress, combined stresses as well as overall treatments. Genotype by genotype-environment biplot (GGE biplot) illustrated that the best performing genotype under normal conditions was Baj 1 while Shandaweel 1 was the best performing genotype under stress combinations. Genotype x trait biplot (GT biplot) showed a positive correlation between all the traits except, days to heading and days to maturity. Genotype by yield*trait biplot (GY*T biplot) was constructed to estimate superiority and stability for the genotypes. GY*T biplot showed a positive correlation between all yield*trait combinations. Based on superiority index (SI), the best performing genotypes was L11 (SI = 1.830) and the worst was L7 (SI = 1.935). L11 genotype can be utilized in breeding program as a source for abiotic stresses tolerance or can be evaluated in preliminary yield trials at the national level.

Selection indices for enhanced selection efficiency in Indian mustard under terminal heat stress conditions

With global increase in temperature, terminal heat stress (THS) has emerged as a major challenge in food crops. Indian mustard (Brassica juncea L. Czern and Coss), C3 plant, grows well at 15-20°C. Heat stress at seedling as well as at flowering stage leads to enhanced vegetative growth and flower abortion leading to loss in seed yield. Late sowing after cotton and rice harvest expose the crop to high temperature stress during reproductive stage of development. A fixed diversity stock of 486 Indian mustard lines were evaluated under delayed planting conditions to expose the crop to THS for two consecutive years. Selection indices were computed using four different combinations of traits via Kang_SAS Path computer program along with expected genetic advance (GA) at 5% selection intensity. Set1, comprised of five traits viz., plant height (PH), number of secondary branches (NSB), number of siliquae on main shoot (NSMS), seed yield (SY) and 1000-seed weight (TSW) were recorded the highest GA (8.612) in comparison to other trait combinations tested in present study. Other important finding was slight difference in GA of set I (8.612; SY included) and set II (8.599; SY excluded) with efficiency of selection index 131% and 130%, respectively. This recommended that in initial breeding generations (F2/F3), a breeder may base his selection on four yield related traits (PH, NSB, NSMS and TSW) only without significant loss in genetic gains. This will save resources and time of breeders to compute seed yield. This is the first report on computation of selection index for efficient simultaneous selection under THS in Indian mustard.

Effect of zinc sulfate application on grain yield of bread wheat (Triticum aestivum L.) cv. Chamran under terminal heat stress conditions in Ahvaz

Effect of zinc sulfate application on grain yield of bread wheat (Triticum aestivum L.) cv. Chamran under terminal heat stress conditions in Ahvaz

Genome wide association studies for yield and its component traits under terminal heat stress in Indian mustard (Brassica juncea L.)

Breeding for terminal heat stress (THS) in Brassica juncea L. Czern & Coss is recognized as an imperative objective for sustained productivity in contemporary climatic changes. A fixed diversity stock of 491 genotypes was documented for wide range of variations for seed yield under natural terminal heat stress. A set of top 20 genotypes comprising introgression lines from wild species Erucastrum cardaminoides and B. tournefortii; derived B. juncea lines using B. carinata and B. napus; land races;, commercial cultivars and breeding lines, having the lowest heat susceptibility index and the least yield reduction under heat stress, have been identified as potential heat tolerant donors. A panel of 96 genotypes was constituted from this stock on the basis of their differential response to heat susceptibility index and seed yield reduction under natural THS. The constituted panel was evaluated for validation under controlled conditions for ten seed yield-related traits. Moderate to low correlations between SY and its related traits were observed in NS and THS conditions. Double digest restriction site associated DNA sequencing of 71 genotypes identified 18,258 SNPs after filtration. Least square means of all the traits under NS and THS conditions and the best linear unbiased predictors along with identified SNPs were used for genome-wide association study. A total of 34 SNPs under NS, 24SNPs under THS and 30SNPs using BLUP values were found to be associated with all seed yield-related traits. Chromosome B05 harbored the maximum number of SNPs (nine) followed by chromosomes A07 and A09 (eight SNPs each). SNPs under NS conditions could not be associated with THS. This is the first report on the identification of 24 marker-traits associations detected for SY and its component traits under THS conditions. It may be possible to develop the molecular markers for significant SNPs after due validation. The constituted panel may also serve as a source of allelic diversity for genes controlling various economic traits. The derived introgression lines as potential heat tolerant donors indicated the possibility of using wild species to breed for abiotic stress tolerance in Indian mustard.

Mapping QTLs for physiological and biochemical traits related to grain yield under control and terminal heat stress conditions in bread wheat (Triticum aestivum L.).

