Dynamics of rice root length and nutrient uptake and their simulation models

Water culture and field experiments were conducted to study the dynamoics of rice root growth and nutrient uptake. Root growth model, NPK in unit root surface area uptake velocity model and NPK cumulative uptake model were set up for rice in fitting its one growth period based on the improved relative modes for vegetable. In gernaeral, six root length growth models and eighteen NPK uptake velocity models and thirty-six NPK uptake dynamic models are all at the statistic significance levels. The results show that the dynamic characteristics of rice root length and NPK uptake present S type in one growth period, while NPK uptakes velocity on root surface increase rapidly in growth prophase and reach thier maximum values, and then have exponential decreases afterwards. The results of the water culture erperiment show that the times of maximum root length increased velocity and maximum root length are 68.85.4 days and 108.43.9 days respectively in 120 days growth period, and their differences are little among rice cultivars. The maximum root length increased velocity and maximum root length are 4531.51529.4 cm/( pot?d) and 2.89310.6237105 cm/pot respectively, and their differences are obvious among the cultivars. Field erperiments show that NPK uptake velocities in rice almost are in a similar trend under different fertilization treatments. NPK uptake velocities in rice reach their marximum values at 50th~60th day after the transplanting. But the marximum uptake capacities for NPK present near maturity. These results provide a scientical base for nutrient management in middle and anaphase of rice growth.