土壤-植物-大气连续体水流阻力分布规律的研究

DISTRIBUTION OF HYDRAULIC RESISTANCE IN SOIL-PLANT-ATMOSPHERE CONTINUUM

本文依据田间实测资料,分析了土壤-植物-大气连续体水流阻力的相对重要性,结果表明在连续体中的水流阻力主要分布于从叶气孔腔到大气的扩散过程和根系的吸水过程。叶-气之间的水流阻力比土-根之间要大50倍。最后,讨论了控制连续体水流运动的气孔阻力的变化规律及其与环境因素之间的关系。

Based on the measured data of soil water potential,leaf water potential, air water potential,and transpiration rate in winter wheat and summer corn fields and the application of them to the Van den Honert (1948) steady-state flow equation,the magnitude, the variation with time and depth, and the relative importance of various resistences to water flow in soil-plant-atmosphere continuum (i.e.SPAC) were estimated.The estimated results indicated that the main resistances to water flow in SPAC take place in the two symmetrical connecting 'Chains' through which water enters the roots and emits out of the leaves of plants,the resis--tances from the leaves to atmosphere equal to 50 times that of soil-root system.So that the water flow in SPAC is controlled by leaf stomatal resistances and air boundary layer resistances.Discussed also were the leaf stomatal varing laws and the relationships between leaf stomatal and environmental factors, such as soil matric pcten-tial, air temperature, net radiation and air vapour pressure deficit.