Evaluation of climate change effects on water requirement of cotton crop Khorasan Razavi province

Estimation of plant water requirement under climate change conditions is important for planning in the direction of irrigation principles and water resources management in the agricultural sector. Cotton is one of the most important industrial products in the country. In this study, based on the data of meteorological stations in the base period and the output of total atmospheric circulation models from the next period to 2060, ETo changes and deviations and the water requirement of cotton crop in Khorasan Razavi were investigated. Evaluation of the province based on observational data showed that most of the province's rainfall occurs in the cold period of the year, especially in March or March to late April and mid-May. Examination of the simulated data showed that in the next period up to 2061; the amount of air temperature in the region will increase. Monthly precipitation in the period (2020-2040) decreased compared to the base period, but in the decades (2041-2061) increased compared to previous decades and reached close to normal. In fact, in the near decade 2060, the amount of rainfall will increase slightly compared to the next decades; These conditions can not be stabilized due to the increase in air temperature, a slight increase in precipitation. Studies have shown that the amount of Eto or reference evapotranspiration in the future period will increase compared to the base period and the past due to the increase in air temperature. Based on the increase in reference evapotranspiration, the water requirement of cotton growth stages, including the initial, intermediate and final stages, will also increase. In terms of length of growth period; The highest amount of water requirement will occur in the middle period of cotton growth. In terms of spatial distribution and dispersion; The northern half of the province and the center of the province have the highest amount of reference evapotranspiration and water requirement due to altitude and mountainous conditions (Quchan, Dargaz, Chenaran, Neishabour and Torbat Heydariyeh). The need for serious attention to the optimal management of water resources and planting resistant crops with higher adaptability is important.Estimation of plant water requirement under climate change conditions is important for planning in the direction of irrigation principles and water resources management in the agricultural sector. Cotton is one of the most important industrial products in the country. In this study, based on the data of meteorological stations in the base period and the output of total atmospheric circulation models from the next period to 2060, ETo changes and deviations and the water requirement of cotton crop in Khorasan Razavi were investigated. Evaluation of the province based on observational data showed that most of the province's rainfall occurs in the cold period of the year, especially in March or March to late April and mid-May. Examination of the simulated data showed that in the next period up to 2061; the amount of air temperature in the region will increase. Monthly precipitation in the period (2020-2040) decreased compared to the base period, but in the decades (2041-2061) increased compared to previous decades and reached close to normal. In fact, in the near decade 2060, the amount of rainfall will increase slightly compared to the next decades; These conditions can not be stabilized due to the increase in air temperature, a slight increase in precipitation. Studies have shown that the amount of Eto or reference evapotranspiration in the future period will increase compared to the base period and the past due to the increase in air temperature. Based on the increase in reference evapotranspiration, the water requirement of cotton growth stages, including the initial, intermediate and final stages, will also increase. In terms of length of growth period; The highest amount of water requirement will occur in the middle period of cotton growth. In terms of spatial distribution and dispersion; The northern half of the province and the center of the province have the highest amount of reference evapotranspiration and water requirement due to altitude and mountainous conditions (Quchan, Dargaz, Chenaran, Neishabour and Torbat Heydariyeh). The need for serious attention to the optimal management of water resources and planting resistant crops with higher adaptability is important.Estimation of plant water requirement under climate change conditions is important for planning in the direction of irrigation principles and water resources management in the agricultural sector. Cotton is one of the most important industrial products in the country. In this study, based on the data of meteorological stations in the base period and the output of total atmospheric circulation models from the next period to 2060, ETo changes and deviations and the water requirement of cotton crop in Khorasan Razavi were investigated. Evaluation of the province based on observational data showed that most of the province's rainfall occurs in the cold period of the year, especially in March or March to late April and mid-May. Examination of the simulated data showed that in the next period up to 2061; the amount of air temperature in the region will increase. Monthly precipitation in the period (2020-2040) decreased compared to the base period, but in the decades (2041-2061) increased compared to previous decades and reached close to normal. In fact, in the near decade 2060, the amount of rainfall will increase slightly compared to the next decades; These conditions can not be stabilized due to the increase in air temperature, a slight increase in precipitation. Studies have shown that the amount of Eto or reference evapotranspiration in the future period will increase compared to the base period and the past due to the increase in air temperature. Based on the increase in