Coupling effect of water and nitrogen of cotton under plastic mulching by drip irrigation

The coupling effect of water and nitrogen(N) of cotton under plastic mulching by drip irrigation was studied in Southern Xinjiang.The results showed that there existed a significant coupling effect between water and N.Water stress greatly inhibited N fertilizer effect,while there was a significant difference between cotton yields of treatment with different N application rate under appropriate irrigation.N fertilizer also promoted water effect;however,water is the main effect factor on cotton yield under plastic mulching by drip irrigation in Southern Xinjiang.Based on the results obtained in this experiment,the optimum combination of water and N was: the irrigation 505 mm and N 225 kg per hectare and the canopy indicators of high-yield cotton were: stem height 66.9 cm,leaf emergence 15.6,fruit branches 13.1 and number of bolls each plant 8.9,respectively.Water stress and N deficiency shorten development period of cotton,which maybe the main reason contributed to the yield difference between different treatments.