Mathematical Simulation of Rice Root Spatial Distribution and Its Application

To clarify the root spatial distribution characteristics of rice, root box experiments were conducted to collect root distribution data. The equation Y = α(1-b^X), where Y is the total root length, and X is the distance of root horizontal distribution or the depth of root vertical distribution, was used to establish root distribution model. Moreover, influences of water management on root growth and distribution were analyzed using the model. The results showed that about 88% of roots were distributed in the top 10 cm soil layer, and 60%-70% of the roots were distributed in horizontal range of 10 cm from the plant at tillering and ripening stages. The change in total root length with the distance of root horizontal distribution or the depth of root vertical distribution could be simulated by the equation Y = α(1-b^X). Water management had impact on rice root vertical distribution and root number without affecting the root horizontal distribution. The rice roots were 0.6 and 3.5 cm deeper, 19.8% and 26.4% longer, and 28.3% and 21.0% greater in number under intermittently flooded irrigation compared with wet irrigation and continuously flooded irrigation, respectively. The variation of average angle of roots showed similar tendency.