اثر تنش‎ کم‌آبیاری بر عملکرد وش، ویژگی‌های فیزیولوژیک و آنتی‌اکسیدان‌های غیر آنزیمی ارقام پنبه (.gossypium hirsutum l)

به‌منظور بررسی پاسخ 10 رقم پنبه به تنش کم‌آبیاری، آزمایشی به‎صورت کرت‌های خرد شده در قالب طرح بلوک‌های کامل تصادفی با 3 تکرار در مزرعه آموزشی و تحقیقاتی دانشگاه گنبدکاووس در دو سال 1400 و 1401 انجام شد. عامل اصلی تنش کم‌آبیاری در دو سطح شامل دو مرتبه آبیاری (تشکیل غنچه و شروع گل‌دهی) و عدم تنش چهار مرتبه آبیاری (تشکیل غنچه، شروع گل‌دهی، شروع تشکیل غوزه و ابتدای باز شدن غوزه) و عامل فرعی ارقام پنبه در 10 سطح شامل شایان، ساحل، سپید، ساجدی، گلستان، لطیف، ارمغان، پرتو، مای و لودوس بودند. نتایج تجزیه واریانس مرکب نشان داد که مالون‌دی ‌آلدئید و عملکرد وش تحت تاثیر سال قرار گرفتند و هر سال جداگانه مقایسه میانگین انجام شد، سایر صفات کلروفیل a،b ، کلروفیل‌کل، کاروتنوئید، پرولین و قندهای محلول تحت تاثیر متقابل تنش کم‌آبیاری × رقم قرار گرفتند. رقم گلستان از نظر میزان پرولین و قندهای محلول به‌ترتیب با 2/91 و 27/06 بیش‌ترین میزان در شرایط تنش ‌کم‌آبیاری به خود اختصاص داد. بیش‌ترین عملکرد وش طی سال اول و دوم در شرایط عدم تنش متعلق به رقم ساجدی به‌ترتیب با 4596 و 4593 کیلوگرم در هکتار و کمترین عملکرد وش در شرایط تنش کم‌آبیاری ‌سال اول و دوم متعلق به رقم سپید به‌ترتیب با 1649 و 1756 کیلوگرم در هکتار بود. نتایج ضرایب همبستگی نشان داد ارقام گلستان و ساجدی جز ارقام متحمل به تنش و رقم‌های ساحل و سپید جز ارقام حساس به تنش‌ آبی و با عملکرد ضعیف بوده بقیه ارقام جز ارقام نیمه حساس به تنش آبی معرفی شدند.

effect of low irrigation stress on yield, physiological characteristics and non-enzymatic antioxidants of cotton cultivars (gossypium hirsutum l.)

introduction:  due to iran’s location in the arid and semi-arid region of the world, the possibility of drought is high. therefore, implementing low irrigation to increase the efficiency of limited water resources is a scientific solution to reduce water consumption. on the other hand, irrigation deficit in cotton  is the most important factor limiting production worldwide, which indicates the need for optimal use of water resources to determine the real water needs of cotton plants. therefore, development and introduction of drought tolerant cultivars and useful method to improve water productivity and efficiency in the face of drought and water scarcity. the aim of this experiment was to evaluate cotton cultivars by measuring traits related to photosynthetic pigments and yield in order to select drought tolerant cultivars.materials and methods: the present study, evaluated physiological traits of 10 cotton cultivars that were known as tolerant cultivar under irrigation deficit based on the measurement of traits and mechanisms of drought tolerance split-plot arrangement using randomized complete blocks design with three replications in 2021 and 2022 years, in the educational and research farm of gonbadkavos university (golestan province), iran. experimental research includes two different irrigation regime the main factor of irrigation stress in two levels including low irrigation stress (two times of irrigation in the stages of bud formation and beginning of flowering) and no stress (four times of irrigation in the stages of bud formation, beginning of flowering, beginning of bud formation and beginning of bud opening) and the factor sub-types of cotton were included in 10 levels (shayan, sahel, sepid, sajidi, golestan, latif, armaghan, parto, mai and lodos). the studied traits include physiological characteristics such as chlorophyll a, b and carotenoids, proline and boll yield. photosynthetic pigments were measured by spectrophotometer and its concentration was performed by arnon (1967) method.results and discussion: based on the results of this experiment, cultivars with low irrigation stress treatments showed a significant difference in terms of traits related to photosynthetic pigments and non-enzymatic antioxidants and their yield. the study of compound analysis of interaction effect of cultivars in the stress of low irrigation during two crop years showed a significant difference in the yield of vash and malendialdehyde. most of the studied traits were affected by the intensity of low irrigation stress and growth stage. the amount of proline increased with the increase of stress so that at the medium stress level of two stages of irrigation (bud formation and beginning of flowering) it increased significantly compared to the condition of no stress. the amount of chlorophyll a was affected by the intensity of stress, but there was no significant change in the amount of chlorophyll b. in the first and second year, the highest yield of rice in non-stress conditions belonged to sajidi variety with 4596 and 4593 kg/ha-1, respectively, and the lowest yield in water stress conditions in the first and second year belonged to sepid variety, with 1649 and 1756 kg/ha-1, respectively. the decrease in the yield of cotton was due to the decrease in the number of bolls in the plant under the condition of low irrigation stress.conclusion: the results of this study indicated the traits of  tolerance cultivars under irrigation deficit. also, cultivars showed different reactions to the studied traits.  according to the results of the research and the correlation coefficients between the traits, among the water stress tolerant cultivars studied, golestan and sajidi cultivars are among the stress tolerant cultivars, sahil and sepid cultivars are the sensitive cultivars to water stress, and the other cultivars are the semi-sensitive cultivars. water stress was introduced.