Published online by Cambridge University Press: 19 September 2011
Genetic analysis of sorghum resistance to stem-borers was performed in a 6 × 6 diallel cross. The results indicated that resistance to stem-borers is polygenically inherited. F1 hybrids did not differ significantly from mid-parental values suggesting intermediate inheritance. However, resistance was partially dominant to susceptibility. Combining ability analysis showed that resistance to primary damage, i.e. % ‘dead heart’ was governed by both additive and non-additive type of gene actions while secondary damage, i.e. % stem tunnelling was governed predominantly by additive gene action. It was noted that the inheritance patterns of primary and secondary damage were different. Tunnel length showed positive correlation with the number of larvae per plant and negative association with plant height, but had no correlation with grain yield per plant. On the basis of larvae recovered from the tunnelled plants, Chilo partellus was found to be the predominant stem-borer species followed by Sesamia calamistis, Eldana saccharina and Busseola fusca. Significance of genetic studies of host plant resistance in deciding breeding strategies for insect resistance has been discussed.