ارزیابی برخی صفات بیوشیمیایی در چند گونه‌ زراعی و وحشی گندم تحت تنش خشکی

تنش خشکی یک تنش غیرزنده است که به عنوان یکی از عوامل مهم کاهش‌دهنده رشد محصولات کشاورزی در بیشتر نقاط جهان مخصوصاً ایران بوده و منجر به تنش اکسیداتیو می‌شود. به‌منظور بررسی تاثیر سطوح مختلف تنش خشکی بر برخی صفات ویژگی‌های بیوشیمیایی، پژوهشی در گلخانه تحقیقاتی دانشکده کشاورزی زابل به‌صورت آزمایش فاکتوریل در قالب طرح کاملاً تصادفی با سه تکرار در سال 1395-1396 انجام گرفت. فاکتور اول گونه‌های گندم (تائوشی، اسپلتوئیدز، اورارتو، شبرنگ، بهرنگ، سیستان، ارگ) و فاکتور دوم سطوح آبیاری (90، 70، 50 و 30 درصد ظرفیت زراعی) بودند. نتایج نشان داد که اثر تنش خشکی بر غلظت پروتئین، کلروفیل a، b، کاروتنوئید، آنزیم کاتالاز، سوپر اکسید دیسموتاز، آسکوربات پراکسیداز و مالون دی‌آلدئید تاثیر معنی‌داری داشت. این در حالی است که با افزایش تنش میزان آسکوربات پراکسیداز متغیر بود به‌طوری‌که ابتدا افزایش و سپس کاهش یافت. این وضعیت نشان‌دهنده فعال شدن سیستم آنتی‌اکسیدانی در گونه‌های مختلف گندم برای افزایش تحمل به خشکی است. پروتئین، کلروفیل و کاروتنوئید با افزایش تنش خشکی تا سطح 50 درصد ظرفیت زراعی ابتدا افزایش و با شدیدتر شدن تنش باعث کاهش این مقادیر شد. احتمالا فعالیت آنزیم‌های آنتی اکسیدانی مانع از تجزیه پروتیئن و سایر اجزاسلولی شده است. در این تحقیق رقم شبرنگ نسبت به دیگر ارقام برتری داشت در حالی که کمترین مقادیر مربوط به گونه هگزاپلوئید سیستان بود.

Evaluation of some biochemical traits in cultivars and wild species of wheat under drought stress

Introduction Wheat is the most widely grown crop in the world, which has the highest crop area.. Ageilops tauschii, Aegilops speltoides, Triticum urartu, are diploids In terms of ploidy level, diploid species (2n=2x=14), from wild relatives of wheat and, respectively, has a DD genome and a genome D agent in modern bread wheat, Includes BB genome and AA genome. Drought stress is an abiotic stress that is considered as one of the important factors in decreasing plant growth and crop production in most parts of the world, especially in Iran, and it leads to oxidative stress, Plants have different potent in drought stress in all aspects of development, including physiological, biochemical, morphological and anatomical, so plants use different strategies and protection systems against stress. The most important strategies are the change in antioxidant enzymes activity and increase or decrease in proteininduced proteolysis and changes in the chlorophyll and carotenoid levels. The aim of this study is to investigate the effect of different drought levels stress on some physiological traits in diploid (wild cultivars), tetraploid (durum wheat) and hexaploid (bread wheat) species. Materials and methods In order to investigate the effect of different drought stress levels on some biochemiccal characteristics, a research project was conducted in 20162017 in the greenhouse of Zabol Agricultural Faculty as factorial experiment in a completely randomized design with three replices. The first factor was wheat species and cultivars (Tauschii, Speltoides, Urartu, Shabrang, Behrang, Sistan, Argh) and the second factor was drought stress (90, 70, 50 and 30 percent of field capacity). The traits studied in this study were antioxidant activity (including superoxide dismutase, catalase and ascorbate peroxidase), protein, chlorophyll a, chlorophyll b and malondialdehyde activity. Data analysis was performed using SAS software version 9/9, the mean of data was analyzed by Tukey’s test (p≤0.01) and graph charts were drawn by Excel software. Results and discussion The results showed that drought stress had significant effect on the concentrations of protein, chlorophyll a and b, carotenoid, catalase, superoxide dismutase, ascorbate peroxidase and malondialdehyde. That’s while with increasing the stress, the amount of ascorbate peroxidase varied, so that initially increased and then decreased. This represents the activation of antioxidant system in different wheat species to increase drought tolerance. With increasing drought stress up to 50 percent of field capacity, protein, chlorophyll and carotenoid amounts increased, but with the higher stress these amounts decreased. So it can be stated that to reduce the damage caused by water shortages in the higher stress, the plant has resisted to drought by increasing proteolysis and decreasing protein amount. Conclusion Due to the fact that plants tolerate some degrees of stress, the studied wheat cultivars were able to tolerate 50 percent of field capacity, and with increasing the stress subsequently to higher levels, they showed a decrease in activity and some biochemical traits. Among all the cultivars, Shabrang showed the highest values. Therefore, in this experiment as it was shown by other researches, the superiority of this cultivar has been determined. Also, the lowest amount was related to Sistan cultivar, which received the lowest values, However, during the process of applying stress, the savage wheat cultivars were superior for these traits. Therefore, further studies are necessary on the wild wheat varieties. Acknowledgements We are thankful to Dr. Kamal ghasemibezdi and members of the Faculty of Agriculture Research Laboratory.