关键词: 西瓜, 砾石覆盖, 土壤蒸发, 蒸散

Abstract: We conducted trial to study the moisture storage effect of gravel mulch with different grain size on watermelon field in the Loess Plateau of northwest China in 2004. The trial involved four levels of gravel and sand diameter: 2~5 mm(A), 5~20 mm(B), 20~60 mm(C) and no gravel and sand mulching (control). All of treatments were randomized with three replications. There was a significant difference in evapotranspiration and evaporation amounts among treatments. The treatment A had significantly less evapotranspiration than B and C, however, it was not significantly different to the control. Evaporation and its ratio in evapotranspiration increased with gravel diameter increasing. So mulching with gravel-sand could decrease soil evaporation in watermelon field. The ratio of soil evaporation from evapotranspiration was 40.7% in the through growth period of watermelon for control, whereas it was only 17.8%~25% for treatments mulched with gravel-sand. For treatments mulched combination with gravel-sand and plastic film, the soil evaporation reduced by 78~93.7 mm in comparison with non-mulching, and 16.9~26.3 mm to mulching only with gravel-sand. The yield was not obviously different among treatments, but water use efficiency (WUE) significantly changed; it was much higher for treatment A than that for treatment C, but the soluble carbohydrate content lessened for smaller size gravel-sand mulching. The study proved that mulching with gravel-sand could increase yield, the soluble carbohydrate content and WUE. Proper diameter of gravel-sand was 5~20 mm.

Key words: watermelon(Citrullus lanatus), gravel-sand mulching, soil water, evaporation, evapotranspiration