GENETIC VARIABILITY AND MOLECULAR CHARACTERIZATION IN ONION (Allium cepa L.)
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Date
2018-07
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University of Horticultural Sciences, Bagalkot
Abstract
A field experiment was conducted during late Kharif 2017-18 to study the
genetic variability, correlation, path coefficient analysis, genetic diversity and
molecular characterization for growth, bulb and quality related characters in onion
with 40 genotypes in randomized block design with two replications. The quantum of
genetic variation as indicated by the higher values of genotypic co-efficient of
variation (GCV) was highest in number of centers per bulb and bulb weight followed
by neck thickness of bulb. However, the character plant height at 30 DAT with least
GCV as compared to the other characters. High heritability coupled with moderate
genetic advance as percentage of mean were reported for the bulb yield per plot,
total yield, T.S.S. of bulb, marketable yield, plant height at 60 DAT and polar bulb
diameter. The high heritability coupled with high genetic advance as percentage of
mean for traits like bulb weight, neck thickness of bulb and number of centers
per bulb.
The character association studies revealed that bulb weight showed positive
and significant correlation with growth as well as bulb related trait. Results of path
coefficient analysis of various characters contributing towards bulb weight showed
that number of leaves per plant at 30 DAT had highest positive direct effect followed
by plant height at 90 DAT, days to maturity, polar bulb diameter, leaf area index,
neck thickness of bulb, equatorial bulb diameter and plant height at 30 DAT.
Mahalanobis D2 analysis indicated considerable diversity and 40 genotypes were
grouped into seven clusters. The cluster VII showed maximum intra cluster diversity.
Inter cluster distance revealed the maximum divergence between clusters II and IV.
Neck thickness of bulb contributed maximum to overall genetic diversity. From the
study it can be concluded that the genotypes ON-24, ON-8, Bhima Super and ON-22
recorded higher yield and found superior over all other genotypes. Based on SSR
marker assay, 40 onion genotypes were analyzed. The PIC values ranged from 0.07 to
0.77 with an average of 0.38. It may be concluded that the primer ACM134 and
ACM138 can be used for genetic diversity analysis in onion.