PLANT-GROWTH MODELING AND THE INTEGRATION OF SHOOT AND ROOT ACTIVITIES WITHOUT COMMUNICATING MESSENGERS - OPINION

In this paper, we consider the use of compartmental modelling to exami ne the integration of root and shoot resource allocation without the u se of partitioning functions or communicating messengers. Emphasing ov erall growth and the partitioning of biomass and resources between sho ots and roots, we discuss the use of modelling to explore mechanisms o f control, to direct experimentation and to test physiological hypothe ses concerning their regulation. We discuss how the interrelationships of allocation processes and growth might be considered by generating ''mutants'' of a basic model, and we suggest this approach as one gene ral way to increase interactions between modellers and experimentalist s.Recognizing that the meristematic origin of plant organs inherently limits the usefulness of two compartment (root and shoot) models, we c onsider three problems to be solved (both computationally and experime ntally) in extending modelling to more complex simulations: the incorp oration of direct root/shoot signaling for regulation of the shoot-sho ot ratio (S/R), the modelling of growth of individual leaves, and the definition of shoots based on component leaves and internodes. Finally , we briefly consider the problem of nitrogen and the regulation of S/ R as an example of experimentation directed by modelling.