Predicting the effects of soil water content and soil water potential on transpiration of maize

An improved steady-state soil-vegetation-atmosphere transfer model was applied to three types of soils (loess, loamy soil, and sandy soil) and three typical daily meteorological conditions (a sunny day, a cloudy day, and an overcast day) to calculate the relationships between maize transpiration rates and an average soil water content or soil water potential. The model proposed can simulate the soil-plant-atmosphere continuum allowing to express soil, plant and atmospheric properties in detail, and thus, calculate the relationship between transpiration rate and average soil water content or soil water potential in the root zone. Atmospheric factors strongly affected the ratio between the actual and potential transpiration (relative transpiration) in conditions of the water stress. On the other hand, when the soil water content was sufficiently high, the relative transpiration was practically independent of atmospheric factors. The simulated relationships between transpiration of maize, soil water content and soil water potential were found to be in a good agreement with measured data.