اثر محلول‌پاشی سالیسیلیک اسید و کود ورمی کمپوست بر شاخص‌های فیزیولوژیکی و کیفی دو رقم فلفل شیرین (.capsicum annuum l) تحت تنش سرما

فلفل شیرین از مناطق گرمسیری منشا می‌­گیرد و حساس به سرما است؛ بنابراین شناخت مکانیسم دفاعی گیاه فلفل در مقابل دمای کم ضروری است. در این مطالعه اثر محلول‌پاشی سالیسیلیک‌ اسید و کود آلی ورمی کمپوست روی ارقام مختلف فلفل شیرین تحت تنش سرما موردبررسی قرار گرفت. آزمایش به­صورت اسپیلیت‌پلات فاکتوریل در قالب طرح بلوک‌های کامل تصادفی در سه تکرار در سال زراعی 97- 1396 در محیط گلخانه‌ای واقع در مشهد اجرا شد. عامل اصلی تیمار دمایی در دو سطح {دماهای 2± 9 درجه سلسیوس (تنش سرما) و 2±23 درجه سلسیوس (شاهد)} و عامل فرعی شامل دو رقم فلفل شیرین {california wonder (سبز)، roxcy (زرد)}، سالیسیلیک اسید (صفر-200-300 میکرومول) و ورمی کمپوست (20 درصد حجمی) بود. نتایج نشان داد که تنش سرما باعث تغییرات برخی خصوصیات فیزیولوژیک و کاهش عملکرد میوه گردید. حداکثر درصد ماده خشک (17.2%) و اسیدیته قابل تیتراسیون (13.6%) در تیمار عدم تنش سرمایی و مواد جامد محلول (5/03 بریکس)، کربوهیدرات‌ها (mg.g-1 174.5) و فعالیت آنتی‌اکسیدانی (90.3%) در تیمار تنش سرمایی حاصل گردید. بیشترین عملکرد میوه در بوته (740 گرم در بوته) در تیمار تاثیر متقابل عدم تنش سرمایی و محلول‌پاشی سالیسیلیک‌ اسید μmol 300 به دست آمد. بیشترین مقدار فلاونوئید (mg.100g^-1 fw 159.4) در تیمار سالیسیلیک‌ اسید μmol 200 حاصل شد. همچنین بیشترین مقدار بتاکاروتن (mg kg-1 346.4)، لیکوپن (mg kg^-1 152.9) و ویتامین ث (mg.100 g^-1 142.52) در تیمار سالیسیلیک اسید μmol 300 مشاهده شد. با توجه به نتایج می‌توان اظهار داشت تنش‌های سرمایی تاثیرات نامطلوبی بر شاخص‌های کیفی و عملکرد فلفل شیرین در محیط گلخانه می‌گذارد و کاربرد محلول‌پاشی سالیسیلیک‌ اسید در بعضی از صفات اثرات سوء تنش سرما را تعدیل کرد.

effect of foliar application of salicylic acid and vermicompost on physiological and qualitative indices of two sweet pepper (capsicum annuum l.) cultivars under cold stress

introductionsweet pepper is a rich source of essential vitamins and minerals. on the other hand, pepper fruit contains high levels of antioxidants and beneficial substances such as vitamin c, carotenoids and phenolic compounds. it also contains high concentrations of potassium. these compounds has nutritional and antioxidant capacity. sweet pepper originated from the tropical region, which is sensitive to cold. therefore, it is necessary to know the defense mechanism of the pepper plant against low temperatures. in this study, the effect of foliar application of salicylic acid and vermicompost on different cultivars of sweet pepper under cold stress has been studied.materials and methodsthe experimental design was a factorial split-plot experiment in a randomized complete block design with three replications in a greenhouse located in mashhad in the crop year 1396 and 1397. cultivation was performed hydroponically. the main factor of temperature treatment had two levels [9 ± 2°c (cold stress) and 23 ± 2°c (optimum)] and the sub factor consisting of two sweet pepper cultivars (green, yellow) and different amounts of salicylic acid (the dose of 0 μmol salicylic acid was used as control group, 200, 300 μmol) and vermicompost). sampling of the plants at the end of the growing season, to measure the physiological characteristics and quality were randomly.results and discussionthe results showed that there was no significant difference between different cultivars in most traits except vitamin c, beta-carotenoids and lycopene. maximum dry matter (17.2g), ta (13.6 g l-1) in non-stress cold treatment, and soluble solids (5.03 brix),, carbohydrates(174.5 mg g-1), and anti-activity oxidation (90.3%)  were obtained in cold stress treatment. damage due to cold stress destroyed the structure of many membrane lipids and resulted in an increase in the amount of antioxidant compounds. soluble solids are known to be key components in increasing cold resistance. an increase in the amount of soluble solids in winter is part of the plant’s adaptation mechanism to cold. the highest yield of fruit per plant(740 g) was obtained in non-cold stress treatment plus salicylic acid 300 μmol. because salicylic acid in plants improves yield and yield components. maximum of flavonoids (159.4 mg g-1) was obtained in salicylic acid 200 μmol. flavonoids are a large group of phenolic compounds in plants that increase their production in environmental stresses by increasing the activity of pal enzyme. on the other hand, the use of salicylic acid as a stressor causes the production of a wide range of flavonoids. the highest amount of beta-carotene and lycopene were obtained in cold stress treatment, yellow cultivar, and salicylic 300 μmol. decreased content of carotenoids under stress can be due to oxidation by active oxygen and damage to their structure. increased photosynthetic pigments under sa treatment indicate the protective effect of this growth regulator on photosynthesis and photosynthetic pigments of stressed plants. maximum vitamin c was obtained in cold stress treatment (140.7 mg 100 g-1, yellow cultivar (134.7 mg.100g-1), and salicylic 300 μmol (142.52 mg.100 g-1).conclusionaccording to the results, the of the present study show that use of salicylic acid foliar application modulates the effect of cold stress on the physiological and functional parameters of sweet pepper so that sa can improve cold tolerance by regulating the activities of apoplastic antioxidative enzymes. therefore, it is suggested that due to sudden changes in temperature due to climate change and the destructive effects of temperature stress, especially cold, on plants, more and more complete research should be done to identify the effects of these stresses and ways to deal with them.