Line × Tester Analysis for Estimation Combining ability of some New Yellow Maize Inbred Lines for Grain Yield and Downy Mildew Resistance

Abstract

A line×tester analysis was performed at Sakha Research Station; during summer 2017, using twenty new yellow maize inbred lines and two testers; inbred line Sk-4 and single cross SC180. The resulting 40 F1 crosses in addition to four check hybrids were evaluated in two trails during summer 2018. The first trail; for yield and other traits, was performed at Sakha and Sids Agricultural Research Stations. The second trial; for downy mildew disease resistance, was carried out under two levels of nitrogen fertilization in the disease nursery at Sakha Station. Significantly differences were detected between the two locations for the most studied traits and between the two nitrogen levels for downy mildew resistance. Significant of differences were observed among lines, testers and their interaction for all studied traits, except among testers for downy mildew resistance and line×tester interaction for plant height, ear height and downy mildew resistance. The non-additive gene effects were predominant in the inheritance of grain yield, ear length, ear diameter and downy mildew resistance. For general combining ability effects, the best general combiners were Sk5013/71 for grain yield and downy mildew resistance. While, the best tester was Sk-4 for grain yield and most traits. The desirable hybrids for specific combining ability effects were Sk5002/62×Sk-4, Sk5005/66×Sk-4 and Sk5021/74×SC180 for grain yield and Sk5004/65×SC180 for downy mildew resistance. Single cross Sk5013/71×Sk4, also three-way crosses Sk5010/69×SC180 and Sk5013/71×SC180 were superior for grain yield and high resistance to downy mildew resistance. These crosses could be use in maize breeding program.