Genetic variation among maize genotypes for phosphorus-uptake and phosphorus-use efficiency in nutrient solution

Parental genotypes and their derived hybrids of maize (Zea mays L.) were studied in nutrient solution for phosphorus (P)-uptake and P-use efficiency under greenhouse conditions. In the first trial, three hybrids were evaluated: HS 1227, HS 7777 (simple-crosses), and HD 7974 (HS 1227 x HS 7777). In the second trial, four inbred lines [L4 and L40 (P-inefficient), L29 and L42 (P-efficient)], three Fl hybrids [(L29xL42), (L40xL4), (L4xL29)], and a commercial hybrid (AG 401), were tested. Plants were grown with 0.360 mmol P in 2.7 liter pots, up to 29 days (1st experiment) and 21 days of age (2nd experiment). Thereafter, plants were transferred to a P-free nutrient solutions for 24 hours, before three P levels were added(0.180, 0.360, and 0.720 mmol P). Phosphorus uptake rates (depletion) were determined under controlled conditions during 5.25 hours (1st experiment) and 3.5 hours (2nd experiment). Plants were also evaluated for shoot and root dry matter, root length, P content, P distribution, and P-use efficiency. Most the favorable characteristics for P uptake and use efficiency identified in some of the parental genotypes, in both experiments, were also found in the derived hybrids, indicating that the P-efficiency characters studied might be heritable and under genetic control.