Screening of inbred lines of tropical maize for resistance to fall armyworm, and for yield and yield-related traits.
The fall armyworm (FAW) (Spodoptera frugiperda J.E. Smith) is a major cause of crop loss and food insecurity in sub-Saharan Africa. There is a need to identify maize genetic resources with FAW resistance for breeding. The objectives of this study were to screen two sets of diverse maize germplasm and to select genotypes with FAW resistance and desirable yield-related traits. Set I and Set II, containing 60 and 253 maize genotypes, respectively, were selected based on their agronomic potential and adaptability for screening in FAW infested areas in Zambia. Highly significant differences (P < 0.001) were detected among the test genotypes for FAW-leaf damage (FLD) and FAW cob damage (FCD) and agronomic traits. The lowest FLD and FCD were 8.87% and 5.36%, recorded in genotypes CML304-B and CML442, respectively. Five principal components (PCs) accounted for ≥80% of the total variation showing that key traits included reduced anthesis-silking interval (ASI), plant height, FLD and FCD, desirable ear aspect and grain yield. Some genotypes, such as Pool 16 and ZM7114 from Set I, and CZL1310c, CML444-B, CZL15220 and TL1512847 from Set II had low mean FCD and FLD, showing that they were potential sources of FAW resistance. Grain yield was negatively correlated with mean FLD (r = -0.18, p < 0.05), and FCD (r = -0.15, p < 0.05). Promising maize genotypes including CZL1310c, CML444-B, CZL15220, TL1512847 and CML491 were selected for their low mean FLD, FCD, earliness to flowering and high grain yield potential. These genotypes will be useful in developing tropical and sub-tropical maize breeding populations with partial FAW resistance and yield gains.