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

Abstract

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.

Heterosis and Hybrid Seed Production in Barley

“…They concluded that yield heterosis is not only expressed at low seeding rates, but that it can result from contributions from different yield components in different environments. Carleton and Foote (1968) did not find heterosisi for yield or for leaf area in tworow by six-row crosses, even though the parents differed reciprocally for components of yield and for components of leaf area. Upadhyaya and Rasmusson (1967) also found some hybrids that exhibited no heterosis for yield, even though the parents differed reciprocally for the components of yield.…”

Heterosis and mixing effects in barley under drought stress

“…The increasing effect of heterozygosity with increasing levels of stress confirms the observations of Finlay (1964) for grain yield of barley. Carleton and Foote (1968) observed no heterosis in crosses between two-rowed and six-rowed barley. They argued that the growing conditions in their glasshouse experiment might have been too close to optimum to exhibit heterosis.…”

Barley improvement

“…Heterosis varies in degree, and may be shown by various plant attributes, such as size, tillering capacity or grain size [24,25]. The value of this approach is not universally accepted, since 'hybrid vigour' should be 'fixable' in homozygous plants.…”