Abstract
The study included characterization of brinjal accessions using morphological and molecular markers, genetic diversity study and combining ability studies of diallel crosses involving 8 genotypes. The accessions exhibited wide range of variation on different morphological and qualitative characters, yield and yield components. Among 100 accessions of brinjal SM042 was the best in respect of number of fruits per plant and yield. In all the traits, genotypic coefficient of variation (GCV) was always smaller than phenotypic coefficient of variation (PCV). Narrow differences between GCV and PCV and high heritability coupled with high genetic advance confirmed least environmental effects on number of fruits and yield per plant. which offered better scope for selection. Based on multivariate analysis. the accessions were grouped into 8 clusters. There was no relationship between genetic divergence and geographical distribution of the accessions. Yield per plant had the maximum contribution towards total divergence. From the isozyme analyses using peroxidase (PRX), glutamate oxaloacetate transminase (GOT) and malate dehydrogenase (MDH), 9, 2 and 5 zymotypes were observed, respectively. Zymotypes P3 (in case of PRX), G, (in case of GOT) and M3 (in case of MDH) were found most frequent which covered 34, 91 and 36% of the 100 brinjal accessions. Using hierarchical clustering based on isozyme analysis. 100 accessions were grouped into 6 clusters. Genetic diversity of 100 accessions were analyzed using variation at 34 RAPD loci, of which 82.35% were polymorphic. The highest pair wise genetic distance was 0.636 in between SM038 and SM024. The mean gene diversity among all the accessions was 0.22. The UPGMA dendrogram, based on Nei's genetic diversity, demonstrated 8 clusters. Clustering of the accessions based on morphological characters did not match with the clustering obtained from isozyme and RAPD analysis. Studies on interrelationships among yield and yield components revealed that genetic correlation coefficient was higher than corresponding phenotypic ones for all the studied characters, thereby establishing strong inherent relationships among them. Path coefficient analysis showed that the breadth of fruit had maximum direct effect on yield per plant followed by number of fruits per plant at genotypic level. Success of crossing varied from 13.33 to 80% during diallel crosses (without reciprocal) between selected eight accessions. Out of 28 cross combinations. 15 crosses showed significant positive hybrid vigour in respect of fruit yield per plant. The highest better parent heterosis (62.86%) was found in P7 x Pg cross combination with respect to fruit yield/plant. The mean square values for combining ability analysis showed that both general combining ability (GCA) and specific combining ability (SCA) were highly significant for all the characters studied, indicating that additive and non-additive genetic components were responsible for expression of those characters. Parents SM042, SM102, SM108 and SM138 were good general combiners for almost all the important characters. Estimates on specific combining ability (SCA) and heterosis in F, generation showed that there were a good number of crosses having significantly positive and expected negative effects for different important characters of brinjal. indicating the possibilities of exploiting these crosses or use of these crosses in the development of hybrid varieties.