封丘地区土壤水分平衡研究 Ⅳ.雨养条件下三个不同湿度麦季的小麦耗水量与水分利用率

根据水量平衡方程式计算,雨养麦田三个试验麦季的耗水量分别为435.5、326和293.8mm,它们可代表该区过湿、一般和干旱年分的小麦耗水量.小麦地上部分生物量(茎杆+籽实)与其耗水量成正比,以第一麦季为100,第二、第三麦季分别为85和70;但籽实产量的反应与地上部生物量的反应并不一致,它们分别为100、102、70,以第二麦季最高.由于该麦季的耗水量相对较少,故有很高的水分利用率(1.73×10^-3kg/1)为华北地区所罕见.在耗水量中,土嚷储水的贡献约占50%.在降雨少而土壤储水丰足的年份,其贡献高达60%,是小麦水分的重要来源.在充分施肥条件下,小麦的水分利用率≥1.26×10^-3kg/1,它是建立预测小麦产量的经验模型的重要参数.

RESEARCH ON SOIL WATER BALANCE IN FENGQIU REGION IV. WATER CONSUMPTION AND WATER USE EFFICIENCY OF RAINFED WHEAT FIELD UNDER DIFFERENT HYDROLOGICAL CONDFTIONS IN THREE EXPERIMENTAL SEASONS

In accordance with the calculation of water balance equation, the amounts of water consumed in a rainfed wheat field in three experimental seasons were 435.5, 326.0 and 293.8 mm respectively. These results can represent the water consumption under the hydcological condition in excessive, moderate and defective levels respectively in this region. The biomass yield (grain-J-straw) of the wheat was proportional to the water consumption. To take the biomass of the first experimental season a,s the index of 100, the biomass yields of the second and of the third were 85 and 70 respectively. But the response of the grain yield was not identical to the that of tht biomass. They were 100, 102 and 70 respectively in which the highest one was found in the second experimental season. Because the amount of water consumed in this season was relatively low that the water use efficiency was very high (1.73×10^-3kg/l) which was excellent in North China. About 50%; of the total amount of water consumed came froth the water stored in soil before sowing. In the year less in rain fall during the growing season but abundant in water stored in soil, this percentage would be up to 60% showing that soil water is an important water source for wheat growth. lJnder optimum fertilizing conditions, the water use efficiency of wheat was more than 1.26×10^-3kg/1 which was an important parameter for the development of empirical model used to predict wheat yield.