Nitrate Uptake and Partitioning by Corn {Zea maysL.) Root Systems and Associated Morphological Differences among Genotypes and Stages of Root Development

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Abstract
Pan, W. L., Jackson, W. A. and Moll, R. H. 1985. Nitrate uptake and partitioning by corn (Zea mays L.) root systems and associated morphological differences among genotypes and stages of root development.—J. exp. Bot, 36: 1341–1351 Nitrate uptake and partitioning by root systems of corn inbred lines were examined. Six-day-old root systems of decapitated seedlings of seven corn inbred lines were shown to differ markedly in their capacity for nitrate uptake and partitioning. The magnitude of nitrate uptake ranged from 44–86 μmol NO−3 g −1 fr. wt. during an 8 h period. Relative nitrate translocation (% of total uptake) also varied among the seven genotypes from 4–25%, and differences in the proportions accumulated (28–73%) and reduced (22–58%) were observed. Three of these genotypes were then examined at 5,6, and 8 d after germination to determine the effect of lateral root proliferation on the previously observed differences in nitrate uptake and partitioning. Nitrate translocation per unit mass increased with root elongation and lateral root proliferation, and genotypic differences in this partitioning process were associated with differences in these morphological parameters. In contrast, differences among genotypes in their capability to accumulate nitrate were not correlated with these differences in morphology. Evaluations of genotypic differences in nitrate uptake and partitioning at the seedling stage should include the rate and characteristics of morphological development