INTER-GENOTYPIC VARIABILITY AND GENETIC DIVERSITY ANALYSiS IN F4 LINES OF BRASSICA RAPA

Abstract

A field experiment was conducted in the experimental field of Genetics and Plant Breeding Depai-tment, Sher-e Bangla Agricultural University, Dhaka, Bangladesh, to study on inter-genotypic variability and genetic diversity in 10 1 4 lines obtained through intervarieta] crosscs along with 8 released varieties of Brassica rapa during November 2007 to March 2008. Significant variation was observed among all the genotypes for all the characters studied. Considering genetic parameters high genotypic co-efficient of variation (CCV) was observed for number of secondary branches/plant, siliquae/plant. yield/plant whereas days to maturity showed very low CCV. 1-ugh heritability with low genetic advance in percent of mean was observed for days to maturity which indicated that non-additive gene effects were involved for the expression of this character and selection for such trait might not be rewarding. High heritability with moderate genetic advance in percent olmean was observed for plant height and days to 50% flowering indicating that this trait was under additive gene control and selection for genetic improvement for this trait would be effective. Different Multivariate analysis was performed to classiI' 18 genotypes. All the genotypes were grouped into four clusters. Principal Component Analysis, Principal Coordinate Analysis, Cluster Analysis, Canonical Variate Analysis gave similar results. Cluster IV was the largest cluster comprising of 7 genotypes and cluster II was the smallest cluster with 2 genotypes. Cluster II had the highest intra-cluster distance and Cluster I had the lowest intra cluster distance. Inter cluster distance was maximum (11.697) between clusters II and Ill. The results revealed that genotypes chosen for hybridization from clusters with highest distances would give high heterotic F and broad spectrum of variability in segregating generations. The charactersnumber of primary branches/plant, number of secondary branches/plant and days to 50% flowering contributed maximum towards divergence. Considering cluster distance, inter genotypic distance and other agronomic performance (i2 and C 14 from cluster I; C 18 from cluster 11; Cl, G9 and C 12 from cluster Ill and GIG and (117 from cluster IV may be considered to be better parents for future uses in hybridization program.