Effects of nitrogen fertilization on uptake and utilization of NPK and yield and quality of hybrid cotton.

Effects of nitrogen application rates on uptakes and utilizations of nitrogen(N),phosphorous(P),potassium(K) and yields and quality of hybrid cotton are studied under high yield cultivated conditions.The results show that accumulative amounts of N,P and K in hybrid cotton plants are increased when more nitrogen fertilizer are applied,especially at the later growth stages of the hybrid cotton.The yield is highest when N 300 kg/ha is applied,which is increased by 0.9% of the yield under the N 225 kg/ha treatment,and the difference is not significant.When increasing N fertilizer amounts,the nutrient utilization efficiencies of N,P and K are increased,however the N fertilizer utilization rate is decreased.The fiber length and fiber strength are increased under the N fertilization,but there are not significant difference among different nitrogen application rates.