Profiling of Maize Genotypes for Resistance Against Spodoptera frugiperda under Artificial Infestation Conditions

Resistance against FAW infestation

Abstract

The maize crop is increasingly affected by various biotic and abiotic stressors at different growth stages. Among the biotic stressors, the Fall armyworm (FAW), caused by Spodoptera frugiperda (J. E. Smith), has emerged as a significant threat to maize cultivation since its first report in Karnataka, India, in May 2018. Despite the development of numerous strategies and management approaches for controlling FAW infestations, Host Plant Resistance (HPR) to insects remains an effective, economical, and environmentally friendly method of pest control. In this study, we screened 35 maize inbreds to fall armyworm under artificial infestation. The experiment was conducted using an alpha lattice design with three replications during Kharif 2023-24 at the maize experimental area of PAU, Ludhiana. Ten neonate larvae per plant were used to infest each genotype at 14 days after germination. Leaf injury ratings were recorded at 7, 14, 21, 28, and 35 days post-infestation, while ear damage ratings were taken at harvest. Both ratings were measured using the Davis and Williams (1992) scale (1-9). Damage assessment showed that FAW injury peaked at 21 days after infestation (DAI), corresponding to the V6 growth stage, which was identified as the most effective time for screening. Among inbred lines, CML 46 recorded the least foliar damage, while LM 12 and LM 14 were the most affected. Hybrids developed from tolerant inbreds, particularly JH 23128 (CML 46 × CML 72), showed strong resistance, whereas hybrid JH 23135 (VL 181545 susceptible × CML 71 tolerant) suffered the highest damage. This observation necessitated both tolerant parental lines to confer resistance in single cross hybrids for commercialization. Positive correlations between foliar and ear damage (r = 0.84 in inbreds; r = 0.75 in hybrids) indicated consistent resistance across plant parts. Agronomic traits such as plant height, cob characteristics, and grain yield varied significantly among hybrids. JH 23136 produced the highest yield (7.3 t/ha), followed by JH 23132 (7.0 t/ha). Genotypes like CML 46, CML 71, and CML 72 offer strong potential for developing FAW-resistant maize suitable for sustainable cultivation.