title: Variation in nitrogen use efficiency among soft red winter wheat genotypes.
abstract: Nitrogen use efficiency (NUE), defined as grain dry weight or grain nitrogen as a function of N supply, was evaluated in 25 soft red winter wheat genotypes for two years at one location. Significant genotypic variation was observed for NUE, nitrogen harvest index, and grain yield. Genotype x environment interaction for these traits was not significant. Several variables including N uptake efficiency (total plant N as a function of N supply), grain harvest index, and N concentration at maturity were evaluated for their role in determining differences in NUE. Nitrogen uptake efficiency accounted for 54% of the genotypic variation in NUE for yield and 72% of the genotypic variation in NUE for protein. A path coefficient analysis revealed that the direct effect of uptake efficiency on NUE was high relative to indirect effects.
authors.affiliation: Department of Agronomy, University of Kentucky, 40546-0091, Lexington, KY, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Van Sanford
authors.forename: C T
authors.initials: CT
authors.lastname: Mackown