Heterosis among CIMMYT Populations and Chinese Key Inbred Lines in Maize

The objectives of this study were to analysis the combining ability and heterosis between CIMMYT populations and Chinese elite inbreds. Ten populations from CIMMYT were crossed with five Chinese elite inbreds through a 5×10 NCⅡ mating system. Fifty crosses and five commercial hybrids were evaluated in 1998 and 1999 at Wuhan. The results showed that Population Stay Green, Population 43 C11 and Population 21 C2 were the best general combiners for yield traits with Chinese elite inbreds, which may be used as important exotic resources for enhancing the maize germplasm in China. The values of relative heterosis for 13 combinations were over the zero among 50 combinations of CIMMYT populations and Chinese elite inbreds. The Tuxpeno based populations always expressed highly positive combining ability and had high relative heterosis with some Chinese elite inbreds, indicating that they might constitute a potential heterotic pattern in Chinese maize breeding. A8833 and A9245 showed highly negative effects for most of evaluated traits. Population 32, Pool 19 C19, Yellow Syntheses C3 and P500 gave an medium GCA performance for the traits tested and medium relative heterosis level for grain yield, but they can be used as special germplasm. The results of the study provided useful information for utilizing those CIMMYT populations in Chinese maize breeding.