Modeling of plant adaptation to climatic drought induced water deficit

Abstract

Soil moisture flux to root surface is considered the main determining factor of the transpiration intensity of plants. This assumption is valid not only in optimal plant physiological conditions without any physical barrier for the evaporation from the leaves, but in climatic drought as well, when high usable soil water amount cannot supply the evapo-transpiration intensity of plant. A new algorithm we built up describing the plant adaptation in climatic drought when stoma’s closure and reduction of plant’s potential evapo-transpiration (PET) starts. The adaptation algorithm of Doorenbos et al. (1978) is developed further defining that soil moisture content initiating the stomata’s closure. The critical soil moisture content is varying according to the PET, and drought tolerance of plant. If soil moisture content is less than the critical one, the plant evapo-transpiration (ET) can be highly different in the drought tolerance plant groups. The new drought tolerance algorithm is applied to maize field plots on chernozem soil of the experimental station of the Debrecen University, in East Hungary. Simulated soil water storages are compared to measured ones of a field plot treatment in five consecutive years. The soil moisture content profiles are measured with a BR-150 capacitance probe (Andrén et al. 1991). Differences between measured and simulated soil water storages are not significant in 2003. Simulations indicate low soil water storages in autumn of 2006, and in the first half of 2007 predicting the low maize production realized in 2007. The new plant adaptation algorithm can be used for a climate and soil moisture content sensitive irrigation control as well. The maize production is an illustrative biohydrological example of water flow through the soil-plant-atmosphere continuum.