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在黄土高原南部长武旱塬所做的田间试验结果表明 ,玉米的水分效应函数为 :Pw =1 .0 0 - 5.2 93( 1 -k) 2 .把式中k取为农田干湿指数 (旱作玉米全生育期内高肥水平下耗水量与需水量的比值 ) ,则Pw即为旱作玉米生产潜力指数 .试验中k值的表现区间为0 .78至 1 .1 0 ,k值的理论上界与局部农田潜在蒸散有关 .1 985～ 1 988年 ,旱作玉米的Pw的平均值为 0 .87.旱作玉米生产潜力的远期值与近期值变化趋势相似 ,前者 4年平均值为1 1 2 4 7kg·hm- 2 ,后者为 7696kg·hm- 2 .由于试区近年来物质能量向农田的不断强化投入以及对作物品种的改良 ,试区大田实际产量连年来向潜力值逼近 .
The results of field experiments in Changwu dry land of southern Loess Plateau show that the water effect function of corn is: Pw = 1 0 0 - 5.2 93 (1 -k) 2. Pw is the potential productivity index of dry-land corn in the experiment.The value of k in the experiment ranged from 0.78 to 1.10, k value The theoretical upper bound is related to the potential evapotranspiration of local farmland.180-1988, the average value of Pw of dry maize is 0.87.The long-term value of dry-land corn production potential is similar to that of the recent value, the former is 4 years The average value is 112447kg · hm-2 and the latter is 7696kg · hm-2. Due to the continual intensification of material energy to farmland and the improvement of crop varieties in recent years in the trial area, Potential value approximation.