Effect of Dripping Rate on Soil Water and Salt Redistribution and Growth and Yield of Watermelon in Gravel-mulched Field.

[Objective] Gravel mulching combined with drip irrigation is an improved agronomic technique for crop production in northwestern China. The purpose of this study is to investigate the impact of dripping rate of the emitters on soil water and salt redistribution, as well as the growth and yield of watermelon. [Method] The field experiment had three treatments with the dripping rate controlled at 2 L/h (Q1), 3 L/h (Q2), or 4 L/h (Q3), respectively. In each treatment, we measured the spatiotemporal variation in soil water and salt, water use efficiency, as well as growth, yield and fruit quality of the watermelon. [Result] Horizontal advancement of the wetting front in the soil increased with dripping rate. After harvest, soil salt content in the 0~100 cm soil layer decreased, with the decreasing rate increasing as the dripping rate increased. Also, with the increase in dripping rate, the soluble sugar content in the fruits increased first followed by a decline. Of the three dripping rates we compared, Q2 increased the soluble sugar content in the fruit the most, up by 54.3% and 22.3%, respectively, compared to Q1 and Q3. With the increase in dripping rate, the vitamin C content in the fruits decreased first and then ramped up. Q3 gave the highest vitamin C content, increasing by 53.7% compared to Q2. Increasing dripping rate boosted both fruit yield and water use efficiency. Compared to Q1 and Q2, Q3 increased fruit yield by 6.20% and 3.56%, and water use efficiency by 6.49% and 3.72%, respectively. [Conclusion] Taking soil water and salt redistribution, as well as watermelon yield and quality into account, the optimal dripping rate for watermelon growth in the gravel-mulched soil was 4 L/h when using the local saline water for irrigation. [ABSTRACT FROM AUTHOR]