Inheritance and Heritability of Heat Tolerance in Several Sorghum Cultivars During the Reproductive Phase

Four sorghum parental lines, RTx430, BTx3197, RTx7000, and B35 and their F₁ and reciprocals, and F₂ progenies were evaluated during their reproductive phases to access the genetic basis of heat tolerance. Heat tolerance was measured under field and greenhouse conditions at College Station, Texas during 1990. Parental cultivars were significantly more heat tolerant than their hybrids. Inheritance of heat tolerance appeared to be associated with two genes with dominant and recessive epistatic effect influenced by maternal effects. Broad sense heritability values were low to moderate due to large environmental effects which may complicate direct selection. B35 was shown to be useful for improvement of heat tolerance.