In order to detect genomic regions with different effects for some of the physiological and biochemical traits of wheat, four experiments were conducted at Research Farm of Agricultural and Natural Resources Research Center of Zabol in 2015-2016 and 2016-2017 growing seasons. The experiments were carried out using four alpha lattice designs with two replications under non-stress and terminal heat stress conditions. Plant materials used in this study included 167 recombinant inbred lines and their parents ('SeriM82' and 'Babax'). Six traits including grain yield (GY), proline content (PRO), water soluble carbohydrates (WSC), maximum efficiency of photosystem II (Fv/Fm), cytoplasmic membrane stability (CMS) and chlorophyll content (CHL) were evaluated. Genetic linkage map consisted of 211 AFLP marker, 120 SSR marker and 144 DArT markers with 1864cm length and 4.4cm mean distance. QTL analysis was carried out using a mixed-model-based composite interval mapping (MCIM) method. By the combined analysis of normal phenotypic values, 27 additive QTLs and five pairs of epistatic effects were identified for studied traits, among which two additive and one epistatic QTL showed significant QTL × environment interactions. By the combined analysis of stress phenotypic values, a total of 26 QTLs with additive effects and 5 epistatic QTLs were detected, among which one additive and one epistatic QTL showed QTL × environment interactions. Six QTLs with major effects (QGY-2B, QGY-2D, QPro-5B, QWSC-4A, QFv/Fm-6A and QCMS-4B), which were common between two conditions could be useful for marker-assisted selection (MAS) in order to develop heat tolerant and high-performance wheat varieties.

Assessment of terminal heat tolerance ability of wheat genotypes based on physiological traits using multivariate analysis

Terminal heat stress is one of the limiting factors in wheat production and it is expected to rise under present scenario of climate change. The present study was conducted to evaluate the performance of 40 wheat genotypes under terminal heat stress conditions based on eight physiological traits. The plants were sown late (i.e. on 5th January) to expose them terminal heat stress. The genotypes were evaluated using multivariate analysis viz. Ward’s method of hierarchical clusters analysis, discriminant analysis and principle component analysis. The genotypes were categorized into three groups namely tolerant, intermediate and sensitive. Tolerant genotypes like DBW 14, RAJ 3765, HD 2643 and HALNA performed physiologically better in terms of higher membrane stability index (MSI), chlorophyll content, photosynthesis rate (Pn), harvest index under heat stress conditions. Genotypes HD 2987, SHANGHAI, HD 2402 and WH 730 were found to be heat sensitive. Physiological traits like MSI, SPAD value, Fv/Fm ratio and Pn were found to be most important contributor in grouping of genotypes and showed positive correlations (r) of 0.73, 0.47, 0.41 and 0.39 with grain yield, respectively, which is significant at p < 0.05. The large genetic diversity was found among the genotypes based on physiological traits. These genotypes can be utilized in wheat improvement programme for heat tolerance.

Effect of Different Nitrogen Levels and Cytokinin Foliar Application on Yield and Yield Components of Wheat at Terminal Heat Stress Conditions in Ahwaz

Effect of Different Nitrogen Levels and Cytokinin Foliar Application on Yield and Yield Components of Wheat at Terminal Heat Stress Conditions in Ahwaz

Canopy Temperature as a Selection Parameter for Grain Yield and Its Components in Durum Wheat Under Terminal Heat Stress in Late Sown Conditions

Relationship of canopy temperature (CT) with grain yield and its components were evaluated under terminal heat stress conditions, in Central India, during 2010–2013 growth season, in which 102 durum wheat genotypes were tested under late and very late sown conditions. The genotypes in late sown conditions showed higher grain yield/plant, biomass/plant, harvest index and test grain weight compared to very late sown conditions. The mean grain yield/plant and biomass yield/plant were 18.8 and 55.9 g, respectively, under late sown conditions, compared to 15.1 and 48.9 g under very late sown conditions. Genotypes MACS 3125, HI 8627, HI 8638, HI 8498, WH 896 and HI 8691 showed stable performance under both late and very late sown conditions over the years and hence exhibited high degree of tolerance to terminal heat. CT ranged from 21.0 to 24.7 and 20.2 to 24.9 °C under late and very late sown conditions, respectively. CT showed significant and negative correlation with grain yield/plant and biomass/plant under late and very late conditions and number of grains/spike and 1000 grain weight under very late sown conditions and hence can be successfully used as an important selection parameter in breeding programme at field. The study suggests that CT can be used as one of the important criteria for the selection of stable genotypes under late heat and very late heat stress conditions and can help in improving production and productivity of durum wheat under terminal heat stress conditions.