Heterotic grouping of QPM inbred lines and quality profiling based on genetic and molecular markers

Abstract

The present investigation entitled Heterotic grouping of QPM inbred lines and quality profiling based on genetic and molecular markers was undertaken to study combining ability effects for yield and quality traits, understand the heterotic pattern and estimate the genetic relationship and diversity among QPM inbreds using molecular markers in quality protein maize. Ten QPM inbred lines were hybridized following Griffing s Method 2, Model 1 in a half diallel fashion. Experimental materials comprising of ten inbred lines, forty five single cross experimental hybrids, three hybrids along with two standard checks were evaluated in and#945;-RBD with two replications during kharif 2016 (E1) and 2017 (E2) at Palampur (L1) and Akrot (L2). The analysis of variances indicated significant differences among genotypes for grain yield per plant and other component traits in all the environments. Also, significant differences for environment (E) and lines × environment interaction for most of the traits except cob girth indicated a definite role of environment on the performance of genotypes/crosses. Variances due to GCA, SCA and their interaction with environment were significant for most of the traits under Palampur and Akrot conditions, indicating the importance of testing parents as well as hybrids across environments. On the basis of per se performance, heterosis and combining ability for grain yield per plant and other component traits, the cross combination P1 × P7 at both the locations was found best, whereas P3 × P8 and P1 × P4 under Palampur conditions were found best. Parent P1 and P5 were the most promising general combiners for grain yield per plant and most of the yield component traits at both locations. For most of the traits, there was preponderance of non-additive gene action which reaffirms the importance of heterosis in maize. At molecular level, 28 SSR primers amplified 97 polymorphic alleles with an average of 3.46 alleles per primer. Size of amplified alleles ranged from 50 to 480 bp. Mean polymorphic information content was 0.28 showing low level of SSR polymorphism as the present investigation involved few closely related cultivars. Cluster analysis based on SSR data differentiated 48 maize genotypes into two major clusters. Assigning inbreds into different heterotic groups is fundamental for exploitation of heterosis for hybrid development. Heterotic grouping based on morphological trait and molecular markers grouped ten QPM inbred lines in to four heterotic groups. Results indicated that SSR markers effectively and efficiently assigned the inbred lines to heterotic groups for grain yield. This will help to establish maize inbred lines for the purpose of reducing the number of single crosses and their evaluation using the lines from the different heterotic groups. Overall, cross combination P1 × P7 with high heterosis and per se performance for yield was better than that of best check for grain yield per plant, and was found moderately resistant to banded leaf and sheath blight (BLSB), turcicum leaf blight (TLB) and maydis leaf blight (MLB) over the environments and can be further exploited. newline