Heterosis for Grain Yield and Leaf Area and Their Components in Two‐ ✕ Six‐Rowed Barley Crosses1

Twelve hybrids between two‐ and six‐rowed barley varieties were evaluated for heterosis for two complex traits through the component interaction approach. On the average, very low levels of heterosis were found for the complex traits (grain yield per plant and total leaf blade area per plant). Data were presented on some of the possible causes of the failure of component niteraction to produce heteroic effects for the complex trait. The negative association of kernels per head and weight per kernel and the lack of additivity for kernels per head were determined as possible reasons for the failure of component interactions to occur and produce heterosis for grain yield. No apparent reasons were found for the failure of component interaction to occur for TLA. Reciprocal differences in the components among the parental varieties may not have been sufficiently large enough to promote component interactions for TLA.