Coupling effects of water and nitrogen on cotton growth and yield under mulched drip irrigation with different qualities ofwater in the arid region

摘要

Water quality is an important factor influencing the dynamics of water and fertilizer in soil and crop growth. To investigate the coupling effect of the water and fertilizer on cotton growth and yield under mulched drip irrigation using different qualities of water, the field plot experiment was conducted in the arid region of southern Xinjiang during the 2018 growing season of cotton. Treatments included three irrigation levels (II, 12 and 13; irrigation at 125%, 100% and 75% of crop water requirement), three nitrogen application rates (Fl, 315 kg/ha; F2, 255 kg/ha; F3,195 kg/ha), and two water qualities (G, ground water, 1.27g/l; S, brackish water, 3 g/l). Results showed that irrigation amount and irrigation water quality had a significant impacton leaf area index (LAI), plant height, yield, and water use efficiency of cotton. When ground water was used, LAI, plant height and yield of II and 12 treatments were significantly higher than those of 13 treatment by 26% and 17%, 8% and 4%, 30% and 17%, respectively, while the water use efficiency were 8% and 5% lower than that of 13. When brackish water was used, LAI, plant height and yield of 11 treatment were significantly higher than those of 13 treatment by 29%, 14%, and 12%, while the water useefficiency was 24% lower than that of 13. For a given irrigation amount, LAI, plant height, and yield of the ground water treatments were averagely 21%, 14% and 13% higher than those of brackish water treatments. Furthermore, no significant effect of nitrogen application rate was found on LAI, plant height, yield and water use efficiency of cotton. The yield and water use efficiency of F2 treatment were higher than those of Fl and F3 treatments by 10% and 11%, 10% and 7% under irrigation with ground water, respectively. Considering yield and water use efficiency, the combination of high irrigation amount and medium nitrogen application rate is appropriate for cotton irrigated with ground and brackish water in the arid region.