EFEITOS GÊNICOS, HETEROSE E DEPRESSÃO ENDOGÂMICA EM CARACTERES DE SORGO FORRAGEIROTwo crosses involving three sorghum lines (S. bicolor L. Moench) BR 007A x BR 501R and BR 008A x BR 501R resulted in two forage hybrids: BR 601 and BR 602. The hybrids and their generations F2 and F3, in total of nine genotypes, were evaluated in two planting dates (normal and second season) as to several yield and forage quality characters: genetic effects, mid-parent heterosis, heterobeltiosis and inbreeding depression in F2 and F3 generations were evaluated. The following conclusions were obtained: (a) compared to the normal planting, the grain sorghum hybrids showed in second season, smaller plant height, earlier flowering, smaller green, and dry matter weight and higher protein content, stalk proportion and smaller planicle proportion; (b) heterosis for dry matter was positive and negative for protein at the two planting dates of the two hybrids; (c) inbreeding depression was positive for the F2 generation of the BR 602 hybrid at normal planting date, indicating that the commercial use of F2's seeds is not recommended; (d) the additive genetic effects were predominant for most of the characters, of the hybrid of BR 007A x BR 501R, used as grain dominant effects were important for yield characters determination at the two planting dates in forage hybrid BR 008A x BR 501R; (e) dominance effects explained most of the significant heterosis of several characters.
forage sorghum; genetic effects; heterosis; inbreeding depression
