MODELING THE BRANCHING GROWTH FRACTAL PATTERN OF THE MAIZE ROOT-SYSTEM

Using the technique of L-systems, a growth model of the maize root sys tem is developed. From the observation of the root systems developed u nder various soil density in eight root boxes, a spatial hierarchy of growth rules was extracted. The rules were divided into three categori es: a meta-rule for describing features of an entire root system, a br anching growth rule and a tip elongation rule. Some variations in the entire features of the root system, such as the outline and the root d istribution, were confirmed by observation, and then the respective me ta-rules were re-defined. The branching properties of first- and secon d-order lateral roots were statistically almost equal in the observati ons, and this lead us to set up a single stochastic branching growth r ule. Tip elongation movement was not observed here; its rule had to be assumed by reference to data in the literature. A single set of branc hing growth and tip elongation rules were coupled with the respective meta-rules corresponding to the root samples observed, where a small s cale rule was loosely governed by a large scale rule. Computer simulat ions offered optimized drawings of the observed root systems, and they also reproduced a typical anisotropic power distribution of roots sim ilar to those observed.