Effects of Water-nitrogen Coupling on the Development and Yield of Cotton in Drip Irrigation under Film

Under field production conditions,the experiment was made to research the effect of water-nitrogen coupling on cotton development and yield under drip irrigation in 5 field spots.The results showed that water have more the effect than nitrogen on the cotton dry matter accumulation、 nutrient accumulation and seed cotton yield.Mathematical model for cotton yield and its main affecting factors water and nitrogen its was established,which was,water and nitrogen have the effect of increasing cotton yield,but water-nitrogen coupling was negative effect,when water and fertilizer supplies was excessive,the cotton yield will decrease.The optimizing fertilization could enhanced the effect of irrigation for increasing yield.The cotton yield will reach the top which is 5999.98 kg/hm2,when W is 4112.8 m3/hm2 and N is 270.47 kg/hm2.