控制灌溉条件下水稻蒸发蒸腾量及作物系数试验研究

根据国家“863”节水农业重大专项江西示范区晚稻节水灌溉试验资料,分析了控制灌溉条件下晚稻移栽后各周蒸发蒸腾量变化规律和影响因素,研究了控制灌溉条件下水稻作物系数的变化.研究结果表明:控制灌溉条件下水稻蒸发蒸腾在拔节孕穗期以及抽穗开花期保持较大值,其他时期则较小;蒸发蒸腾量与冠层净辐射量、饱和水汽压差等气象因素以及田间土壤水分状况关系密切,叶面积指数不是关键的影响因子;利用冠层净辐射量等气象因子及土壤水分系数表示的冠层阻抗与蒸发蒸腾量呈明显负相关关系;双季晚稻全生育期作物系数Kc平均值为1.27,生育中期的作物系数值稍大于FAO推荐参考值.

Experimental study on evapotranspiration and crop coefficient of rice under controlled irrigation

Based on experimental data about water-saving irrigation in a demonstration region for late rice planting in Jiangxi Province,an "863" national special project,the variation of weekly averaged evapotranspiration after transplanting and its influencing factors were analyzed under controlled irrigation,and the variation of crop coefficient was discussed as well.Some conclusions are drawn: evapotranspiration keeps high at shooting-booting stage and heading-flowering stage under controlled irrigation;soil-water condition and some meteorological factors,such as the canopy net radiation and saturation vapor pressure,rather than the index of leaf area,are the key factors affecting evapotranspiration;the canopy resistance obtained is negatively related to evapotranspiration; the mean value of crop coefficient for late rice in the whole growing season is 1.27,while in the middle period,it is a little higher than the reference values recommended by FAO.