Abstract

Fall armyworm (FAW) is currently the most destructive insect pest of maize in sub-Saharan Africa (SSA). Varieties that combine high grain yield (GY) with tolerance to FAW would enhance and stabilize maize productivity in SSA. Genotypes resistant to lepidopteran pests like stem borer (SB) could serve as potential sources of alleles for development of FAW resistant varieties. This study was conducted to assess some SB-resistant maize genotypes for FAW tolerance, and to identify genotypes that combined high GY with tolerance to FAW. Twenty-nine white maize genotypes with varying levels of SB resistance were evaluated under artificial FAW-infested and FAW-protected conditions using randomized complete block design with three replicates. Genotypic differences were significant for all the traits under both FAW-infested and FAW-protected conditions. Under FAW-infested condition, GY ranged from 3.44 (FAWTH-8) to 5.81 t ha-1 (FAWTH-1) (mean = 4.61 t ha-1), and from 3.42 (FAWTH-25) to 6.85 t ha-1 (FAWTH-18) (mean = 4 .86 t ha-1) under FAW-protected condition. Across genotypes, FAW infestation reduced GY by 5.1% suggesting that SB resistance could confer tolerance to FAW.  Association of GY under FAW-infested condition with FAW Leaf Damage (FAWLD; r=-0.45) and FAW Ear Damage (FAWED; r=-0.65) were significant. Base index (BI) was significantly correlated with GY (r=0.93), ear aspect (r=-0.84), FAWLD (r=-0.66) and FAWED (r=-0.78). Six moderately resistant genotypes (FAWTH-1, FAWTH-13, FAWTH-4, FAWTH-10, FAWTH-23 and FAWTH-6) with GY ≥ 5.13 t ha-1 and positive BI ≥ 4.0 were identified. The genotypes varied for FAW tolerance. Base index and low FAW damage scores could serve as selection criteria for combined tolerance to FAW and high GY. The identified genotypes are recommended for further development as FAW tolerant varieties.

Key words: Base index, fall armyworm ear damage, fall armyworm leaf damage, maize grain yield, stem borer resistance.