EFFECTS OF DRIP IRRIGATION REGIMES UNDER PLASTIC FILM ON SUGAR BEET YIELD AND WATER USE EFFICIENCY IN XINJIANG

This 2-yr study analyzed the effects of different irrigation regimes of drip irrigation under plastic film on sugar beet production in Xinjiang, China, and established a binary quadratic regression equation and normalization to describe the maximum root yield, sugar yield, and water use efficiency. Three irrigation frequencies (10, 11, and 12 d) and two irrigation water quotas (45 and 60 mm) were combined to form six treatments. Irrigation frequency had a significant effect on root yield at 1% level of significance in both years, but the effects on sugar yield and water use efficiency were nonsignificant. In both years, the sugar yield resulting from 60 mm irrigation water quota at frequency of 11 d increased by 10.8% and 6.5%, respectively, compared with that resulting from 45 mm irrigation water quota at frequency of 11 d. The regression equation based on the experimental observations indicated that in Xinjiang the optimal irrigation regime was 11 d and 55 mm which saved 21.2% irrigation water for the highest sugar beet yield. The data optimization to determine the weight of roots and evapotranspiration found that root growth exhibited a pattern similar to the aboveground crop growth, and the root growth was most rapid in the period 30 July to 10 August.