Abstract:

Crop coefficient-reference crop evapotranspiration method is a popular method to calculate water requirement of crop. As an important parameter for this method, ascertained crop coefficient has become a key issue to study water requirement of crop. According to the field experiments from 2005 to 2007, reference crop evapotranspiration in Guanzhong region was calculated by using Penman-Monteith equation and actual crop evapotranspiration was achieved by water balance equation and adjustment coefficient of soil water. Crop coefficients of soybean in different stages were calculated based on the above results. Variations of crop coefficient were also analyzed. The results indicated that average reference crop evapotranspiration during crop growing stage in Guanzhong region is 498.4 mm. Average crop coefficient for the whole growing period is 0.89. The highest value 1.26 occured at the stage from flowering to fructification, followed by the stage from fructification to maturity with the average value of 1.04 and the lowest value 0.29 is at the stage between seeding to seedling. Under the climate background of Guanzhong region, there is a better relationship among soybean crop coefficient and cumulative temperature above 10℃.

Key words: soybean, crop coefficient, reference crop evapotranspiration

摘要：

作物系数-参考作物蒸发蒸腾量法是作物需水量计算最普遍采用的方法。作物系数作为该方法的重要参数,它的确定已成为作物需水量研究的关键问题。依据2005-2007年3年田间试验资料,利用Penman-Monteith公式计算了关中地区大豆全生育期间参考作物蒸散量,并利用农田水量平衡方程及土壤水分胁迫系数计算了作物实际蒸发蒸腾量,由此计算了大豆各生育阶段的作物系数,并分析了大豆作物系数变化规律。结果表明:关中地区大豆全生育期间参考作物蒸散量平均为498.4 mm;大豆作物系数全生育期平均为0.89,在开花~结荚阶段最大,平均为1.26,其次为结荚~成熟阶段,平均为1.04,播种~幼苗阶段最小,为0.29;在关中气候背景下,大豆作物系数与>10℃积温具有较好的二次多项式关系。

关键词: 大豆;作物系数;参考作物蒸发蒸腾量