Effects of Controlled Release N Fertilizer on Photosynthesis Property and Yield of Cotton

Effects of controlled release N fertilizer that was applied by different quantity and methods vs.Urea(N 150 kg·hm~(-2))on photosynthesis property and yield of cotton had been studied in fields,so that the theoretical basis was provided for application and spread of controlled release N fertilizer expending in cotton production.The results showed that,the controlled release N treatment increased ФPSⅡand Fv/Fo in cotton leaves at bolling and boll opening stage,and enhanced CAP,boll number plant-1 and boll weight.Compared with CK,the seed cotton yield and fertilizer use efficiency of each treatment were as follow:(1) equal N(N 150 kg·hm~(-2)) used as base fertilizer increased seed cotton yield and N use efficiency by 10.3% and 10.2 %,respectively;(2) equal N(N 150 kg·hm~(-2))used as base fertilizer and topdressing treatment(1∶1) increased seed cotton yield and N use efficiency by(22.5%) and 22.4%,respectively;(3) N 120 kg·hm~(-2) with 1∶1 base fertilizer and topdressing increased seed cotton yield and N use efficiency by 12.3%and 40.3%,respectively;(4) N 120 kg·hm~(-2) used as base fertilizer increased seed cotton yield and N use efficiency by 3.2% and 29.0 %,respectively.In a word,cotton yield was increased in all the treatments of controlled release N fertilizer under this experimental conditions compared with CK,among which the highest yield was achieved by applying controlled release N fertilizer 150 kg·hm~(-2),half used as base fertilizer and half used as topdressing in early flowering stage.