Phenotypic and molecular divergence in maize (Zea mays L.) ecotypes

Genetic characterization of maize genotypes is of great importance in maize breeding program to identify diverse populations and divergent genotypes. Divergence and genetic diversity were assessed in a set of 20 maize genotypes representing popcorn, white corn, sweet corn and yellow corn, through morphological characteristics and Random Amplified Polymorphic DNA (RAPD) markers. Field experiment was conducted in randomized complete block design with three replications. Morphological data revealed that sweet corn genotype SCLY-1 was earlier in days to 50% pollen shedding than other genotypes while white corn genotype WL-3 was earlier in days to 50% silking. Maximum plant height was recorded for PCLY-5 (133.3 cm) while lowest for WL-4 (92.8 cm), whereas highest ears height was recorded for popcorn PCLY-1 (64.4 cm) and lowest (29.4 cm) for SCLY-5. The yellow corn had maximum (4.5 kg) grain yield at harvest as compared to sweet and popcorn (3.0 kg). Negative but weak correlation was recorded between ear height and grain yield. Cluster analysis based on yield related parameters grouped all the studied genotypes in to five sub clusters. Molecular genotyping based on four primers amplified 37 loci which were (100%) polymorphic. Maximum elven loci were identified by primer GLA-04, while minimum was reported for primer GLA-03. The loci GLD-18B1000, GLA-04B300 recorded highest gene diversity (0.500) followed by loci GLE-05B750, GLE-05B650 and GLE-05B550. The loci of primer GLD-18 (GLD-18B1000) detected highest alleles evenness and Simpson's diversity index of 1.00 and 0.526, respectively. Maximum gene diversity (0.354) among populations were recorded for yellow corn, while the minimum was detected for white corn (0.254), while genotypic diversity was same for all maize types. Cluster analysis based on molecular genotypic data grouped the maize genotypes into four distinct groups. Lack of concordance was observed while comparing the clustering based on phenotypic and molecular data. The overall diversity among the studied maize genotypes could be used in future maize breeding program.