Heterotic grouping of maize (Zea mays L.) inbred lines developed from landraces of North East Hill Region (NEHR) of India
Loading...
Date
2022-09
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam
Abstract
Hybrid breeding programs are dependent on successful exploitation of heterosis and the efficiency with which inbred lines can be assigned to opposing heterotic groups. The current study sought to determine the heterotic grouping of locally developed maize inbred lines in order to identify the most efficient grouping method. In all, 160 hybrids obtained by crossing 80 inbred lines with two standard testers (LM-13 and LM-14) in a Line × Tester (L × T) fashion were evaluated along with three checks over two seasons in an alpha lattice incomplete block design. The 80 inbreds were also genotyped with 34 polymorphic SSR markers. Analysis of variance revealed highly significant (P < 0.01) Genotype and Genotype × Environment interaction for all the traits under study. To reduce environmental effects and maximize the correlation between the true and predicted genotypic values, best linear unbiased predictions (BLUP) were calculated. General and specific combining abilities of the parental inbreds/ crosses and genetic distances were determined and followed up by classification of the inbreds into heterotic groups (LM-13 and LM-14) using four different methods- a) Specific combining ability (SCA) effect of grain yield; b) General combining ability (GCA) effects of multiple traits (HGCAMT); c) Heterotic grouping based on general and specific combining ability (HSGCA) for yield; and d) SSR based genetic distance (SSR_GD). A comparison of these grouping methods revealed that the HSGCA and SCA methods were most efficient. There was also a close correspondence among these methods for grouping similar inbreds into the same heterotic group. As determined by the SSR_GD method, the genetic distance between the divergent testers LM 13 and LM 14 was maximum (1.079) for the material under study. A full diallel analysis (Griffing’s Model 1 Method 1) in a subset of inbreds studied revealed significant GCA and SCA mean square values for all ear/kernel traits. Based on the GCA/SCA ratio however, a preponderance of nonadditive gene action mainly over-dominance was detected for all ear/grain traits. Significant reciprocal differences were also detected implying the direction of the crosses are important. The per se parental performance was a poor predictor of hybrid performance for ear/kernel related traits. Association studies of total grain weight with SCA and GCA effects for both L × T and diallel analysis indicated that low GCA combiners also are required to be incorporated in heterotic groups. While all the crosses generated from diallel matings recorded significant mid and better parent heterosis, hybrid combinations P10×P9, P8×P4, P8×P7, P1×P8, P6×P4 and P3×P8 in particular were at par/superior for multiple traits when compared with the standard commercial checks used in the study.
Description
Keywords
Maize, Genetic techniques