作物水肥优化耦合区域的图形表达及其特征

Graphical Presentation and Their Characteristics of the Coupled Zones for Optimal Supplies of Water and Nutrients to Crops

用中国科学院安塞实验站田间试验数据 ,建立了水肥供应与玉米产量、耗水量的关系模型。以作物水分利用效率与产量为目标 ,得到了两类作物水肥优化耦合区域。在水肥坐标面上 ,取两种方向 (与产量达到最大的点的连线的方向及产量曲面的梯度方向 ) ,得到的水分生产弹性系数等于 1和等于 0的点所形成的区域均呈椭圆形 ,分别称为第一类椭圆和第二类椭圆。第二类椭圆与第一类椭圆相比 ,短轴缩小 ,长轴没有变化。最大产量与最大水分利用效率处于长轴的两个端点上。由此椭圆 ,根据节肥要求等条件 ,得到了水肥优化耦合区域。

The empirical functions of maize yield (Y) and water consumption (ET) under different regimes of water and fertilizer supplies were obtained from the field experimental data at Ansai Experimental Station of CAS. The coupled zones for optimal supplies of water and nutrients, for high yield and water use efficiency were identified through the established relationships. In the water and nutrient plain, the points for elasticity of water production (EWP) of 1 or 0 along two lines that leading to the maximum yield point and that of the yield gradient, formed two kinds of coupled zones of elliptical shape for optimal fertilizer and water supply, referred as the first and the second kind of ellipse, respectively. The minor axis of the second kind of ellipse is shorter than that of the first kind; however, the major axes are the same for two kinds of ellipse. And both Y max and WUE max were located at the ends of the major axes. Optimal supplies of water and fertilizer can be decided in the elliptical zone with additional considerations of other special requirements.