Resumo

PENA RAMOS, Alfonso et al. Heterosis and combining ability for forage yield and quality in six maize populations. Rev. mex. de cienc. pecuarias [online]. 2012, vol.3, n.3, pp.389-406. ISSN 2448-6698.

Six corn populations drawn from outstanding forage quality germplasm, and 15 of their direct crosses were assessed in four sites located between 1,117 and 1,932 m asl. The purpose of the present study was to determine general and specific combining ability and mid parent heterosis for whole plant dry matter (TDM), ear dry matter (EDM), stover dry matter (SDM), in vitro dry matter digestibility (IVDMD), neutral detergent fiber content (NDF) and crude protein (CP). Populations showed significant differences for all dry matter yield characteristics, but not for forage quality, while crosses showed differences for EDM and IVDMD. General combining ability effects (GCA) were high and significant only for TDM, while specific combining ability effects (SCA) were significant for IVDMD. Population P3 had the highest GCA for TDM (0.66 t ha^-1) and P5F for EDM (0.49 t ha^-1). Early cross P1*P2 had the highest heterosis for TDM (17.6 %) and highly significant SCA effects for both TDM and IVDMD (1.48 t ha^-1 and 22.6 g kg^-1, respectively), while crosses P2*P5F, P1*P4 and P1*P6F had high mid parent heterosis for EDM, with values ranging from 18.6 % to 26.2 %. None of the crosses showed mid parent heterosis for forage traits of importance.

Palavras-chave : Zea mays L.; Heterotic patterns; Forage yield; Forage quality; Diallel crosses.