| Abstract: | A three-dimensional model simulating the formation of root system architecture of maize was designed using object oriented programming (OOP) techniques. The model has been used to simulate the growth of roots in contrasting water profiles with or without gravitropism, and the mechanism of hydrotropism of root system and its relationship with gravitropism has been studied. In this model, the frontier of root system was treated as a population of root tips, each member of which responded individually to its local environment, and only a few of them could branch. The results of simulation showed that hydrotropism of maize roots could arise through the control of the elongation rate of single root by its local soil water potential. The difference in growth rate caused by the gradient of water potential along the soil profile alone could cause the root system as a whole to grow predominantly downwards, resulting in a shift of root distribution towards deeper layers. Gravitropism enhanced the downward predominance of the growth of root system, but the mechanism was different from that of hydrotropism. |
