Water And Nitrogen Response Characteristics Of Hybrid Cotton Under Drip Irrigation

Water and nitrogen (N) are the main limiting factors affecting agricultural production in arid and semiarid regions. Improving the efficiency of these factors is, therefore, the target for improved management. Drip irrigation is considered to be the most efficient irrigation method, which can maximize water and nitrogen use efficiency. Effects of rate and frequency of water and nitrogen on growth and N uptake of hybrid cotton were investigated with a 2-year field experiment under drip irrigation conditions. In this study, the main objective is to envaulate the N uptake of hybrid cotton and the effects of different water and nutrient management practices.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 amount of N uptake in this stage accunted for 60-65% of total N uptake. Dry matter and N accumulation of hybrid cotton reached peak at full blossom stage. The 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.Dry mass, N uptake, and yield of hybrid cotton were influenced significently by water, nitrogen, and their interaction. Dry mass, N uptake, and yield of hybrid cotton increased with irrigation water increasing from 360 to 520 mm, and N increasing from 150 to 360 kg·hm^-2; but not affected by irrigation water at 600 mm and N at 450 kg·hm^-2, respectively.The rate and frequency of water and nitrogen significantly influenced nitrogen accumulation, dry mass and yield of hybrid cotton. Soil water content of 0-40 cm soil depth was maintained at higher level under higher irrigation frequency treatments. Dry mass, N uptake, and yield of hybrid cotton were increased significently under those treatments. Under 360 and 270 kg·hm^-2 of N rates, fertigation frequency with 5 d promoted cotton growth and induced a significant increase in N accumulation and dry mass of hybrid cotton, but there were not statistically different between two fertigation frequency treatments for 450 kg·hm^-2 of N level. It is recommended that increasing fertigation frequency could enhance yield of hybrid cotton in critical period of water and nutrition supply.The suitable irrigation water rate of hybrid cotton is from 500 to 520 mm, N rate is 300-360 kg·hm^-2, and the fertigation frequency should keep at 5 d in critical period of water and nutrition supply under this study conditions.