Effects of saline water irrigation on soil water-heat-salt variation and cotton yield and quality

To make full use of saline water resources, the effects of irrigation with saline water of different salinity on soil water-heat-salt variation, cotton growth, yield and fiber quality were studied by field contrast experiment. The irrigation water salinities of four treatments were 1 (S1), 3 (S2), 5 (S3), 7 g/L (S4), respectively. Results show that the soil water content in depth of 0~40 cm and the temperature at 5cm soil layer have little differences under every treatment during the cotton growing period. Both of them increase with the salinity. The differences of soil electrical conductivity in the treatments are significant. The higher salinity of irrigation water, the higher the soil electrical conductivity is. The leaching efficiency of rainfall on soil salt is 29.40%~40.40% under each treatment at the end of cotton growth. The profile distribution of soil water and salt are restrained by soil texture, rainfall and water consumption due to cotton evapotranspiration. In drought time, soil is dry and salt accumulates in surface. But in wet period the results are opposite. The seedling rate, plant height, largest leaf area per plant and pro-frost yield of cotton decrease with the irrigation water salty rise. The cotton yields of the treatments from high to low are S2, S1, S3, S4, respectively, among which the difference between S4 and S1 treatments reaches significant level. Saline water irrigation produced a negative impact on fiber quality by changing Mic value, especially for S4 treatment. The study provides an important theoretical support for developing saline water irrigation of cotton.