冬小麦、夏玉米叶水势、蒸腾和液态水流阻力的田间试验研究

FIELD RESEARCHES ON WATER POTENTIAL, TRANSPIRATION AND RESISTANCE TO WATER FLOW FOR WHEAT AND MAIZE

根据对冬小麦、夏玉米生长期间的叶水势、蒸散、棵间蒸发、土壤含水量等要素日变化过程的测定，计算了土壤－植物－大气系统水从土至叶片的液态水传输阻力和其日变化过程，结果表明，随着蒸腾强度的增加，液态水流阻力呈非线性的递减状态。通过分析液态水流阻力的组成和各成分对蒸腾的影响，提出了减少根系吸水阻力。

Measurements of leaf water potential, evapotranspirtaion and soil evaporation rate, stomatal resistance and soil water contents were made for winter wheat and maize under sufficient water supply conditions in 1995 and 1996. The plant resistance to liquid water flow and its relationship with transpiration rate were calculated and evaluated. The results showed that the resistance was decreasing non linearly with the rising of transpiration rate. The resistance to liquid water flow in winter wheat is higher than that in maize, and also the stomatal resistance of winter wheat is lower, so the plant water condition of maize is more favorable for crop growth than that of wheat, which may be one of the reasons that water use efficiency of maize is higher than that of wheat. For the components of the resistance to liquid water flow, the resistance of root in it plays an important role. Then how to reduce the resistance in root water uptake is a key factors in increasing soil water utilization by plants. Ways for reducing this resistance include: increasing root length density and depth in soil by measures such as modification of soil conditions, water supply patterns and fertilizers; reducing the “junction resistance” to water flow in root systems by breeding new varieties and etc..