Bean and rice efficiency on soil p uptake evaluated by root architecture and p isotope technique

Abstract

The low availability of phosphorus in soil is a major constraint to the optimal development of plants in tropical regions. Many studies have demonstrated the need to improve the use of P fertilizer. Plants adapted to soils with low P concentrations tend to develop more effective mechanisms of roots exploration, increasing the length and density. Thus, the objective of this work is to evaluate the influence of the architecture of rice and bean crop roots related to the efficiency of P uptake in Cerrado soils, seeking to improve the capacity of the plant to absorb P in tropical soils. This project will be developed in three phases, I and III in the greenhouse, and II in field conditions in Brazil and a greenhouse experiment in USA. All procedures will be adopted for each phase equally for the two crops. The Phase I experiments will be conducted with the objective to select among 20 cultivars of upland rice and 20 cultivars of beans, the efficient ones to absorb P, using the 32P isotope dilution technique. The Phase II experiments will evaluate and characterize root architecture of selected10 cultivars of rice and 10 cultivars of bean and calculate the nutritional efficiency of these cultivars. Based on the results of the experiments of Phases I and II the phase III experiments will be carried out with the objective to verfy if the availability of P stimulates the modification of root architecture along the soil profile, by double labelling of the soil profile with radioisotope 32P and 33P. In Roots Lab at Pennsylvania State University, PA, USA, a completely randomized design greenhouse experiment will be carried out, with two phosphorus levels: low and high. Cultivars of bean with contrasting basal root whorl number (BRWN) selected in USA will be used to compare the differences in plant performance as affected with variation in BRWN. (AU)