برآورد شاخص ‌های بهره‌وری آب آبیاری و عملکرد زراعت پنبه در شرایط مرسوم کشاورزی شهرستان ‌های لارستان، داراب و فسا (مطالعه موردی: استان فارس)

شناسایی و رفع موانع تولید گیاه پنبه، یکی از مهم‌ترین کالاهای استراتژیک، از قبیل تغییرات اقلیمی و چالش های خشکی و کم آبی از یک سو و ناپایداری عملکرد و کیفیت نامناسب محصول از سوی دیگر، اهمیت توجه به تحقیقات کاربردی و انتقال دانش فنی به عرصۀ تولید را دو چندان کرده است. تحقیق حاضر با هدف اندازه‌گیری آب آبیاری، عملکرد و بهره‌وری آب آبیاری پنبه در شرایط مرسوم در شهرستان‌های لارستان، داراب و فسا در استان فارس به اجرا درآمده است. بدین منظور 20 مزرعه (18 مزرعه آبیاری سطحی و 2 مزرعه آبیاری قطره‌ای نواری) منتخب در شهرستان‌های لارستان، داراب و فسا انتخاب و  عملکرد محصول و میزان آب آبیاری در آن ها اندازه گیری شد. نتایج نشان داد که میانگین شاخص‌های عملکرد، میزان آب آبیاری و بهره‌وری آب آبیاری پنبه در 18 مزرعۀ منتخب استان که با روش سطحی آبیاری می‌شدند، به ترتیب برابر 4450 کیلوگرم بر هکتار، 9899 مترمکعب بر هکتار و 0/5 کیلوگرم بر مترمکعب به دست آمد. بر اساس نتایج این تحقیق، توصیه می‌شود از یک سو تاریخ کشت و برداشت به ترتیب 20 خردادماه و اول آبان ماه رعایت گردد. از سوی دیگر با قبول 20 تا 25 درصد کم‌آبیاری تنظیم شده در دوره رشد، میزان آب آبیاری بهینه، بدون لحاظ کردن ضریب آبشویی برای گیاه پنبه، در این مناطق با روش آبیاری سطحی بین 9000 تا 10000 مترمکعب در هکتار در نظر گرفته شود. همچنین تاکید می‌شود کشاورزان پیش از کاشت پنبه، از خاک نمونه‌برداری کنند و طبق توصیه‌های کارشناسان،کوددهی بهینه را دنبال کنند.

estimation of irrigation water productivity indicators and cotton cultivation yield in conventional agricultural conditions of larestan, darab and fasa cities (case study: fars province)

recognizing and removing production obstacles such as climate changes and drought and water shortage challenges, on one hand, and performance instability and inappropriate product quality, on the other hand, has doubled the importance of paying attention to applied research and transfer of technical knowledge to the field of production. therefore, the present research was conducted with the aim of investigating the impact of farmers’ management in different climates of cotton-producing areas of fars province on the irrigation water productivity index.methodologythis research was carried out in the field in order to determine the cotton irrigation water in the fields under the management of farmers during one cropping season (2018-2019) in larestan, darab and fasa areas in fars province. a total of 20 experimental farms were selected. registration of irrigation program and measurement of water source flow using wsc flume device and volumetric meter were also done. after determining the flow rate of the water source, according to the number of hours of irrigation, the applied irrigation water in each irrigation turn was determined in each of the selected fields. the simplest method that can be used in farmers’ fields to estimate the physical productivity of irrigation water of a plant is to measure the yield and amount of irrigation water during the cropping season. in order to estimate the pure water requirement of cotton in the study areas, first, the reference evapotranspiration was calculated using the eto-calculator software (raes, 2012) according to the fao penman-monteith method. the meteorological information used included daily average maximum and minimum air temperature, maximum and minimum relative humidity, wind speed at a height of 10 meters (m/s) and the number of sunny hours per day in a statistical period of 10 years. in order to determine plant coefficient values in different stages of cotton growth, first, according to field observations, the four stages of cotton growth were determined. then the plant coefficients related to each growth stage were selected based on the proposal of fao publication 56 (allen et al., 1998). considering the efficiency of 60 and 90% for surface and drip irrigation systems, respectively (abassi et al., 2015), the gross water requirement of farms was obtained.results and discussion the average yield of cotton in larestan, darab and fasa cities is 4300, 5775 and 3080 kg per hectare, respectively. as it is known, the lowest crop yield was obtained in fasa district, which could be due to high soil salinity. according to the research of nakhjavani moghadam et al. (nakhjavani moghadam et al., 2019), the average yield of cotton in the country is reported to be 3383.5 kg per hectare, which has increased by 27 and 70 percent in larestan and darab, respectively, and the cotton average yield in fasa is 9 the percentage has decreased. the average amount of irrigation water in selected farms and 18 farms that were irrigated by surface irrigation method was 9944 and 9899 cubic meters per hectare, respectively.