A methodology was defined, using nutrient solution as growth medium, to evaluate and select more efficient corn (Zea mays L.) inbred lines in regard to P uptake and use, under low P conditions. Plants of 40 corn inbred lines were allowed to grow in nutrient solutions for 20 days, with 6.0 mg P/2.8 liters and continuous aeration, without renewing the solution until P-deficiency symptoms appeared. Differential top and root growth was observed among inbred lines. Plants differed with respect to dry matter weight, plant height, total P content and dry matter produced per unit P absorbed (efficiency ratios). The variation found for whole plant P content followed, proportionally, the variation observed for dry matter weight. The relation ship between plant growth and efficiency ratio was less evident, indicating that differentes in dry matter weight were mostly due to the differential P uptake rather than to the P use mechanism. The genetic materials were then classified based on the total dry matter weight means, which were fitted by a Student's t distribution. The confidence interval for this distribution, calculated with 99.9% probability, allowed to separate 9 P-efficient inbred lines (total dry weight above 6.04 g), 11 P-inefficient inbred lines (total dry weight below 5.28 g) and 20 intermediary lines (total dry weight between 5.28 and 6.04 g).
phosphorus; corn; P uptake efficiency; inbred line selection; P utilization efficiency; nutrient solution