نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
2 گروه زیست‌شناسی، دانشکده علوم، دانشگاه شهید چمران اهواز، اهواز، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: High temperature stress is a major environmental stress that limits crop growth, metabolism, and productivity worldwide. Humid tropical areas are thought to threaten primarily by high temperature stress during reproductive phase which causes a drastic change in physiological and biochemical behavior of the major crops under future climates. Canola (Brassica napus L.) is an oilseed crop cultivated for purposes relating to household consumption and industry. Delay in sowing date are known to accelerate the crop development and shorten the growing period and distance of the plant from suitable growing conditions. Salicylic acid (SA), as a plant growth regulator, plays a major role in plant growth and development and promote photosynthesis under heat stress by influencing various biochemical reactions and physiological processes. SA in known to alleviate adverse effects of heat stress on crop production through changes in photosynthesis traits and enzymatic antioxidant activities. The aim of this study was to evaluate the effect of SA foliar on the yield, photosynthetic characteristics, and enzymatic antioxidant activities of canola cultivars under terminal heat stress caused by late autumn winter sowing dates in Ahvaz conditions.
Materials and Methods: In order to investigate the effect of SA foliar application on the yield, photosynthetic characteristics, and enzymatic antioxidant activities of canola cultivars in two sowing dates, a field experiment carried out in a split plot factorial in randomized complete block design with three replicates per treatment at the research farm of Shahid Chamran University of Ahvaz in 2023-2024 growing season. Main plots consisted of two sowing dates; November 11, and December 11 (Normal and late sowing dates, respectively), and sub plot consisted of factorial arrangement of different concentrations of SA (0, and 200 μm l-1, SA), and canola cultivars (Hyola4815, Agamax, Hyola50, and Trapper). SA treatments were implemented at stem elongation (32) and inflorescence emergence (53).
Results: Results showed that the interaction between sowing date, hormone foliar application, and cultivars significantly affected most of the traits. Heat stress in late sowing date led to a significant reduction in seed (28%) and oil yield (35%), chlorophyll index (11%), stomatal conductance (36%), but increased catalase (26%), peroxidase (32%), ascorbate peroxidase (76%), superoxide dismutase (79%), glutathione reductase (80%) enzyme activities and hydrogen peroxide (335%) and malondialdehyde (MDA) concentration (33%) compared to normal sowing date. A significant difference was found among cultivars in terms of all traits. The concentration of 200 μm l-1 SA improved the studied traits in both sowing dates. In late sowing date, foliar application of salicylic acid enhanced stomatal conductance (15%), chlorophyll index (2%), seed (23%) and oil yield (31%), catalase (16%), peroxidase (11%), ascorbate peroxidase (8%), superoxide dismutase (10%), glutathione reductase (12%) enzyme activities, but decreased hydrogen peroxide (5%) and MDA (21%), when compared to salicylic acid -deficient plants, According to these results, Agamex and Trapper cultivars perform better than other cultivars and largely maintain their high yield through improvement of the mentioned traits under heat stress conditions caused by late sowing time.
Conclusion: The adverse effects of heat stress were mitigated by the application of SA as a foliar spray. SA treatment played a crucial role in maintaining gas exchange, promoting the production of enzymatic antioxidants and reducing hydrogen peroxide and MDA concentrations. These findings provide evidence that exogenous SA (200 μm l-1) can be an effective strategy in improvement of seed and oil yield of canola cultivars under late autumn sowing date conditions in tropical regions such as Khuzestan.
کلیدواژه‌ها [English]
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