Effect Of Drip Irrigation With Unconventional Water On The Soil Physical And Chemical Properties And Physiological Growth Of Cotton (Gossypium Hirsutum L.)

The development and utilization of brackish water and salt water resources is one of the important ways to alleviate the shortage of fresh water resources in agricultural production.But,salt stress caused by brackish water and salt water irrigation will affect the physical and chemical properties of soil and the physiological growth of crops.Drip irrigation of cotton under the film of water source under different salt gradients of 1 g/L,3 g /L,6 g/L,9 g/L and 12 g/L.The effects of soil moisture,soil conductivity,soil p H,soil hydrochemistry,photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）,intercellular CO₂ concentration（Ci）,initial fluorescence（F0）,maximum fluorescence（Fm）,potential activity（Fv/F0）,maximum photochemical efficiency（Fv/Fm）,cotton yield and water use efficiency were analyzed,The suitable salinity of irrigation water for drip irrigation of cotton under mulch was put forward.The results can provide the basis for the development and utilization of the underground brackish water and salt water resources and the sustainable development of irrigation agriculture.The main conclusions are as follows:（1）The salt in irrigation water will lead to the accumulation of salt in some soil,especially in the surface 0²0cm soil,but not obvious in the 60⁸0 cm soil.When the salinity is lower than 6g/L,the accumulated salt will don’t have a serious impact on the water absorption of cotton,and the soil moisture content suitable for cotton physiological growth should be between 10% and20%.（2）Under different salinity water irrigation conditions,the content of SO^2-₄,Ca²⁺,and Cl-is more in 0²0 cm soil.with the increasing of irrigation salinity,the cation of soil changes from Ca²⁺ to Mg²⁺ and K+ gradually,the anion changes from SO^2-₄and HCO^-₃to Cl-gradually,and the hydrochemical type changes from SO^2-₄·HCO^-₃-Ca²⁺·K+ to SO^2-₄·Cl--Ca²⁺·K+ gradually.（3）Under different salt irrigation treatments,the order of main root length from big to small was 3 g/L > 1 g/L > 6 g/L > 9 g/L > 12 g/L;In bud stage,comparing 1 g/L,6 g/L,9 g/L and 12 g/L with 3 g/L,the transpiration rate of cotton decreased by 10% 30%,net photosynthetic rate decreased by 20%⁴0%,and cotton yield decreased by 25%⁵5%.（4）Under the treatments of different mineralization degree condition,there is a negative correlation between irrigation mineralization degree and water use efficiency of cotton.The higher the irrigation mineralization degree of cotton,the lower the water use efficiency of cotton.On the contrary,the lower the irrigation mineralization degree of cotton,the higher the water use efficiency of cotton.The result suggests the highest water use efficiency is treatment B.Comparing 3 g/L with 6 g/L,9 g/L and 12 g/L,the water use efficiency（WUE）was increased by20%⁶0%.Under the condition of brackish water film drip irrigation,Comparing with 6 g/L,9g/L and 12 g/L,3 g/L can save 20%⁶0% of irrigation water.（5）Under the condition of 1 g/L⁶ g/L film drip irrigation,water-saving was achieved and water use efficiency was improved significantly under the condition of keeping cotton yield unchanged.The treatment of 3 g/L of irrigation water not only ensures the water demand of cotton growth,but also does not cause salt stress to plant physiological growth.It is suitable for drip irrigation under film.Under the treatment of 1 g/L,3 g/L and 6 g/L,cotton yield is higher.Integrating various factors.