Long-term trends and genetic architecture of seed characteristics,grain yield and correlated agronomic traits in triticale (×Triticosecale Wittmack)

The aim of this study was to investigate long-term genetic trends and the genetic architecture of grain yield, seed characteristics and correlated agronomic traits in triticale. Therefore, a panel of 846 diverse triticale genotypes was assessed for three agronomic and three seed shape- and size-related traits. We observed a high genotypic variation and a high heritability for all traits. Analysing the development of these traits during the last decades revealed a continuous increase for grain yield and thousand-kernel weight, and a slight increase in seed width. The seed characteristics and thousand-kernel weight formed a complex of highly positive correlated traits. Genome-wide association mapping revealed many small-effect QTL and a few moderate-effect QTL. The allele frequencies of the moderate-effect QTL followed the same temporal trends as observed for the phenotype. In line with the phenotypic correlations, we identified several pleiotropic QTL for grain yield, thousand-kernel weight, seed width and seed area. Our results illustrate the continuous progress achieved in triticale breeding and suggest that triticale seeds have been selected to be more spherical in modern cultivars.