Genetic Studies of Grain Yield and Resistance of Single Cross Maize Hybrids to Turcicum Leaf Blight

Abstract

Maize (Zea mays L.) is a vital cereal crop globally, yet its productivity is frequently constrained by foliar diseases such as Turcicum Leaf Blight (TLB), caused by Exserohilum turcicum. The present study is aimed to evaluate the genetic variability, combining ability, heterosis, and TLB resistance among 50 single cross maize hybrids developed through a line × tester mating design involving five lines and ten testers. The genotypes were evaluated for agronomic traits and TLB resistance under field conditions. Analysis of variance revealed significant genetic variability for all traits, with grain yield exhibiting the highest heritability (99.09%) and genetic advance (64.18%). General combining ability (GCA) and specific combining ability (SCA) analyses showed that both additive and non-additive gene actions contributed to trait expression. Hybrids such as JLML-97555 × JLSN-81 and JLML-01666 × JLSN-34 demonstrated high yield potential and favourable combining ability. Heterosis for grain yield was pronounced, with better-parent heterosis reaching up to 98%. Screening for TLB resistance showed that although all hybrids were resistant at tasselling, only 38% retained resistance at physiological maturity. Parental lines JLML-01888 and JLML-94333 and testers JLSN-34 and JLSN-73 conferred durable resistance. The findings emphasized the potential of combining ability analysis and hence, hybrids that integrate high yield and durable disease resistance were identified which serve as valuable material for maize improvement programs.