Water Use Efficiency of Field-grown Maize during Moisture Stress

摘要

Theoretical analysis of the CO2 assimilation and water loss by single leaves suggests that the water use efficiency of C4 species decreases as stomatal resistance increases. To confirm this hypothesis for a complete maize crop, results from computer simulations and a field experiment were compiled for varying stomatal resistances. A soil-plant-atmosphere model allowed simulations of the many simultaneous interactions between a crop canopy and its environment. The simulations for varying stomatal resistances clearly indicated that as stomatal resistance increased, water use efficiency of the maize crop decreased. The field experiment data also confirmed that water use efficiency was significantly decreased under water stress conditions when stomatal resistance increased. We concluded that management practices for maize, which induce moisture stress conditions resulting in increased stomatal resistance, reduce both crop photosynthetic productivity and water use efficiency.