MSc

The present study entitled “Collection and characterization of unique
genotypes of nutmeg (Myristica fragrans Houtt.)” was carried out at the
Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara,
Thrissur with the objective to collect and characterize the unique nutmeg
accessions based on morphological and biochemical parameters.
Twenty one unique accessions possessing 13 unique characters were
identified and collected through an extensive survey throughout the nutmeg
growing tracts of Kerala. The unique accessions collected from diverse locations
of Kerala along with the two improved accessions identified in an earlier study
formed the material for the present study. Morphological characterization was
attempted using 18 qualitative and 31 quantitative parameters as per the nutmeg
descriptor. Fruits collected from these unique accessions were subjected to
biochemical estimation of constituents in rind, nutmeg and mace. The mace and
kernel volatiles were subjected to GC MS analysis.
The unique germplasm included yellow maced nutmegs which is a desirable
characteristic that is rarely spotted in the nutmeg family. Another unique tree with
rudimentary sterile seed / seedless nature was located which is an exception from
the normal. This accession had a good measure of fresh mace (9.74 g), mace oil
and oleoresin content. The double seeded nutmeg accessions DS-1and DS-2 may
be regarded as accessions having aberration in terms of mace and nut
characteristics, with a typical four halved fruit splitting nature and two seeds per
fruit. Monoecy is a very much preferred characteristic as nutmeg is usually
classified as dioecious in nature, but the two monoecious accessions namely MN-
1 and MN-2 had very less number of fruits with average quality mace and nut.
The two cluster fruited accessions had on an average three fruits per bunch and
four to eight fruits per cluster occasionally. Accession CF-1 had high nut andmace yield per tree among all the unique nutmeg accessions collected in the
present study. Among the low astringent nutmeg accessions, LA-2 adds
robustness towards further research in nutmeg for use in the value addition of
rind. The narrowly pyramidal (conical) shaped nutmeg accessions PT-1 and PT-2
had the least canopy spread. Grape nutmeg is another interesting unique accession
with numerous small sized fruits, thin mace and small nut.
Wild nutmeg (Myristica malabarica ) accessions had large brown velvety
fruits with yellowish orange coloured oblong mace. Oblong shaped nutmeg was
another interesting distinct feature noticed in the study. Another accession with
triangular shaped mace was spotted which possessed the second highest sabinene
content in kernel oil among all unique accessions. Small leaf type nutmeg labelled
SM-1 possessed dark green coloured narrow elliptic leaves with a nut and mace
yield comparable to cluster fruited nutmeg.
Among the quantitative tree characteristics, canopy spread was lowest in
narrowly pyramidal accessions. Small leaved nutmeg had smallest leaf
dimensions and leaf area was only half that of the normal nutmeg. Monoecious
nutmeg had significantly high measure of flower characteristics. Biochemical
characterization of volatile and nonvolatile contents of mace and nut revealed that
accession GT-1 had high kernel oil recovery, MN-2 had high kernel oleoresin
recovery and CF-1 had high fat content in kernel. Chemo profiling of the mace
and kernel volatiles identified thirty eight constituents. Among these, myristicin
,elemicin, sabinene and safrole were the major constituents. Highest myristicin,
sabinene, safrole and elemicin in mace oil were observed in GT-1, OB-2, LA-
1and MN-1. Highest myristicin, sabinene, safrole and elemicin in kernel oil were
observed in LA-2, MN-2, CF-1 and MN-1.
Based on qualitative tree, flower and fruit characters, twenty three unique
nutmeg accessions were grouped into twelve clusters at 60% similarity. The
similarities noticed were assessed through UPGMA (unweighted pair group
method with arithematic mean) method and a dendrogram was drawn accordingly
using NTSYS package 2.2. Similarity studies among unique accessions revealedthat majority of accessions had broadly pyramidal canopy architecture with
spreading branching pattern. Inflorescence noticed was axillary raceme in
majority, with the exceptional umbellate cyme inflorescence in monoecious,
double seeded and grape nutmeg accessions. Mid and late season flowering nature
was exhibited by majority of the unique accessions. Mace colour was
predominantly red with exceptions to yellow maced and wild nutmeg.
Monoecious nutmeg had three halved fruit splitting nature, while double seeded
nutmeg had four halved fruit splitting nature.
All the fruit characteristics were measured and put to analysis for
identification of sub groups among the 23 accessions using Univariate General
Linear model. Further a ranking technique was adopted to bring the different
characteristics present in the unique accessions into a comparative scaled value in
one dimension. Based on the pooled rank scores, five groups namely extra
ordinary, very good, good, moderate and heteroscedastic groups were obtained.
The measured variability for each of the characteristics that were prominent
among the five groups were listed as: leaf length (19.13%) and length of flower
(24.81%) in ‘Very good’ group; plant height with a CV of 45.12%, girth with a
CV of 75.27%, canopy spread N-S (38.98%)and E-W (40.39%), breadth of
flower with a CV of (11.74%) and breadth of perianth (36.36%) in ‘Good’ group;
leaf breadth (23.56%) and leaf area (26.99%)in ‘Moderate’ group; length of
perianth in ‘Heteroscedastic’ group. A concept diagram was developed for
utilizing the unique nutmeg accessions. All the unique accessions are worthy of
conservation. Apart from conservation value, SL-1 and LA-2 offer scope for value
addition of rind. Accession GT-1 and GT-2 are best suitable for ornamental
purpose. Accession CF-1 which possesses all the desirable features of an elite
nutmeg genotype can be commercially popularized as a variety.