Combining Ability Analysis of Maize Inbred Lines in Ethiopia

Abstract

The study was initiated to estimate combining ability of maize inbred lines and crosses using line by tester analysis. Fifty entries consists 48 F1 single crosses developed from 24 inbred lines and 2 testers using line x tester design and two commercial check hybrids used in the study. The experiment was conducted using alpha lattice design with two replications. Analysis of variance revealed existence of significant genetic variation among genotypes for all studied traits except for plant aspect (PA). Location x entry interaction for most of the traits was not significant which suggests hybrid performance was consistent across tested locations. Line x tester analysis of variance showed that mean squares due to GCA of lines were significant (p< 0.01 or p< 0.05) for all studied traits. Mean squares of tester GCA and SCA were significant for most of studied traits. This indicates that both additive and non-additive gene effects had contributed for the variation of the crosses. However, higher proportional contribution of additive gene action for all studied traits was obtained. Several lines and crosses were identified as good general and specific combiners for yield and yield related traits. Lines L23, L11, L15 and crosses L2xT1, L3xT1, L8xT1, L11xT1, L23xT1 and L13xT2 were found to be good general and specific combiners, respectively. In conclusion, the stated inbred lines with desirable gca effects and cross combinations with desirable sca effects for grain yield and yield related traits could be used as useful genetic material.

Performance of early-maturing topcross maize hybrids across multi-environments

“…The interaction effect of the environment with genotype, line, tester and line × tester was significant for GYLD and most agronomic traits, signifying that the genotypes were greatly influenced by the environments for most of the traits measured. Previous studies (Beyene et al, 2011;Murtadha et al, 2018;Abenezer et al, 2020) reported significant genotype × environment (G × E) interaction effect for yield and secondary traits in maize and noted the presence of wide variability among tested genotypes and environments. Genotype by Environment Interaction (GEI) effect is an important factor in breeding programs and sometimes confounds the genetic potential of a candidate variety.…”

“…Three lines (TZEEIOR-197, TZEI-129 and TZEI-8) had significant negative GCA effects for flowering traits (Table 4), suggesting that they could be used for developing early maturing genotypes. The importance of significant negative GCA effect for days to 50% anthesis and silking has previously been suggested for the development of early maturing maize varieties (Sundararajan and Kumar, 2011;Abenezer et al, 2020).…”

“…Line TZEI-13 combined a significant negative GCA effect for PHT with significant negative GCA effect for root and stem lodging, whereas four lines (TZEEIOR-197, TZEI-129, TZEI-17 and TZEI-8) had significant positive GCA effects for stem lodge, which is undesirable. Girma et al (2015) and Abenezer et al (2020) in their study suggested that inbred lines with negative GCA effects for plant height often produce hybrids of smaller stature. Two maize inbred lines (TZEI-129 and TZEI-17) had significant negative (desirable) effects for husk cover score, while two other maize inbred lines (TZEI-13 and TZEI-8) had significant positive GCA effects for the trait.…”

“…The SCA estimates of the topcrosses show irregular patterns, thus indicating the complexity in predicting a cross' SCA effect from GCA estimates of its parents. Abenezer et al (2020), Dey et al (2014); Talukder et al (2016) and Zhang et al (2015) suggested that hybrids with high SCA effects from parents with low GCA effects might be due to non-additive gene action, that is, dominance gene effect and epistasis. Results from the study revealed that in three of four instances, crosses between parents with high GCA effect for grain yield resulted in hybrids with low SCA effect for grain yield which could be attributed to lack of complementarity of additive gene action in some of the crosses.…”