PhD

The present investigation entitled "Genetic Analysis in Ivygourd (Coccinia
grandis (L) Voigt.) was conducted at the Department of Plant Breeding and
Genetics, College of Agriculture, Vellayani during 1999-2001. Objective of the
study was to estimate the genetic basis of different characters, genetic divergence
in the germplasm and to formulate a selection index for identifying superior types.
The material for the experiment was 90 different local cultivars collected from
different agroclimatic regions. The data for the investigation were collected from
two field experiments, each laid out in Randornised Block Design with three
replications.
In Experiment I a collection of 50 genotypes of ivygourd was grouped into
11 clusters using Mahalanobis D2 statistic and based on eight morphological
characters. Five genotypes Kuriyabandar local I, Kuriyabandar local Ill, Pilangatta
local 11 & III and Kudlu local I, could not be grouped with others and so are kept as
independent clusters. The cluster C IX was found to have maximum intercluster
distance with seven of the eleven clusters formed. This was followed by C 11
which showed maximum divergence with four out of the eleven clusters. The
results suggest that selection of parents from these divergent clusters will be
effective in future hybridisation programme. The three superior crosses identified
were Balthangadi local I x Pilangatta local 11, Bandargrarn local I x Pilangatta local
11 and Seetharnbeta local I x Pilangatta local II. Number of flowers per plant and
number of leaves per plant were found to be the two characters that contributed

maximum for the divergence of the genotypes. So both at phenotypic and cluster
levels, these two characters can be considered as potential contributors of
differentiation in Jvygourd.
In Experiment II the data collected from 40 genotypes of ivygourd were
subjected to analysis of variance and the genetic parameters like variability,
heritability; genetic advance, correlation coefficients and path coefficients were
estimated. Based on the above observation, a selection index was also formulated.
Significant genotypic differences were observed among the 40 genotypes for all of
the sixteen characters studied. High genetic variability was expressed by the
characters fruit yield per plant, number of fruits per plant and number of flowers
per plant. High heritability along with a good genetic advance was found for all
the characters studied, except for number of days for first flower opening which
exhibited high heritability and low genetic advance. These results indicate that the
selection of plants which are phenotypically superior with respect to fifteen of the
characters studied will certainly result in a significant improvement in the next
generation.
The genotypic correlation coefficients were higher than the corresponding
phenotypic and environmental correlation coefficients revealing the fact that
phenotypic expression of these correlations are reduced due to the influence of the
environment. Yield per plant exhibited positive association with all the characters
except number of days for flowering, which had significant negative correlation
with yield. Number of fruits per plant and single fruit weight were the characters
with high direct and indirect effects. Based on the above results, a selection index

was formulated and local cultivars of Alappuzha, Kanjangad, Thirunelli,
Mancheswararn and Nangikadapurarn were identified as the five top ranking
genetically superior ivygourd genotypes.
To sum up, the results of the present study indicates that being strictly a
cross pollinated crop with possibility for vegetative propagation, methods of
breeding which can. be successfully followed are individual plant selection, mass
selection to improve varieties, pedigree method and heterosis breeding and
vegetative propagation of the heterotic combinations. Considerable variability of
the crop has been observed in Kamataka, Andhra Pradesh, Tarnil Nadu and
northern parts of Kerala. There is considerable scope for survey, collection and
maintenance of germplasm. The study highlights the feasibility of producing
commercially viable indigenous selections and hybrids which are early, producing
more number of bold and tender fruits with good storability and resistance to pest
and diseases.