Morphological traits conditioning sorghum resistance to the African stem borer, Busseola fusca

Sorghum (Sorghum bicolor, L. Moench) is a key cereal to over 500 million people in semi-arid tropics. The crop’s production in subsistence farming ranges between 0.5– 0.8 t/ha compared to potential yields of 10 t/ha.  Busseola fusca, (Lepidopteran Noctuidae) is an economically important pest of sorghum and is associated with 15% yield loss through leaf feeding, deadheart and stem damages. The objective of this study was to identify morphological traits associated with resistance to B. fusca.  Test material was sown in an α-lattice design, consisting of nine plots in three blocks, replicated twice. The rows were 2 m x  0.75 m apart, and the spacing between plants within rows was 0.25 m. At 30 days after sowing, five plants in each row were artificially infested with five larvae/plant. Data was collected on deadheart, leaf feeding, stem damage, trichome density , leaf glossiness and seedling vigour. Data on percentages was arcsin transformed while that of counts was log transformed before ANOVA using Genstat. Treatment means were compared using  protected Fishers’ least significant difference test at P = 0.05.  The ANOVA indicated highly significant (P = < 0.01) differences in all the traits measured. Genotypes that showed reduced damage included ICSA 464, ICSA 472 and ICSA 473.  Most of the resistant genotypes in this study possessed more trichomes, were highly glossy and were more vigorous than the susceptible genotypes. Seedling vigour, glossiness and trichome density could be used as morphological markers to select for sorghum resistant to B. fusca.