Plant water balance—its relationship to atmospheric and edaphic conditions

Abstract

An adaptation of Van den Honert's model of the soil—plant—atmosphere continuum is useful for understanding how leaf water potential is influenced by soil and atmospheric factors in the complex natural environment. In field-grown citrus, climatic and leaf resistance changes causing increased transpiration rates resulted in reduced leaf water potentials; however, the relationship between leaf water potential and transpiration was influenced by soil water potential and soil temperature, as predicted by the model adaptation. Leaf water potentials of young greenhouse-grown sunflower and sesame plants remained constant and high over a broad range of transpiration rates, suggesting a much more efficient water transport system for these plants. The comparison of the relationship between plant water balance and transpirational flux for contrasting species and environments is a promising approach for understanding the suitability of crop plants for their environment.