Document Type : Original Article
Authors
1 PhD Student of Plant Breeding, Department of Plant Production and Genetics, Faculty of Agricultural Sciences and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
2 Professor, Department of Plant Production and Genetics, Faculty of Agricultural Sciences and Natural Resources University of Mohaghegh Ardabili, Ardabil, Iran
3 Assistant Professor, Crop and Horticultural Science Research Department, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Darab, Iran
Abstract
Introduction
Temperature is a major abiotic factor for regulating both growth and development of crop. But heat stress due to high ambient temperature is a serious threat to crop production worldwide. Heat stress is one of the major challenges in barley cultivation because it coincides with the flowering period and limits the crop productivity.
Materials and methods
To identify heat-tolerant genotypes, 17 promising genotypes of hull-less barley with three check genotypes were evaluated at the Darab Agricultural Research Station. The evaluation was conducted in a randomized complete block design with three replications at cropping year (2022-2023), under conditions non-stress and heat stress. The studied genotypes were planted in six lines along 6 m at a distance of 15 cm from each other. Seed consumption was determined by 400 seeds per square meter and thousand kernel weight for each genotype. Seeds were sown using an experimental plot planter (Wintersteiger, Ried, Austria). The fertilizer composition was 150 kg ha-1 nitrogen (twice), and di-ammonium phosphate and potassium sulfate were 100 and 50 kg ha-1, respectively (before planting). After the removal of perimeter plants, all experimental plots were harvested with an experimental grain harvester (Wintersteiger, Ried, Austria). The indices of stress tolerance studied were Yp: yield under non-stress condition; Ys: yield under stress condition; TOL: tolerance index; SSI: stress susceptibility index; MP: mean productivity; GMP: geometric mean productivity; STI: stress tolerance index; HM: harmonic mean; YI: yield index; YSI: yield stability index; RSI: relative stress index. Indices of FAI-BLUP (Factor analysis and ideotype-design), SIIG (selection index of ideal genotype), CSI (combination of significant indices) and MGIDI (multi-trait genotype-ideotype distance index) were used in order to integrate different indices of heat tolerance and better selection of genotypes in terms of heat tolerance.
Results and discussion
The results of the variance analysis for grain yield indicate a significant difference among genotypes at a 1% probability level in both heat stress and non-stress conditions. Heat stress led to a 24.8% decrease in grain yield in the examined genotypes. The results showed that based on the MP, GMP, HM and STI indices, genotypes 10, 16, 9 and 11 with the highest values of these indices were stress tolerant genotypes. Genotypes 6, 5, 3 and 18 with the highest values of RSI and YSI, respectively, were among the best genotypes. Based on the YI index, genotypes 10, 16, 5 and 6 with the highest YI value were introduced as stress-tolerant genotypes. The results of TOL and SSI indices showed that genotypes 6, 5 and 3 with the lowest values of these indices were tolerant genotypes. Positive and significant correlations were observed between the SIIG, FAI-BLUP, and CSI indices with Yp and Ys, while the MGIDI index showed negative significant correlations with Yp and Ys. The principal component analysis, capturing 99.8% of the variance in the relationships between the indices, grouped stress tolerance indices into three categories and genotypes into four groups. Genotypes 10, 16, and 9, with the highest values of SIIG, FAI-BLUP, and CSI indices and the lowest MGIDI values, were classified as heat tolerant genotypes.
Conclusions
In total, the results showed that by selecting indicators that have a significant correlation with grain yield in both stressed and non-stressed conditions and integrating them using combined indicators, the efficiency of selection increases. On the other hand, the results of FAI-BLUP, SIIG, MGIDI and CSI combined indices were completely similar in selecting the best genotypes and did not have any superiority over each other. Also, based on the results of the combined indices, genotypes 10, 16 and 9 were the superior barley genotypes in terms of tolerance to heat stress at the end of the season.
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