Effect of Water and Fertilizer Coupling on Photosynthetic Characteristic and Yield of Cotton in Arid Area

Effect of water and fertilizer coupling on photosynthetic characteristics of Zhongmian 41 cotton was studied by field experiments under surface irrigation with water and fertilizer coupling 15 treatments.The results showed that under different treatments ,the photosynthetic rate could maintain a high level on 20.7 μmol/m2·s in the full boll stage of cotton,when the W was 5 475 m3/hm2 ,the N was 362.4kg/ hm2 and the P was 135.15 kg/hm2,the treatment has a significant negative correlation with others.The dirunal variation of the N3P2W2 treatment of leaf photosynthetic rate showed single peak, the N3P2W2 treatment can resolve the Pn sleep at noon phenomina;The regression equation of treatmens and net photosynthetic rate showed that when the treatment of the was 5 425.8 m3/hm2 ,the N was 362.4 kg/hm2 and the P2O5 was 135.15 kg/hm2,the net photosynthetic rate of cotton was the highest level on 19.37 μmol/m2·s; The regression equation of photosynthetic characteristics and yield showed that when the treatment of the net photosynthetic rate was 19.78 μmol/m2·s,the rear earth was 70.94%, the yield of cotton was the highest level on 3 873.3 kg/hm2.