Combining ability and heterotic pattern in West African sorghum landraces
Heterotic grouping based on combining ability for traits of interest, in addition to plant performance and genetic relationship among germplasm, would be useful in planning crosses in breeding programmes. This study aimed at determining the combining abilities of selected landraces for morphological and physiological traits under contrasted environments and identifying the suitable heterotic grouping method for superior hybrid production. For this purpose, nineteen accessions representing different origins and population structure among West African Sorghum Accessions Panel (WASAP) and two female lines, were used in « Line x tester » mating design to produce thirtyeight (38) hybrids. Analysis of variance showed significant general combining ability and specific combining ability effects for grain weight, plant height, days to flowering, panicle length and chlorophyll content implying existence of heterotic responses for these traits. Both additive and non-additive gene effects were important in controlling the inheritance of the traits. Parents K31.3, K37 and Ni331 were the best combiners for grain weight, providing the opportunity for breeders to improve grain yield under diverse environments. AVG-1 x K31.3 and AVG-1 x Tg148 were the superior hybrids. Combining ability based heterotic grouping methods classified sorghum accessions into four groups. The heterotic group’s specific and general combining ability (HSGCA) method was the suitable in predicting hybrid superiority. This combining abilities based heterotic grouping study is an additional tool that breeders could use to identify the best parents for superior hybrids development in West Africa.
Key Words: Combining ability, heterotic groups, sorghum, West Africa