Cross prediction studies on spring barley : 2. Estimation of genetical and environmental control of yield and its component characters.

The genetical and environmental control of yield and its components in spring barley, tillers per plant, grain number and grain weight has been investigated by triple test cross and linear modelfitting analyses.Additive and dominance effects were observed for both grain number and grain weight, but tiller number was almost totally controlled by environmental factors. Epistatic effects were usually absent, only grain number exhibited such effects. The heritabilities of the yield components varied from low (0.15) for tiller number to high (0.51) for grain weight. Yield itself, measured on a single plant basis was mainly under additive and dominance control, with little evidence for epistasis. The heritability for single plant yield was low (0.22).The possibilities for early generation selection for yield are discussed, and the relative contributions of each genetic and environmental component are described.