Effects of Nitrogen Application Rates on Growth and Yield in Hybrid Cotton-Biaoza A_1

Effects of different nitrogen(N) fertilizer rates on growth and yield of hybrid cotton were investigated through a field experiment.Four N application levels were set as 0,150,300 and 450 kg/hm2.Fast rising periods of dry matter and nitrogen accumulation were delayed with N application rate increased,but the maximum rates of dry matter and nitrogen accumulation were increased.For Biaoza A1,the fast rising period of dry matter and nitrogen accumulation were from early flowering stage to boll full development stage and continued for about 40 days.The total dry matter weight and N accumulation were increased with N application increased.Boll Number,boll weight and seed cotton yield were influenced significantly by N application rates.With N application increasing,boll weight was increased.The highest of boll number and yield were found in 300 kg/hm2 treatment,and then were 300 and 150 kg/hm2 treatments;the lowest was 0 kg/hm2 treatment.Apparent nitrogen recovery was 41%～55% and the suitable nitrogen application rate was 310-340 kg/hm2 under this condition.