ASSESSMENT OF GENETIC DIVERGENCE IN MUSKMELON (Cucumis melo L.) UNDER RAYALASEEMA CONDITIONS OF ANDHRA PRADESH
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Date
2018-08-18
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COLLEGE OF HORTICULTURE ANANTHARAJUPETA-516 105, Y.S.R. DISTRICT, ANDHRA PRADESH
Abstract
The present investigation entitled “Assessment of genetic divergence in
muskmelon (Cucumis melo L.) under Rayalaseema conditions of Andhra Pradesh”
was carried out during kharif, 2017 at College of Horticulture, Anantharajupeta. The
experiment was conducted with an objective to identify divergent genotypes at
morphological and molecular level to be used as donor parents in crop improvement.
Twenty five genotypes along with one check were sown in a randomized block design
with three replications and the data on 35 yield and yield attributing traits were
recorded.
The analysis of variance revealed significant differences among all the
genotypes indicating the presence of sufficient amount of variability for the characters
studied. Wide range of variability was observed for node number of first fruit set,
yield per plant, fruit volume and fruit weight, indicating the scope for selection of
suitable initial breeding material for further breeding programme.
On the basis of mean performance of the genotypes among the traits studied,
the following were identified as promising lines for further crop improvement in
muskmelon viz., A18 (Suvarna) was found to be better in performance for vine length
and number of fruits per plant. The better performance for yield per plant, fruit
volume, fruit weight and fruit diameter was recorded by accession
A14 (Improved Sharbathi), fruit length by A6 (Papasa), TSS, number of nodes, total
sugars and fruit firmness and beta carotene by A13 (Alpur-1).
The study on genetic parameters revealed that the difference between PCV and
GCV was very low for most of the characters which implies that the influence of
environment on the traits was negligible. In muskmelon genotypes, high heritability
in conjunction with high genetic advance as percent of mean was recorded in
characters viz., vine length, number of nodes, node at which first pistillate flower
appeared, ratio of male to female flowers, node number of first fruit set, number of
fruits per plant, yield per plant, fruit volume, fruit length, fruit diameter, cavity length,
cavity diameter, fruit weight, TSS, titrable acidity, flesh thickness, peel thickness,
fruit firmness, total sugars, ascorbic acid and β-carotene, which suggests the
predominant role of the additive genetic component in governing of these traits and
improvement through simple selection possible.
The D2
analysis was carried out for 29 characters which partitioned the twenty
five genotypes in to six clusters. The inter cluster D2 value is the main criterion for
selection of genotypes. The maximum inter cluster distance was found between
cluster VI and V which, are genetically more divergent and selection of parents from
these diverse clusters for hybridization programme would help in achieving novel
recombinants in muskmelon.
In this study, genotypic correlation was higher than phenotypic correlation for
all the traits under study indicating their highly heritable nature. It was observed that
number of fruits per plant and fruit weight showed highly positive and significant
association with fruit yield. Fruit characters viz., fruit volume, fruit length, cavity
length and flesh thickness were found to be positively correlated with fruit weight.
The path coefficient analysis revealed that vine length, days to appearance of
first staminate flower, fruit length, fruit diameter, number of fruits per plant, fruit
weight, fruit firmness and ascorbic acid had direct positive effect on yield. These
findings showed that direct selection on the basis of the above characters will be
rewarding for crop improvement in muskmelon.
Molecular characterization by 20 SSR primers enabled to know the diversity
among 25 muskmelon genotypes studied. Out of 20 SSR primers, 19 SSR primers
amplified and exhibited polymorphism. High PIC, He and Ho registered with the
SSR’s prompts the deeper insight of molecular complexity involved in the gene pool.
Thus, simultaneous analysis of genotypes at morphological and molecular level would
assist in selecting the genotypes with desirable traits for muskmelon improvement
programme without any ambiguity of environmental interactions.
Description
1. To assess the nature and magnitude of genetic variability present in the
muskmelon germplasm.
2. To study the degree of genetic divergence present in the muskmelon
germplasm.
3. To determine the association between yield and its component characters.
4. To study the direct and indirect effects of yield components on yield.
5. Molecular characterization in muskmelon germplasm by using SSR primers.