Document Type : Research Paper
Authors
1
M. Sc. Student, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
2
Associate Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3
Assistant Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
4
Associate Professor, Department of Agronomy and Plant Breeding, Shahid Bahonar University of Kerman, Kerman, Iran
10.22124/cr.2024.26382.1804
Abstract
Introduction
Heat stress is a growing threat to food security and agricultural production. Terminal heat stress is a major abiotic stress especially in tropical and sub-tropical regions dramatically affecting crop growth and yield. Therefore, developing early-heading bread wheat cultivars is an appropriate method for many grain-producing regions experiencing terminal heat stress. In this experiment, the effect of terminal heat stress was assessed on morpho-phenological and yield traits of bread wheat cultivars and near-isogenic lines.
Materials and methods
The experiment was carried out in split-plots arrangement based on randomized complete block design with three replications in Shahid Chamran University of Ahvaz, Iran, in 2022-2023. The main plots consisted of two sowing dates; November 23 and January 23 (Normal and late sowing dates, respectively), and the sub-plots consisted of bread wheat cultivars and Near-isogenic lines (Roshan, Kalheydari, Mahdavi, Near-isogenic line of Roshan, Near-isogenic line of Kalheydari and Near-isogenic line of Mahdavi and Mehrgan). Sowing date with desired temperature was considered as control, and late sowing date was considered as heat stress to ensure heat stress coincided with flowering and grain-filling phases. Combined analysis of variance was performed.
Research findings
There was a significant difference between cultivars and isogenic lines in terms of most traits. Heat stress induced by late sowing caused a significant decrease in grain yield of cultivars and Near-isogenic lines through a significant reduction in spike weight, grain number per spike, grain weight per spike and 1000-grain weight. Higher reductions were observed in cultivars compared with their Near-isogenic lines. The grain yield of the cultivars and Near-isogenic lines; Roshan, Near-isogenic line of Roshan, Kalheydari, Near-isogenic line of Kalheydari, Mahdavi, Near-isogenic line of Mahdavi and Mehrgan significantly decreased under heat stress by 36, 35, 31, 31, 35, 32 and 30%, respectively, when compared to the control. The reductions in cultivars were almost similar to their Near-isogenic lines, but Near-isogenic line of Roshan and Roshan and Mehrgan cultivars showed the highest grain yield in both sowing dates. In Near-isogenic lines of Roshan, Kalheydari and Mahdavi, reducing the number of days from sowing to heading (9,9,17 days, respectively) and the days from sowing to full maturity (6,6,11 days, respectively), as two main components of earliness, caused to minimize exposure to terminal heat stress during the flowering and grain filling phases with higher grain yield and stability.
Conclusion
Overall, the results of this study showed that the near-isogenic line of Mahdavi through the earliness strategy and shortening the time for flowering and maturity had the highest grain yield and stability, and recommended for late sowing date in Khuzestan conditions.
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