Response of tropical maize inbred lines to maize streak virus and major agronomic traits

Introduction Maize streak virus (MSV) is a major constraint on maize production in the dry and hot tropics, where susceptible cultivars suffer complete yield loss. The objective of this study was to assess the response of tropical-environment-adapted maize inbred lines for MSV resistance and major agronomic traits to identify parental lines for resistance breeding. Methods Seventy-four inbred lines, including six controls, were evaluated under artificial MSV inoculation over two seasons using an 8 × 10 alpha lattice design. Results A significant variability (P ≤ 0.05) was detected among genotypes for MSV resistance and yield components. Area under the disease progress curve (AUDPC) ranged from 0.00 to 240.6, disease incidence from 0 to 100%, and grain yield from 0.54 to 4.99 t ha⁻¹. Genotype-by-season interactions were significant for disease incidence and yield-related traits, with most traits showing moderate to high heritability. MSV disease parameters were negatively correlated with grain yield and agronomic traits. Elite parental lines MM05, MM17, MM19, and MM25 were identified as valuable donor parents combining MSV resistance with superior grain yield and favourable agronomic performance. Lines MM10, MM11 and MM72 were identified for hybrid breeding due to their combination of high grain yield and MSV tolerance. Finally, MM36 and MM35 were recognised for their outstanding grain yield performance, attributable to their MSV tolerance. Discussion The identified inbred lines provide complementary sources of MSV resistance and represent valuable donor parents for introgression and developing high-yielding MSV-resistant maize hybrids.