Quantitative trait loci and environmental interactions associated with agronomic performance of wheat

In wheat, little information is available on the genetic components involved in grain yield and agronomic performance and how those components interact with different environmental conditions. This study had three objectives: (1) to identify regions of chromosome 3A containing quantitative trait loci (QTL) associated with agronomic traits in wheat, including anthesis date, plant height, grain volume weight, grain yield, 1000 kernel weight, spikes per square meter, kernels per spike, and kernels per square meter; (2) to identify and determine the type of environmental interactions of the detected QTLs, and (3) to examine the relationship between genotype × environment (GEI) and QTL × environment (QEI) interactions for agronomic traits using environmental covariates and molecular markers. A population of 98 chromosome 3A recombinant inbred chromosome lines (RICLs-3A) was evaluated in field trials in 1999 at Lincoln and in 2000 and 2001 in Lincoln, Mead, and Sidney using randomized complete block and incomplete block designs with four replications at each location. Twenty molecular markers were used to construct a genetic linkage map of chromosome 3A. QTLs and QEI were detected for each of the agronomic traits except anthesis data. QEI resulting from changes in magnitude were detected for grain yield and kernels per spike, and QEI resulting from crossover interactions for plant height and 1000 kernel weight. Individual environmental covariates explained 15–30% of the GEI detected for agronomic traits, while individual marker × environmental covariate interactions explained less than 3% of the GEI detected for agronomic traits. These analyses illustrated QTLs for agronomic performance traits can be detected on chromosome 3A that display environmental sensitivities attributed to temperature, precipitation, and solar radiation accumulation during the growing season. Grain yield performance and QTL expression were influenced most by differences in daily temperature and precipitation during pre-anthesis growth across environments, which corresponds to previous reports indicating temperature and water stress as the critical environmental factors determining grain yield for winter wheat in the Great Plains