Characterization of maize genotypes for genetic diversity on the basis of inter simple sequence repeats.

Genetic diversity in crops is essential to make improvements related to superior germplasms. Implementation of molecular markers to identify suitable genotypes speeds up the breeding progress by enhancing selection efficiency. This study was carried out to probe genetic diversity among 21 maize genotypes using 20 inter simple sequence repeat (ISSR) markers. We identified a total of 190 polymorphic bands with an average of 9.5 alleles per primer. The highest number of polymorphic bands (17) was found using ISSR marker UBC-10, whereas the lowest number of polymorphic bands (4) was found using UBC-809. The coefficient of genetic similarity ranged from 0.888 to 0.118%. The highest similarity was found between accessions 12 (015224) and 9 (015114), whereas the lowest similarity was found between genotypes 20 (EV-5098) and 14 (015030). The polymorphism information content ranged from 0.17 to 0.47. A dendrogram was generated based on Jaccard's distance matrix. The genotypes were found to group into two major clusters that could be further partitioned into two sub-clusters. Genotypes located within the same cluster are genetically more closely related to each other. The present study efficiently identified diverse genotypes that may be used for creating new varieties with distinct characteristics. The identified genotypes could be used as parents for future development of diverse populations.

Analysis of genetic traits for drought tolerance in maize.

Fifty-four genotypes of maize were crossed and evaluated in the field during the crop season in February 2012 under both normal and water stress conditions. To identify the major parameters responsible for variation among genotypes, single linkage cluster analysis and principle component analysis (PCA) were carried out. Thirteen characters were studied. The PCA showed that the first six components, with eigen values >1, contributed 82.30% of the variability among the genotypes under normal field irrigation conditions while other PCs (7-13) had eigen values less than 1. Under drought conditions, the first four PCs, with eigen values >1, contributed 64.79% of the variability among genotypes while the other PCs (5-13) had eigen values less than 1. In the absence of water stress, heritability ranged from 68% (sucrose content) to 99% (plant height) and genetic advance ranged between 158.43% for stomatal frequency and 0.87 for biological yield. Under drought conditions, the coefficient of variability (CV) was 1.43-7.79, whereas estimates of heritability ranged between 68% and 99% for sucrose content and leaf area, respectively. The values of genetic advance ranged between 153.41 for stomatal frequency and 0.47 for nitrogen content. CV was 1.52-7.38 under drought conditions. The results indicated that the plant characters studied were under the control of additive genetic effects and suggested that selection should lead to fast genetic improvements. Clusters with superior agronomic types were identified and could be exploited for the transfer of desirable genes to improve the yield potential of the maize crop.

Relationship between genetic parameters in maize (Zea mays) with seedling growth parameters under 40-100% soil moisture conditions.

We estimated the association of genetic parameters with production characters in 64 maize (Zea mays) genotypes in a green house in soil with 40-100% moisture levels (percent of soil moisture capacity). To identify the major parameters that account for variation among the genotypes, we used single linkage cluster analysis and principle component analysis. Ten plant characters were measured. The first two, four, three, and again three components, with eigen values > 1 contributed 75.05, 80.11, 68.67, and 75.87% of the variability among the genotypes under the different moisture levels, i.e., 40, 60, 80, and 100%, respectively. Other principal components (3-10, 5-10, and 4-10) had eigen values less than 1. The highest estimates of heritability were found for root fresh weight, root volume (0.99), and shoot fresh weight (0.995) in 40% soil moisture. Values of genetic advance ranged from 23.4024 for SR at 40% soil moisture to 0.2538 for shoot dry weight in 60% soil moisture. The high magnitude of broad sense heritability provides evidence that these plant characters are under the control of additive genetic effects. This indicates that selection should lead to fast genetic improvement of the material. The superior agronomic types that we identified may be exploited for genetic potential to improve yield potential of the maize crop.