Effects of controlled release of N fertilizer on cotton yield

The effect of controlled release of nitrogenous fertilizer on photosynthesis and yield of cotton was studied under field conditions.The results show that controlled release N treatment at 150kg/hm2 increases LAI,Fv/Fm,ΦPSⅡ and Fv/Fo in cotton leaves at peak flowering and bolling stages,which subsequently enhances the CAP and boll number per plant,and boll weight.The yield of unginned cotton and fertilizer use efficiency increase by 10.3% and 10.2%,respectively,compared with that of CK.Controlled release N treatment with less than 120kg/hm2 of N gives almost the same yield as CK,but increases fertilizer use efficiency by 29.0%,and saves labor and time when used only as base fertilizer.