نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری، گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
2 استاد، گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
3 دانشیار، گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
In arid and semi-arid regions, drought stress particularly during the reproductive and late-season stages, often accompanied by high temperatures substantially reduces wheat yield. The use of early-maturing cultivars with shortened growth cycles, which complete development prior to the onset of stress, represents an effective strategy to mitigate these adverse effects. Evaluating the response of these cultivars to irrigation cutt-off during reproductive stages facilitates the identification of drought-tolerant genotypes. This study aimed to investigate the effects of drought stress on morphological, phenological, and functional traits of early-maturing near-isogenic wheat lines subjected to irrigation cutt-off during reproductive growth.
Materials and methods
The experiment was carried out in split-plot based on a randomized complete block design with three replications at the research field of Shahid Chamran University of Ahvaz, Ahvaz, Khuzestan province, Iran, in 2024-2025 growing season. Irrigation treatments at three levels, including full irrigation (control), irrigation cut-off from the beginning of flowering to early dough stage (code 61-83 in BBCH scale) and irrigation cut-off from early dough stage to full grain maturity (code 83-92 in BBCH scale) was considered as main factor, and five bread wheat cultivars and near-isogenic lines, including Roshan, Mahdavi, Roshan’s near-isogenic line, Mahdavi’s near-isogenic line and Mehregan cultivar (control) as sub-factor. The measured traits included phenological traits (number of days to heading and days to maturity), morphological traits (plant height and peduncle length), yield components (spike weight, number of grains per main spike, spike weight and 1000-grain weight), as well as biological yield and harvest index which were measured at full maturity. To group the studied genotypes and traits, cluster analysis method was used and the respective dendrogram was drawn as a heat map using R-studio ver. 2023 software. Data analysis of variance was conducted using SAS ver. 9.1 software and comparison of means was performed using Duncan’s multiple range test at 5% probability level.
Research findings
The results of this study indicated that there was a significant difference between cultivars and near-isogenic lines for most of the evaluated traits. Irrigation cut-off at different growth stages significantly reduced the number and weight of grains per spike, 1000-grain weight, and days to maturity, ultimately leading to decreased grain yield across all cultivars and near-isogenic lines. However, greater reductions were obsberved in the cultivars compared with their corresponding near-isogenic lines. Under irrigation cut-off applied at the flowering stage, the grain yield of Roshan and it’s near-isogenic line, Mahdavi and it’s near-isogenic line, and Mehregan decreased by 33%, 38%, 29%, 29% and 20%, respectively, compared with full irrigation treatment. Corresponding reductions under irrigation cut-off treatment at the grain-filling stage were 12%, 15%, 15%, 15% and 8%, respectively. Grain yield in the Mahdavi cultivar and it’s near-isogenic line, as well as in Mehregan cultivar, was significantly higher than that of the Roshan cultivar and it’s near-isogenic line under all irrigation cut-off treatments. Across all irrigation cut-off treatments, the number of days from seed sowing to maturity in near-isogenic lines of Roshan and Mahdavi was 10 to 15 days fewer than their parental cultivars. This earliness likely contributed to reduced exposure to drought stress during critical reproductive stages, enhancing yield stability. Furthermore, irrigation cut-off during reproductive growth stages further truncated the reproductive cycle of both cultivars and near-isogenic lines by approximately three to five days compared with the full irrigation treatment.
Conclusion
Overall, the findings of this study showed that the the near-isogenic lines outperformed their parent cultivars in terms of yield and other agronomic traits. The near-isogenic line of Mahdavi, by employing an earliness strategy and shortening the time to flowering and maturity, achieved the highest grain yield under both full irrigation and cut-off irrigation treatments. Therefore, similar to the Mehregan cultivar, it is recommended for cultivation under mild water stress conditions in the Khuzestan region.
کلیدواژهها [English]
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