title: Genetic and agronomic assessment of cob traits in corn under low and normal nitrogen management conditions.
abstract: Exploring and understanding the genetic basis of cob biomass in relation to grain yield under varying nitrogen management regimes will help breeders to develop dual-purpose maize. With rising energy demands and costs for fossil fuels, alternative energy from renewable sources such as maize cobs will become competitive. Maize cobs have beneficial characteristics for utilization as feedstock including compact tissue, high cellulose content, and low ash and nitrogen content. Nitrogen is quantitatively the most important nutrient for plant growth. However, the influence of nitrogen fertilization on maize cob production is unclear. In this study, quantitative trait loci (QTL) have been analyzed for cob morphological traits such as cob weight, volume, length, diameter and cob tissue density, and grain yield under normal and low nitrogen regimes. 213 doubled-haploid lines of the intermated B73 × Mo17 (IBM) Syn10 population have been resequenced for 8575 bins, based on SNP markers. A total of 138 QTL were found for six traits across six trials using composite interval mapping with ten cofactors and empirical comparison-wise thresholds (P = 0.001). Despite moderate to high repeatabilities across trials, few QTL were consistent across trials and overall levels of explained phenotypic variance were lower than expected some of the cob trait × trial combinations (R (2) = 7.3-43.1 %). Variation for cob traits was less affected by nitrogen conditions than by grain yield. Thus, the economics of cob usage under low nitrogen regimes is promising.
authors.affiliation: Department of Agronomy, Iowa State University, Ames, IA, 50011, USA.
authors.forename: Constantin
authors.initials: C
authors.lastname: Jansen
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hongjun
authors.initials: H
authors.lastname: Liu
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Gonzalez-Portilla
authors.forename: Nick
authors.initials: N
authors.lastname: Lauter
authors.forename: Bharath
authors.initials: B
authors.lastname: Kumar
authors.forename: Ignacio
authors.initials: I
authors.lastname: Trucillo-Silva
authors.forename: Juan Pablo San
authors.initials: JP
authors.lastname: Martin
authors.forename: Michael
authors.initials: M
authors.lastname: Lee
authors.forename: Kevin
authors.initials: K
authors.lastname: Simcox
authors.forename: Jeff
authors.initials: J
authors.lastname: Schussler
authors.forename: Kanwarpal
authors.initials: K
authors.lastname: Dhugga
authors.forename: Thomas
authors.initials: T
authors.lastname: Lübberstedt
mesh_terms: D056804:Biofuels; D018533:Biomass; D002874:Chromosome Mapping; D005819:Genetic Markers; D005838:Genotype; D006238:Haploidy; D009584:Nitrogen / Q000378:metabolism*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D003313:Zea mays / Q000235:genetics* / Q000502:physiology
chemical_list: D056804:Biofuels; D005819:Genetic Markers; D009584:Nitrogen