Genotypic Differences in Nitrate Absorption and Partitioning of N Among Plant Parts in Maize¹

Abstract

The objectives of this study were to compare corn ( Zea mays L.) inbreds and their F 1 hybrids with respect to pattern of nitrate (NO 3 − ) uptake during the growth period and partitioning of absorbed N among plant parts. A four‐parent (‘W64A’, ‘WI82E’, ‘A632’, ‘Oh43’), half‐diallel of corn was used. Disappearance of NO 3 − from solution culture was monitored from 10 days after emergence until 20 days after silking. Plants were then harvested and the distribution of total N, NO 3 − , and reduced N (RN) among leaf blades, leaf sheaths, stems, ears, and roots was determined. Significant differences in NO 3 − uptake per plant were found among the 10 genotypes, but there was no relationship between NO 3 − removed by F 1 hybrids and that removed by their inbred parents. Genotypic differences in dry weight, NO 3 − and RN per plant, and NO 3 − and RN còncentrations were found in all plant parts. Inbreds W64A and WI82E were especially high in NO 3 − and RN. Dry weight and NO 3 − in all plant parts, and RN in all plant parts except ears, were usually greater in hybrids than in inbreds. In general, stem NO 3 − concentration of the F 1 approximated the mid‐parent mean. Concentration of NO 3 − in other plant parts of F 1 hybrids was not related to that of their parents. No relationship between parents and progeny in RN concentration was found in any plant part. In this study, genetic variation in NO 3 − uptake and partitioning of absorbed N was demonstrated. This variation suggests the potential for genetic improvement of NO 3 − uptake and N utilization by corn.