Heterosis and combining ability for ear yield in a diallel cross among six maize varieties

Abstract

The objective of this study was to estimate the general and specific combining ability effects and heterosis value for ear yield from e diallel cross among six varieties of maize (Zea mays L.) under breeding at the Centro Nacional de Pesquisa de Milho e Sorgo (CNPMS) at Sete Lagoas, MG, Brazil. The treatments were: CMS 04, CMS 05, CMS 11, CMS 12, CMS 22, CMS 28 and their 15 possible F₁ hybrids. The combined analysis showed general and specific effects to be highly significant (P < 0.01), as well as their interactions with locations. There is an indication of variability among varieties with the presence of additive and nonadditive gene effects. The varieties CMS 04 and CMS 05 presented the highest values for general combining ability effects, 142.82 and 233.93, and mean ear weights of 4.528 kg/ha and 4.445 kg/ha, respectively. The hybrids CMS 05 x CMS 28 and CMS 11 x CMS 28 presented the highest values for specific combining ability effects of 462.28 and 392.87, respectively. Heterosis percentual values related to parental mean were 21.16% and 17.49% and to the highest yialding parent were 12.92% and 13.28% for the hybrids CMS 05 x CMS 28 and CMS 11 x CMS 28, respectively. Mean yield of parentals (4.127 kg/ha) was lower tham mean yield of the 15 hybrids (4,433 kg/ha). The highest mean yield was 5.026 kg/ha for the hybrid CMS 05 x CMS 28.