The effect of different nitrogen doses and water levels on the yield and yield components of cotton

This study was conducted to determine the effect of irrigation levels and nitrogen doses on yield and some yield parameters of Stoneville 468 cotton (Gossypium hirsutum L.) cultivar produced in semi-arid climatic conditions in 2017 and 2018 crop growing seasons with 3 replications utilizing the split plot design with random blocks. Five fertilizer (nitrogen) doses (0, 100, 150, 200 and 250 kg ha(-1)) and 4 irrigation percentages (25, 50, 75% and 100% of the field capacity) were used as treatments. In the experiment, the main plots were nitrogen doses, and the sub-plots were amounts of irrigation levels. In the first year of the experiment, a total of 1258 mm irrigation water was applied to the 100% trial (I-100) while 1332 mm irrigation of water was applied. The results of study indicated that water stress caused a linear relationship between applied irrigation water amount and cotton seed yield, and the drip irrigation increased the nitrogen usage efficiency of the plants. As the amount of nitrogen rate and irrigation water applied was increased, plant height, the number of fruiting branches and bolls were increased. Whereas the amount of applied irrigation water, increased fiber length and the fiber length uniformity index but not fiber fineness according to the nitrogen dose application. Statistical analysis of water levels and nitrogen doses showed that 200 kg ha(-1) pure nitrogen and I-100 can be recommended.