PhD

The present investigation on 'Morphological, biochemical and molecular
characterization in landraces of melon (Cucumis melo L.)' was carried out at the
Department of Olericulture and Centre for Plant Molecular Biology, College of
Agriculture, Vellayani during 1999-2002. Forty genotypes of Cucumis melo were
collected from Kerala and Tamilnadu regions. Twenty two morphological
characters viz., days to first male flower, node number of first male flower, days to
first female flower, node number of first female flower, sex ratio, vine length,
number of primary branches, number of secondary branches, internodal length,
leaf petiole length, leaf thickness, days to fruit harvest, fruit length, fruit girth,
fruit diameter, average fruit weight, dry matter content, fruits per plant, seeds per
fruit, 1000 seed weight, yield per plant and fruit shape and colour were used in
this study. The genetic parameters, correlation and path coefficients were studied
and the genetic divergence worked out using 02 statistics. The genotypes were
also characterized by biochemical method (SDS-PAGE) and molecular techniques
(RAPD analysis).
Morphological studies showed significant differences among the forty
genotypes for all the twenty one characters. CM 32 collected from Manjapra was
the top yielder. The highest PCV and GCV were observed in yield per plant
followed by average fruit weight and fruits per plant. High heritability coupled
with high genetic gain was obtained for yield per plant followed by average fruit
weight and fruits per plant.
Sex ratio, vine length, number of secondary branches, internodal length,
.frJ;lit, length, aye rage fruit weight, fruits per plant and seeds per fruits were
d.". I, .! !. •
positively correlated with yield per plant, whereas node number of first female
." 1\..'• . .
flower wasnegatively correlated, with yield. per plant. Path analysis revealed
tl u. \..1:, l .. ', ' " _. . " ,' .
. "'pr~age fruit weight and fruits per plant as primary contributions to yield.
nu -In' 02 analysis, - the' forty genotypes were grouped into twenty clusters.
Max ,It "\ I '\..!, \ I j , • l , ~) I .

CM 5 (dessert melon) genotypes came under cluster XIV. CM 4 and CM 38
(slicing and culinary melon) genotypes came under cluster XVI. The dessert types
formed a separate cluster and the slicing type melon fell along with culinary
melon genotypes. The 02 analysis differentiated culinary types of melon from
dessert types.
Total soluble protein yield extracted from the forty genotypes of Cucumis
melo seeds ranged from 0.858 to 3.200 ug seed". Maximum of 18 bands were
observed in CM 7 and CM 40. Least number of 5 bands was present in CM 2.
The dendrogram, showed two major clusters viz., cluster A and cluster B. Cluster
B had only one dessert genotype, CM 2. Cluster A had all other culinary melon
genotypes including slicing type CM 4. Cluster A was further grouped into four
subclusters. A similarity index within major cluster A showed 37.5 per cent
between CM 1 and CM 27. A similarity index of 13.3 per cent present between
CM 2 (cluster B) and CM 1 (cluster A). Seed protein results were not correlated
with 02 analysis, geographical location and morphological characters like fruit
shape and colour.
DNA isolated from the forty genotypes of Cucumis melo were subjected to
~PO analysis. Out of the 46 decamer primers screened for RAPO analysis, 31
could produce amplification. Totally 103 bands (average 2.24 bands per primer)
were generated by thirty one primers, of which 96.12 per cent (99 bands) were
polymorphic. Four bands (3.88 %) were monomorphic. Seven primers showed
high level of polymorphism. Finally, four best promising primers viz., OPA-Ol,
OPA-08, OPB-12 and OPB-20 were used for RAPO analysis of 40 Cucumis melo
genotypes. These primers yielded ,29 scorable bands with an average of 7.25
bands per primer. Dendrogram expressed two major clusters were formed viz.,
cluster A and cluster B. Cluster B had CM 2 and CM 5 of dessert genotypes.
Similarity index was 75 per cent between CM 2 and CM 5 genotypes. Cluster A
was again subclustered into six groups. CM 4 (slicing melon) was grouped along
with culinary melon genotypes. 02 analysis and protein results of slicing types
were in line with RAPO results. Considering all genotypes RAPD analysis does

not agree with geographical location and morphological characters like fruit shape
and colour.
In the present study, characterization of forty genotypes of Cucumis melo
using morphological, biochemical and molecular basis (RAPD marker analysis),
the last method gave a perfect differentiation of dessert melon from culinary
melon which is also agreeable with morphological characterization.