Calculation of the Root/Shoot Ratio in the Models of Higher Plant Organogenesis

A new method for calculating the assimilate distribution between plant shoots and roots in dynamic models of production process for agricultural crops is suggested. The method is based on direct calculation of the dynamics of photosynthate accumulation and absorption rates of nitrogen compounds in the plant root system. The hypothesis underlying this method is that all mobile compounds entering the plant are completely utilized for the production of structured biomass. Unlike the method of distribution keys, which is widely used in similar models, the suggested procedure accounts for adaptive plant responses to both uncontrolled weather conditions and mineral nutrition. The suggested method was implemented as software within the framework of Agrotool (version 3) simulation system. Verification of the method in many years' field experiments with barley confirmed its efficiency and showed a satisfactory accuracy of model calculations.