旱坡地集水枣园的水量平衡研究

研究表明，黄土丘陵区旱坡地集水枣园的年降雨量达到331mm时，枣树生长期的水分供需在理论上达到平衡状态。降雨量低于331mm时，枣园水分出现亏损，水量平衡向负值倾斜。由于雨量分布不均，某一时期的早害会影响整个生育过程。实际观测表明，当集水枣园平均单株土壤水分净集水量达到树体蒸发量的2倍时，枣树才能正常地生长结果；而要达到这个集水量，枣园年降雨量需大于400mm。当降雨量为298mm时，枣树缺水随密度的加大而增加，4种密度缺水依次为－249．14kg、－354．56kg、－453．50kg和－640．95kg。

Water Balance in Water-collecting Jujube Garden of Arid Hillside Field

Study shows that when the annual precipitation reached 331 mm in water-collecting jujube garden of arid hillside field, the supply and requirement reached equilibrium theoretically, less than 331 mm, the garden showed water deficiency, and water balance inclined to negative. Because of the uneven distribution of precipitation, one period drought harmness would affect the whole process of growth and development, actual observation showed that when average water storage capacity of each plant in the soil reached twice of plant transpiration, the jujube plant could grow and fruit normally, however, if the soil would reach the water storage capacity, the annual precipitation should be more than 400 mm. When the annual precipitation was 298 mm, water deficiency of the jujube tree increased with the density, the water deficiencies of the soil at four kinds of densities were successively -249.14, -354.56, -453.50 and -640.95 kg.