滴灌技术参数对南疆棉花生长和土壤水盐的影响.

An optimal irrigation management needs to clarify the effects of technical parameters on the crop growth, dry matter accumulation, seed yield, and the distribution of water and salt in soil. In this study, a two-year field experiment was conducted from April to October in 2018 and 2019, to investigate the effects of various amount of drip irrigation and emitter discharge rate on cotton growth at the 31st Regiment in Korla of Southern Xinjiang (86°56′58″E, 40°53′03″N). Three levels of drip irrigation were designed, including the full irrigation (W3:100% ETc, ETc is the crop evapotranspiration), moderate irrigation (W2:80% ETc), and low irrigation (W1:60% ETc). Two of emitter discharge rate (1.8 and 2.4 L/h) were applied to explore the optimal combination of drip irrigation amount and emitter discharge rate for cotton production, resulting in a total of six treatments with three replicates. Cotton growth indexes were measured, including the yield and its components, soil water moisture, and soil salinity. The main results were as follows: 1) There were significant effects of irrigation amount and emitter discharge rate on plant height, stem diameter, leaf area index, dry matter accumulation, yield and its components. In the bolling opening stage of 2018 and 2019, the plant height in the W1 treatment decreased by 10.40% and 11.22%, compared with that in the W3, respectively. The leaf area index in the W1 treatment was 22.52% and 44.16% lower than that in the W3. The plant height in the W1 treatment was 11.38% and 4.64% lower than that in the W3, when the emitter discharge rate was D2.4. The leaf area index in the W1 treatment was 24.55% and 53.83% lower than that in the W3. At the same rate of emitter discharge, the growth indexes, yield and its components of cotton increased with the increase of irrigation amount. Specifically, the cotton growth indexes, seed cotton yield and its components of W3 were significantly higher than those of W1 and W2. Under the same irrigation amount, the plant height, stem diameter, leaf area index, dry matter accumulation, effective boll number, 100-boll weight, and seed cotton yield were higher at the emitter discharge rate of D2.4, compared with those of D1.8. In 2018 and 2019, the yields of three irrigations amount under D2.4 increased by 4.81%, 8.39%, 4.69% and 4.98%, 7.23% and 11.06%, compared with those under D1.8. The corresponding water use efficiency under D2.4 was 13.48%, 5.44%, 8.99% and 5.61%, 5.36%,0.84% higher than that under D1.8, respectively. 2) The water use efficiency and irrigation water use efficiency decreased with the increase of irrigation amount. In W1 treatment, there was significantly higher than those of other irrigation treatments, at the same emitter discharge rate. The water use efficiency and irrigation water use efficiency at the emitter discharge rate of D2.4 were significantly higher than those D1.8 under the same irrigation amount. 3) The irrigation amount and emitter discharge rate had significant effects on soil water content and salinity distribution. The soil water content in the W3 was higher than those of W1 and W2 at the same emitter discharge rate. The distribution of soil water content in the D2.4 was more uniform than that in the D1.8 under the same irrigation amount. In the salinity of 0-40 cm soil layer, a gradual accumulation trend occurred during the whole growing season of cotton. The soil salinity decreased with the increase of irrigation amount at the same emitter discharge rate. The soil salinity in the D2.4 was lower than that of D1.8. When the irrigation amount was 100% ETc and the emitter discharge rate was D2.4, the soil water content was higher, the horizontal distribution of soil profile was more uniform, and the soil salinity was lower, indicating an optimal combination of parameters for the cotton growth. These results demonstrate that the irrigation amount of W3 (100%ETc) combined with emitter discharge rate of 2.4 L/h can be the optimal irrigation strategy for the cotton production in Southern Xinjaing, with the highest seed cotton yield of 7361.44 kg/hm2 in 2018, and 7837.91 kg/hm² in 2019, respectively. This finding can provide a theoretical basis to guide the efficient cotton production with water saving and salt control in the Korla region of Southern Xinjiang, China. [ABSTRACT FROM AUTHOR]