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CROP BREEDING & GENETICS

Estimating the Proportion of Nitrogen Remobilization and of Postsilking Nitrogen Uptake Allocated to Maize Kernels by Nitrogen-15 Labeling

^a Station de Génétique Végétale, INRA-UPS-INAPG-CNRS, Ferme du Moulon, 91190 Gif/Yvette, France
^b Unité de Nutrition Azotée des Plantes, INRA route de St Cyr, 78026 Versailles Cedex, France
^c UMR INRA-USTL Stress abiotiques et différenciation des végétaux cultivés, Estrées-Mons, 80203 Péronne, France
^d Institut de Biotechnologie des Plantes, Université de Paris-Sud, 91405 Orsay Cedex, France

^* Corresponding author (gallais{at}moulon.inra.fr).

Estimating the proportion of N remobilization and postsilking N uptake allocated to kernels may help to improve N-use efficiency in maize (Zea mays L.). In this study, we show theoretically and experimentally, that ¹⁵N labeling at the beginning of stem elongation can be used in the field to estimate the proportion of N remobilized from the vegetative parts to the kernels of maize by measuring ¹⁵N distribution only at maturity. In the same way, ¹⁵N labeling at silking allows a determination of the proportion of postsilking N uptake allocated to the kernels by measuring ¹⁵N distribution only at maturity. Two 1-yr experiments with three and four genotypes and one 2-yr experiment with testcross progenies from 66 recombinant inbred lines were developed. Nitrogen-15 labeling during vegetative growth provided an estimate of the proportion of N remobilized with a greater accuracy compared with the "balance" method, which computes the difference between the amount of N present in the stover at silking and the amount of N present in the stover at maturity. The validity of our ¹⁵N method is mainly based on the assumption that less than 15 to 20% of ¹⁵N is taken up after silking. The determination of the proportion of postsilking N uptake allocated to kernels requires assumptions that are more difficult to fulfill. Nitrogen-15 labeling in the field at the beginning of rapid stem growth appears to be a useful tool for studying the genetic variability of N remobilization using a large number of genotypes.

Abbreviations: NHI, nitrogen harvest index • RIL, recombinant inbred lines • RSA, relative specific allocation

This article has been cited by other articles:

				M. Coque and A. Gallais Genetic Variation for Nitrogen Remobilization and Postsilking Nitrogen Uptake in Maize Recombinant Inbred Lines: Heritabilities and Correlations among Traits Crop Sci., September 1, 2007; 47(5): 1787 - 1796. [Abstract] [Full Text] [PDF]