MSc

The research programme entitled ‘Morphological and molecular
characterization of Cattleya hybrids’ was carried out in the Department of Floriculture
and Landscaping, College of Agriculture, Vellayani, Thiruvananthapuram during the
period 2021-2022 to evaluate the performance of twelve Cattleya hybrids based on
growth and flowering attributes and to characterize them using morphological
descriptors and molecular markers.
The analysis of variance revealed significant differences in 12 genotypes for
all of the studied morphological characters, with the exception of plant height, such as
the number of shoots per plant, number of leaves per pseudobulb, length and width of
the largest leaf, and number of days from leaf emergence to maturity.
Out of the 12 Cattleya hybrids, flowering was observed in ten hybrids viz.,
Rth.Burana Beauty, Rlc.Taichung Beauty, Rlc.Mahina Yahiro, Rlc.Irene Dopkin,
C.Aurantiaca x Netrasiri Beauty, Rlc.Petch Wangnam Khiew, Rlc.Morning Stars, Rlc.
Haadyayi Delight x Mary Song, Rlc.Memoria Anna Balmores and C.Tipo during the
experiment.
Significant varietal differences were observed among the ten genotypes with
respect to the floral characters studied.
Variance component analysis revealed that highest PCV and GCV was
observed for number of shoots per plant and minimum for plant height among
morphological characters.
Maximum variability both at the phenotypic and genotypic level was observed
for the inflorescence number per pseudobulb followed by flower number per peduncle
among floral characters
High heritability values were recorded for the floral characters viz., length and
width of petal and dorsal sepal width followed by flower length.
High heritability with genetic advance was observed for petal and sepal width
followed by inflorescence number per pseudobulb.
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Flower width, length and width of petal, sepal and lip had significant positive
genotypic correlation with length and width of the largest leaf. Flower number per
peduncle exhibited positive correlation with plant height and number of leaves per
pseudobulb showed negative correlation with flower width, petal, sepal and lip length
and width.
Plant height had significant positive phenotypic correlation with length and
width of the petal and length of the largest leaf. Flower number per peduncle showed a
significant negative correlation with flower length and width. The length of flower
had significant positive correlation with width of the flower, which is an important
attribute of cut flower selection.
Low values of environmental correlation coefficient due to environmental
effect were estimated for most of the characters studied.
The genetic diversity among the genotypes was studied using ‘Average
method’ and ‘Euclidean Distance measures’. The genotypes were clustered into three
groups based on morphological and floral quantitative characters.
Maximum inter cluster distance was observed between the clusters C2 and C3
and minimum distance between C1 and C3. So selection of parents from the clusters
C2 and C3 will be very effective in hybridization.
Four hybrids viz., Rlc.Morning Stars, Rlc. Haadyayi Delight x Mary Song,
Rlc.Memoria Anna Balmores and C. Tipo recorded high scores based on scoring
given by DUS guidelines.
Molecular characterization of 12 Cattleya genotypes were carried out using
ISSR primers.
DNA yield varied from 0.776 ng/µl to 27 ng/µl. Out of the 97 amplicons
obtained, 96 were polymorphic and one was monomorphic.The twelve genotypes
were divided into four clusters at similarity coefficient of 0.65.
The clusters formed by morphological and molecular characterization grouped
the genotypes C. Chocolate Drops Volcano Queen and C.Aurantiaca x Netrasiri
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Beauty in the same cluster. The genotypes in the various clusters were nearly identical
in terms of morphology and genetics.
High petal and sepal width which are good floral attributes was observed for
the genotype Rlc.Petch Wangnam Khiew. C. Tipo was floriferous (25 flowers per
plant per year) followed by C. Aurantiaca x Netrasiri Beauty (20 flowers per
plant per year) compared to the other hybrids. All other hybrids exhibited
seasonal variation in flower production. So Rlc.Petch Wangnam Khiew, C. Tipo
and C. Aurantiaca x Netrasiri Beauty may be selected as parental genotypes with
good floral attributes.