Hormone-dependent model on seed germination sensitive to growth stage

In the germination of seeds, there often observes cluster-formation of well-grown roots and the edge effect phenomenon. During germination and growth before starting photosynthesis, direct interaction such as competition for nutrition among hosts is rather weak because of self-supplying of nutrition. Instead, hormones play an important role and may cause the above experimental observations. In order to understand these aspects, we propose a growth model for root. The hormone effect and its growth-stage-dependent sensitivity are taken into consideration. It is discussed how the growth process of grouping roots is influenced by exogenous hormones secreted from roots.