Genetics of Yield and Panicle Components in Grain Sorghum Hybrids

Five generations (P₁,P₂, F₁, F₂, and F₃,) of eight sorghum hybrids were studied for determining the gene effects following five parameter model of Hayman (1958). Heterosis for grain yield was highest in CSH 2 followed by CSH 1, CSH 5 and CSH 6. In general, magnitude of inbreeding depression in F₂ and F₃ generations was associated with the magnitude of heterosis. Heterosis for grain yield could arise from different mechanisms. Preponderanc of dominance (h) was observed for grain yield as well as for panicle components. However, in CSH 2 additive (d'), additive x additive (i) and dominance x dominance (i) components for yield and yield contributory characters were more important whereas in CSH 6, d' and i were effective in increasing the yield. In CSH 5 the components h and l were in the same direction indicating duplicate type of epistasis. The complementary type of epistasis for grain yield was observed in other hybrids.