Experimental Research On Suitable Irrigation Management Based On Meteorological Information For Film Mulched Drip Irrigation Cotton In Southern Xinjiang

The process of crop water use is closely related to the meteorological environment.In order to explore the feasibility of irrigation decision-making based on meteorological information and guide the scientific irrigation of cotton under drip irrigation under mulch,field experiments were conducted in Alar,South Xinjiang,in the growing seasons of 2017 and 2018.The crop evapotranspiration?ET_c?and precipitation?P?were monitored in real time according to the meteorological information collected by automatic weather stations,when the difference between evapotranspiration and precipitation?ET_c-P?was accumulated.Irrigation will be carried out when it reaches 30 mm.Three irrigation quota treatments,T1:24 mm,T2:30 mm and T3:36 mm,were set up,which were 0.8,1.0 and 1.2 times ofET_c-P respectively.At the same time,an irrigation mode commonly used in local production was set up as control?T4?treatment,and repeated three times.During the experiment,the dynamic changes of soil moisture and salinity,plant physiological indexes,seed cotton and lint yield,cotton quality,irrigation water use efficiency and field water use efficiency were monitored and analyzed.The calculated results of single crop coefficient method were tested by measured crop evapotranspiration,and the SIMdual_Kc double crop coefficient model was validated to determine the precise estimation method of cotton field evapotranspiration in Alar region of South Xinjiang.The main conclusions of the study are as follows:?1?During the growth period of cotton,soil moisture and salinity fluctuated with the growth and development of cotton and irrigation.The shallower the soil layer,the greater the fluctuation range.Among them,the change of water content was mainly concentrated in the 0⁴0 cm soil layer in the main root zone of cotton,while the change of soil layer below 40 cm was small.The fluctuation period of soil water content is the same as that of irrigation.Before each irrigation,it is at a relatively low value.After irrigation,it increases significantly.The larger the irrigation amount,the higher the soil water content.In the main root zone,the larger the irrigation quota,the lower the soil salinity.Conventional irrigation treatment resulted in excessive irrigation,deep seepage and accumulation of salt in soil below 40 cm.Based on Meteorological information,the soil salt content in the main root zone was inversely proportional to the irrigation quota,and there was no significant difference between the treatment with the highest irrigation quota and that with conventional irrigation.?2?The irrigation quota of T1 treatment is too small,water stress occurs,plant growth and development are affected due to water deficit,plant height and leaf area are at the lowest level in all treatments,reproductive growth is ahead of time,yield is significantly lower than other treatments;T4treatment is too high,resulting in plant development lag,greedy late maturity.According to the treatments of T1,T2 and T3 under the guidance of meteorological information,the water consumption in the growth period of 2017 and 2018 was 317.69 mm to 419.56 mm and 282.96 to 378.34 mm,respectively.The larger the irrigation quota,the more water consumption in the whole growth period,but they were significantly lower than the total water consumption of 522.1 mm and 421.36 mm under the conventional irrigation treatment.The yield of T3 treatment was not significantly different from that of conventional irrigation treatment.It indicated that the combination of 30 mm irrigation and 36 mm irrigation quota could significantly improve the irrigation water use efficiency and field water use efficiency under the condition of ensuring no reduction of cotton yield.It was suitable for drip irrigation of cotton under the guidance of meteorological information in southern Xinjiang.?3?Cotton field evapotranspiration calculated by single crop coefficient method shows the same trend as the measured value,but the accuracy is low.SIMdual Kc double crop coefficient model can accurately simulate the changes of crop evapotranspiration in southern Xinjiang to meet the needs of irrigation decision-making;SIMdual Kc double crop coefficient model can estimate the suitable basic crop coefficient K_cb,K_cbini,K_cbmid and K_cbend of film mulched drip irrigation cotton in southern Xinjiang are 0.2,1.15 and 0.58,respectively.