Selection of maize genotypes for phosphosrus efficiency

Abstract

The aim of this work was to understand and evaluate some of the process linked with the plant nutrient efficiency, especially that for phosphorus, in nutrient solution. There were evaluated twelve maize (Zea mays L.) hybrids; nine from the CNPMS breeding program and three comercial hybrids, grown in Steinberg's nutrient solution tested against four P concentrations (0.3; 0.9; 2.7 and 5.4 mg l^-1). Two experiments were then carried out: experiment 1; the nutrient solution was changed weekly and the plants harvested after 20 days growth, experiment 2; the nutrient solution was not changed and the harvest was realized as soon as the steady vegetative growth was reached. The dry weight of the shoot and roots were determined and analyzed for phosphorus. A significant difference among hybrids in P-efficiency utilization was observed. However these differences were basically due to the P concentration in the seeds rather than the genotypic variability and/or morphological, physiological and biochemistry differences in P-usage. Also the amounts of elements added somehow influenced the results. It was observed that the remaining seeds when removed from the seedlings did not overcome the seed effect. Hence, it is suggested that more efficient plant should be selected in field conditions, where a mature plant better caracterizes the nutrient efficiency.