نوع مقاله : علمی - پژوهشی
نویسندگان
1 دانشجوی دکتری گروه جنگلداری دانشکده منابع طبیعی دانشگاه لرستان ملایر، ملایر، ایران
2 استاد، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه لرستان، لرستان، ایران
3 استادیار، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه لرستان، لرستان، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Over the past two decades, the severity of drought and the frequency of dust storms have increased markedly in Iran, particularly in the western and southwestern provinces, imposing substantial pressure on natural ecosystems. The Zagros forests, one of the country's most valuable and vulnerable forest ecosystems, are highly susceptible to the combined impacts of drought and dust deposition. These environmental stressors reduce tree growth, disrupt physiological processes, and accelerate forest decline. Wild pistachio (Pistacia atlantica Desf.), an ecologically and economically important tree species of Iran's arid and semi-arid regions, plays a crucial role in maintaining ecosystem stability. Therefore, this study aimed to investigate the combined effects of drought and dust stress on the antioxidant enzyme activities of wild pistachio seedlings in order to better understand their defense mechanisms and provide insights for improving their resilience to environmental stress.
Material and Methods: This study was conducted from March 2023 to December 2023 in the greenhouse of the Faculty of Agriculture and Natural Resources, Lorestan University. A factorial experiment was arranged as a split-plot design within a randomized complete block design using 384 wild pistachio seedlings. Drought stress was applied at three irrigation levels corresponding to 100% (control), 75%, and 50% of field capacity, while dust stress consisted of four concentrations: 0, 350, 750, and 1,500 μg m⁻³. Growth chambers with transparent plastic covers were constructed inside the greenhouse, and the seedlings were placed within these chambers. The potting medium consisted of equal proportions of agricultural soil, sand, and farmyard manure, similar to the substrate commonly used in forest nurseries. At the end of the experiment, leaf samples were collected and the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were determined under laboratory conditions.
Results: Drought and dust stresses significantly affected the activities of all antioxidant enzymes at the 1% probability level. However, the interaction between the two stressors was not significant for APX activity, indicating that each stress factor independently influenced this enzyme. Catalase activity increased markedly with increasing stress intensity. Under severe drought (50% of field capacity), APX and SOD activities showed a slight decline at the initial dust concentration (350 μg m⁻³), which may reflect temporary impairment of the antioxidant defense system under oxidative stress. With further increases in dust concentration to 750 and 1,500 μg m⁻³, SOD activity increased substantially, suggesting activation of compensatory defense mechanisms to counteract reactive oxygen species. Although POD activity was significantly influenced by both drought and dust stress, its response did not exhibit a consistent increasing or decreasing trend.
Conclusion: Wild pistachio seedlings responded to the combined effects of drought and dust stress by significantly enhancing the activities of CAT, POD, and SOD, demonstrating an effective antioxidant defense mechanism. The marked increase in SOD activity, as the first line of defense against reactive oxygen species, highlights its critical role in protecting cellular integrity and enhancing stress tolerance. Nevertheless, under severe drought and dust conditions, physiological performance and seedling growth were substantially impaired, increasing the likelihood of seedling mortality. Consequently, mitigating dust sources through wetland restoration, securing environmental water allocations, establishing stress-tolerant vegetation in dust-emitting areas, and strengthening regional cooperation for transboundary dust control and sustainable water resource management are recommended to reduce environmental stress and improve the resilience of Zagros forest ecosystems.
کلیدواژه‌ها [English]
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