A functional-structural model for alfalfa that accurately integrates shoot and root growth and development

A model has been developed to quantify the organogenesis, structural dynamics, biomass production and allocation for alfalfa with shoots and roots. The basic units of development and growth were defined and symbolized into the Markov's states with a set of parameters describing the functions of the units. The Markov chain model was employed to describe the organogenesis and the topological structure controlled by the phenological schedules expressed by thermal time (°C·d). The biomass produced by the photosynthetic organs using the Gaussian integration method was allocated to each organ in terms of relative demand and its kinetical process expressed by uniformization expansion rate. And the geometry magnitude of each organ was calculated by the allometric relationships among dry biomass and geometry for each type organ over time. The model was parameterized and calibrated by two different experiments. The model successfully mimiced plant growth and development from structure and function and the comparisons among measured and simulated values were conducted for root and shoot system. The results show that the both had a good consistency and similar change trends. Finally, we discuss some problems and future research and application of the model.