Combining Ability of Maize Inbredlines for Secondary Traits of Adaptation to Multiple Cropping Systems

Abstract

Selecting genotypes based on secondary has been employed in crop improvements to various managments. However their importance in maize  breeding has been limited. This study was conducted to identify high yielding maize hybrids and to study combining abilities of maize inbredlines  for secondary traits of adaptations to maize-bean intercropping. Maize genotypes (G=42) were planted at two locations in 6x7 α-lattice design as  maize-bean intercrop and as sole maize. All data were collected and analyzed for individual Management (M) and Environments (E) followed by  across M and E using random model in SAS. Significant G, E, M, Line (L) and Tester (T) effects were observed for most of the traits measured while  LxT, ExM, ExG, MxG, ExMxG, MxL, MxT and MxLxT effect for few. Relative reduction (RR) varied from - 11.7% to +5.4%. Stalk diameter (SD), Yield (GY),  Leaf area/area index (LA/LAI) and Ear height (EH) of the G decreased opposed to Plant height (PH) and Leaf number (NL) in maize-bean  intercropping. Heritability (H2) ranged from 0.49(LAI) to 0.98(EH). General combining ability (GCA) effects for L varied from -0.77** to 0.89** for GY,  -54.07** to 95.4** in leaf area (LA); - 23.6** to 25.1** in PH, -1.42** to 2.0** in SD and -0.99** to 1.35** in NL. Four hybrids (Entry: 2, 3, 4 and 18)  performed well under sole maize and showed resilience under maize-bean intercropping conditions were recommended for possible release. Five  lines (L2, L3, L4, L18 and L19) showed desirable GCA effects across managements were identified to start crossing program.