SPAC水分热力学函数及幼苗各叶位水分状况

1986～1987年在土壤-植物-大气连续系统(SPAC)中测定了土壤、小麦和玉米、大气的需水指标并计算了热力学函数。结果表明:SPAC中土壤水的偏摩尔自由能>植物水的偏摩尔自由能>大气水的偏摩尔自由能。大气水偏摩尔焓>土壤水偏摩尔焓>植物水偏摩尔焓。大气水的偏摩尔熵>土壤水的偏摩尔熵>植物水的偏摩尔熵。随着温度的升高,土壤水势、玉米小麦叶水势均升高,而大气水势降低。在SPAC中,玉米、小麦幼苗各叶位水势均表现为从基部向上依次增高的现象。

THE FUNCTIONS OF THERMODYNAMICS OF WATER IN SPAC AND WATER REGIME OF THE LEAVES IN DIFFERENT POSITIONS OF SEEDLINGS

The water requirement indices of soil, wheat and corn seedlings and atmosphere in a Soil-plant-Atmosphere Continuation(SPAC)were mesured and _ the thermodynamic functions of the components of this SPAC were also calculated in the years 1986-1987.It was shown that the partial molar free energy increased in the following orders.soil water>plant water>atmospheric water. The partial molar enthalpy of these components increased accoding to the order of atmospheric water>soil water>plant water.The partial molar entropy of these components also increased i'n'the following orders of atmospheric water >soil water>plant water. The water potential of soil, wheat and corn leaves rose, but atmospheric wateri> potential decreased as temperature increased, water potentials of the leaves in different positions of corn and wheat seedlings in SPAC appeared to increase from the base to the top of the plants in an orderly way.