اثر تنش خشکی روی فعالیت آنزیمی آنتی‌اکسیدان و محتوای کلروفیل در ژنوتیپ‌های پیشرفته عدس (lens culinaris medik)

مطالعه حاضر جهت بررسی اثرات تنش خشکی روی فعالیت آنزیمی و محتوای کلروفیل 12 ژنوتیپ پیشرفته عدس در ایستگاه تحقیقات کشاورزی اردبیل و بخش مرکزی شهرستان گرمی در سال‌ زراعی 95/1394 به صورت کرت های خرد شده و برپایه طرح بلوک های کامل تصادفی اجرا گردید شرایط دیم و آبیاری تکمیلی به عنوان عامل اصلی و ژنوتیپ‌ها به عنوان عامل فرعی در نظر گرفته شدند. نتایج نشان داد که میزان پرولین، کاروتنوئید، محتوای کلروفیل a و b در اردبیل معنی دار و کمتر از گرمی شد اما فعالیت آنزیم پراکسیداز ، بیشتر از گرمی بود. در شرایط دیم آنزیم آسکوربات پراکسیداز بیشتر از شرایط آبیاری تکمیلی شد. عملکرد دانه در شرایط دیم 22 درصد کمتر از شرایط آبیاری تکمیلی است. میزان کاروتنوئید و محتوای کلروفیل در بافت برگ ها در گیاهان کشت شده در گرمی بیشتر از اردبیل می باشد. بیشترین میزان فعالیت آنزیم پراکسیداز مربوط به ژنوتیپ ill6037 (بیله سوار ) و بیشترین میزان پرولین مربوط به ژنوتیپ شماره 12 بود. بیشترین میزان عملکرد دانه در منطقه گرمی و ژنوتیپ شماره 12 ثبت شد (1902 کیلوگرم در هکتار) همبستگی مثبت و معنی دار بین میزان پرولین، درصد پروتئین دانه و فعالیت آنزیم پراکسیداز وجود داشت. همچنین همبستگی مثبت و معنی دار بین عملکرد دانه با کاروتنوئید، کلروفیل‌های a، b بود اما بین عملکرد دانه و فعالیت آنزیم‌ آسکوربات پراکسیدازهمبستگی منفی وجود داشت. نتیجه گیری نهایی این بود که هر چقدر شرایط رشد برای گیاه مهیاتر شود محتوای کلروفیل گیاه بالا و عملکرد افزایش می یابد همچنین در شرایط تنش میزان پرولین و آنزیم پراکسیداز در گیاه بالا می‌رود. و باعث افزایش مقاومت ژنوتیپ ها به تنش خشکی می شود.ضمنا با دو بار آبیاری آن هم بصورت محدود، عملکرد دانه در شرایط آبیاری تکمیلی 22 درصد بیشتر از شرایط دیم شد.

The effect of drought stress on antioxidant enzyme activity and chlorophyll content of some advanced genotypes of lentil (Lens culinaris Medik)

IntroductionDrought is one of the most important environmental stresses that influence various growth steps of the plant including germination, plantlet establishment, and production all over the world (Bacilar et al., 2007; Ben Ahmad et al., 2009). Drought stress has significantly increased in recent years because of changes in climate and increasing CO2 levels. Therefore, identification of the resistant plant varieties against drought stress in a necessity. Investigation the enabling mechanisms of plants to adapt to drought stress and protect their growth in that condition can help to select the resistant plants against drought stress to be cultivated in dry and semidry regions. Identification of the physiological mechanisms Lentil with the scientific name of Lens culinaris is from leguminous, oneyear, longday, self pollinated, and diploid family (2n=14) with mean 5.28% protein. Lens culinaris is resistant to drought. Materials and methods12 Lens culinaris genotypes (Table 1) were examined in rainfed and deficit irrigation conditions in 20152016 agricultural years as the split spots based on randomized complete block designs with three repetitions whose main irrigation factor was in 2 levels (rainfed and deficit) and the secondary factor of genotypes in two individual Ardabil agriculture research stations and central part of Germi city in different conditions and climates to evaluate the genetic varieties of Lens culinaris cultivars, screening the quantitative indexes of resistance against drought, and identification of the resistant cultivars against drought. All plots were simultaneously irrigated in two steps of flowering and pot filling in 10ml in deficit irrigation treatment in each region and weren’t irrigated in stress treatment or rainfed and just raining was used up to the end of harvest. Each test unit was made of 4 cultivation line with 4m length, 30cm row distance, and 133 bushes in each row. Hand weeding was done in several steps to fight with weeds. Each genotype is harvested in proportion to its physiological consideration. In this step, two edge lines and 0.5m of two middle lines end were omitted to remove edge effect. Harvest was with hand. Seed performance was determined after threshing and separating the seeds from the straw based on seed weight (gr). Physiological characteristics were measured after the plant sheathing in both rainfed and deficit irrigation typesResults and discussionTable of the combined variance analysis (Table 1) showed that the significant difference was observed among proline, chlorophyll a and chlorophyll b and peroxidase enzyme values of two cultivation methods, the comparison of the mean chlorophyll a and chlorophyll b (ml/gr) of wet weight in Germi region was 0.22 and 0.079 with the significant difference from Ardabil region. The reaction of chlorophyll a and chlorophyll b to drought stress may be resulted by the plant metabolism tolerance in addition to the genetic differences against drought, and lack of the significant reaction between chlorophyll to stress can be attributed to the growth reduction in leaf. There was a significant difference in proline (μm/gr of wet weight) in Germi and Ardabil, but the amount of enzyme peroxidase (μgr of enzyme/gr of leaf) was higher in Ardabil. Proline accumulation is a popular physiological response of plants to the extensive range of bio and nonbio stresses (Geravandi et al., 2011). The maximum imposed damage by drought stress was for proline of Germi; as though, stress increased 23% of proline than Ardebil condition. In Gunes et al. (2008) research, drought stress after pollination significantly increased proline. There was a significant difference between rainfed and deficit irrigation conditions based on variance analysis. Bilesavar cultivar was considered as a control sample with the maximum peroxidase enzyme. ConclusionsThe results of this test show that in rainfed cultivation (drought stress) enzyme activity of the antioxidant and peroxidase, ascorbate peroxidas, proline and some characteristics for resistance plant against drought stress are increase.