PhD

An investigation on morpho-anatomical and molecular characterization
of Dendrobium varieties was conducted in the Department of Pomology and
Floriculture, College of Agriculture, Vellayani during 1999-2001.
Fifteen Dendrobium varieties of near flowering size plants were
evaluated for thi'~ growth morpho-anatomical and molecular characterization
and another nine Dendrobium varieties of three year old plants were evaluated
for the morpho-anatomical characters.
The fifteen Dendrobium varieties differed significantly for the
growth parameters viz., rate of increase in shoot girth, increase of leaf area
of the shoot, leaf area at completion of leaf unfurling, leaf area at
inflorescence emergence, leaf area at first flower opening, days taken from
inflorescence emergence to first flower opening and days taken from
inflorescence emergence to full bloom. Significant varietal difference
were observed among the fifteen varieties for shoot length, shoot girth,
internodal length of shoots, number of nodes per shoot, length and width
of leaves, basal internodal length of stalk, number of flowers, length and
width of flowers, root thickness, cortex thickness, number of layers in
velaman, leaf thickness, number of stomata in the adaxial and abaxial
surface of leaf, petal thickness and thickness of pigmented layers.
The nine Dendrobium varieties (three year old plants) evaluated
separately showed significant difference for shoot length, shoot girth,
internodal length of shoots, number of nodes per shoot, length and width
of leaves, number of flowers, length and width of flowers, root thickness,
number of layers in cortex and velaman, leaf thickness, number of stomata
in adaxial and abaxial surface of leaf, petal thickness and thickness of
pigmeted layers.
High GCV and PCV were observed for petal thickness followed by
number of flowers, while high heritability was observed for petal

thickness and length and width of flowers. Petal thickness, number of
stomata in the abaxial surface of leaves and number of flowers exhibit
high heritability along with genetic advance.
The shoot length showed significant positive genotypic correlation
with shoot girth, number of nodes per shoot, number of laminate leaves
per shoot. length and width of the leaves. The number of flowers showed
positive correlation with length and width of flowers. High genotypic
correlation was observed between the length of inflorescence and number
of nodes per shoot as well as the width of leaves. Significant positive
environment correlation was observed between shoot length and number
of nodes per shoot, length of leaves, width of leaves.
The genetic diversity among the fifteen Dendrobium varieties was
studied using Mahalanobis 02 analysis. The fifteen varieties were
grouped into three clusters.
The qualitative characters of leaf and flowers were analysed for all
the 24 Dendrobium varieties used in the investigation.
Molecular characterization of fifteen Dendrobium varieties
evaluated in the experiment I was carried out using RAPD technique.
The ON A yield varied from 120 to 225 ng/ ml. The primers OPA-19,
OPB-02, OPB-04 and OPB-I0 yielded good resolution bands out of 40
decamer primers tested. These primers amplify 44 RAPD markers of
which 39 were polymorphic and five were monomorphic. The Similarity
Coefficients value of the varieties ranged from 0.2667 to 0.8824. The
genetic distance ranged from 0.1176 to 0.5806. The fifteen varieties got
divided into six clusters on drawing a vertical line in the Dendrogram at a
distance of 0425.
A detailed descriptive blank of 24 Dendrobium varieties evaluated
in the investigation was prepared.