Survey, characterization and evaluation of clove (Syzigium aromaticum (L) Merr. and Perry) accessions
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Date
2018
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Department of Plantation Crops and Spices, College of Agriculture, Vellayani
Abstract
The present study entitled “Survey, characterization and evaluation of clove
(Syzigium aromaticum (L) Merr. & Perry) accessions” was taken up with the
specific objective to characterize and evaluate clove accessions based on
morphological and biochemical parameters.
The Survey was carried out in the major clove growing plantations of
Trivandrum, Kollam and Pathanamthitta districts of Kerala and Kanyakumari
district of Tamil Nadu, as these districts harboured the major clove population.
Twenty varied accessions were tagged as BRC-1, BRC-2, BRC-3, BRC-4, MRC-
5, MRC-6, MRC-7, MRC-8, AMC-9, AMC-10, AMC-11, AMC-12, AMC-13,
MMC-14, MMC-15, BLC-16, BLC-17, BLC-18, MGC-19 and ANC-20 based on
the name of the estates/location from where the trees were identified. Twenty one
qualitative and thirty four quantitative characters were recorded. Qualitative
characters included tree, leaf, bud, flower, fruit and seed characters. Considerable
variation was noticed among the accessions for the qualitative characters namely
canopy shape, branching pattern, colour of young leaf, colour of mature leaf, leaf
lamina shape, leaf apex shape, bud forming season, bud clustering habit, bud size,
colour of hypanthium, petal colour, sepal colour, colour of stigma, fruit shape and
seed shape. Few characters like leaf arrangement, position of flower, colour of
peduncle, mature fruit colour, ripe fruit colour and seed colour were non variable
characters among the accessions evaluated. Bivariate analysis of major qualitative
characters revealed major association between canopy shape and branching pattern;
colour of young leaf and petal colour, sepal colour and colour of stigma; colour of
mature leaf and bud size; and fruit shape and seed shape. The multivariate
qualitative clustering using UPGMA method resulted in 13 clusters, at default 80%
similarity.
Quantitative characterisation of bud, flower, fruit, seed and quality
parameters summarised based on the descriptive statistics revealed wider range of
variability in number of inflorescence per m2 and single bud weight fresh and dry.
The quality parameters assessed among the accessions revealed eugenol as
the main constituent with a content range of 54.29 to 70.77%. GC MS analysis of
the bud oils of the elite clove accessions exhibited 25 constituents, the major being
p-eugenol, eugenyl acetate, β-caryophyllene, β-cubebene and α-humulene.
The principal component analysis undertaken reduced the thirty two
quantitative characteristics to two principal components accounting for 88.8% of
total variation. Stem girth at 45 cm height, and single bud weight, fresh and dry;
displayed high correlation with the first axis while number of inflorescence per m2
highly influenced the second axis indicating that these characters have an important
role in clustering of clove accessions. A score plot generated based on the first two
principal components using Minitab version 18 identified fourteen clusters. The
parallelism between qualitative and quantitative clusters resulted in intuitive
perceived quantitative characterisation, which tells the extent to which one can
conceive the quantitative characters of clove based on easily identifiable qualitative
characters.
The linkage of characters analysed based on the biplot of component
loadings revealed strong positive association between all the quantitative characters
measured except girth at 45 cm height, number of branches, number of
inflorescence per m2, single bud weight (fresh), single bud weight (dry) and fresh
bud yield per tree. A near zero correlation was observed between number of
inflorescence per m2 and single bud weight (fresh) and single bud weight (dry) as
indicated by the perpendicular of the vectors.
The results of the study indicated that by observing the qualitative characters
and the minimum data set characters in the bearing season, one can optimally sort
out the ideotype clove accessions. Identification of an ideotype using existing data
revealed accessions BRC-1, MRC-5, MRC-6 and BRC-3 as ideotypes and thus can
be suggested as elite accessions for further study and breeding work.
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