Genetic parameter estimation for agronomic traits in grain-only and forage-plus-grain winter wheat systems

Dual purpose winter wheat utilized for both livestock forage and grain yield is frequently grown throughout the southern great plains of usa,yet no cultivars to date were bred specifically under a dual-purpose management system. this research was initiated to determine whether breeders should select winter wheat genotypes in a forage-plus-grain system,or continue the current practice of indirect selection in the grain-only system. thirty-seven random winter wheat lines were evaluated in three experiments for 3 yr at the north central research station,lahoma,ok. each experiment represented either an early-planted forage-plus-grain (fg) system,a normal-planted grain-only (go) system,or a forage-plus-grain control (fgc) system,in which the forage was not removed. to simulate continuous grazing,the fg experiments were mechanically clipped three to four times from november until first-hollowstem development in late-february. though significant genetic variation was observed among wheat lines for all traits under each system,the genotype × system interactions were not significant due to strong genetic (r g > 0.94) and phenotypic (r p > 0.71,p < 0.01) correlations. genetic variances and heritability estimates for all traits were equal to or slightly higher in the go system than those in fg and fgc systems. indirect selection in the go system was as effective as direct selection for trait improvement in the fg system. it is concluded that separate selection of wheat genotypes should not be applied in fg and go systems.