Nitrogen Use Efficiency and the Genetic Variation of Maize Expired Plant Variety Protection Germplasm

Abstract

Nitrogen use efficiency (NUE) in maize (Zea mays L.) is an important trait to optimize yield with minimal input of nitrogen (N) fertilizer. Expired Plant Variety Protection (ex-PVP) Act-certified germplasm may be an important genetic resource for public breeding sectors. The objectives of this research were to evaluate the genetic variation of N-use traits and to characterize maize ex-PVP inbreds that are adapted to the U.S. Corn Belt for NUE performance. Eighty-nine ex-PVP inbreds (36 stiff stalk synthetic (SSS), and 53 non-stiff stalk synthetic (NSSS)) were genotyped using 26,769 single-nucleotide polymorphisms, then 263 single-cross maize hybrids derived from these inbreds were grown in eight environments from 2011 to 2015 at two N fertilizer rates (0 and 252 kg N ha −1 ) and three replications. Genetic utilization of inherent soil nitrogen and the yield response to N fertilizer were stable across environments and were highly correlated with yield under low and high N conditions, respectively. Cluster analysis identified inbreds with desirable NUE performance. However, only one inbred (PHK56) was ranked in the top 10% for yield under both N-stress and high N conditions. Broad-sense heritability across 12 different N-use traits varied from 0.11 to 0.77, but was not associated with breeding value accuracy. Nitrogen-stress tolerance was negatively correlated with the yield increase from N fertilizer.

Plant Nutrient Dynamics in Stressful Environments: Needs Interfere with Burdens

“…The elucidation of relevant genes and of genetic potentials are an important basis for breeding crop varieties with improved performance in stressful environments [31][32][33][34][35]. Besides traditional breeding programs, new tools to improve stress responses became available over recent decades, and may allow more direct genetic improvements to be made.…”

“…Mastrodomenico et al [31] started a research program in the corn belt based on old maize varieties (expired plant variety protection germplasm) and aimed at identifying possibilities of improving the performance under nitrogen stress (poor nitrogen availability). The paper is based on data from field experiments from four years at eight locations.…”

Genomic Selection Using Maize Ex‐Plant Variety Protection Germplasm for the Prediction of Nitrogen‐Use Traits

“…A recent study evaluating the genetic variation for NUE in the US maize germplasm found a large range of broad-sense heritability estimates (from 0.11 to 0.77) across 12 N-use traits described in Table 1 (Mastrodomenico et al, 2018). This study suggested that breeding for improved NUE will require an integration between selection of highly heritable secondary traits, such as grain protein concentration or harvest index at high N, and marker-assisted breeding.…”

“…Previous research has demonstrated that maize genotypes can reach high NUE using different plant physiological strategies (Mastrodomenico et al, 2018). Previous research has demonstrated that maize genotypes can reach high NUE using different plant physiological strategies (Mastrodomenico et al, 2018).…”

“…Nitrogen use efficiency is the product of N uptake efficiency (NUpE, the ratio of the additional plant N content due to fertilizer N to the amount of fertilizer-applied N) and N utilization efficiency (NUtE, the ratio of yield increase to the difference in plant N content compared with those of an unfertilized crop) (Moll et al, 1982). Therefore, NUpE and NUtE are important component traits for the genetic characterization of maize NUE (Uribelarrea et al, 2007;Haegele et al, 2013;Mastrodomenico et al, 2018). In addition, secondary traits relevant for NUE improvement include harvest index, grain protein concentration, and genetic utilization (GU) (Haegele et al, 2013).…”