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Studies on
polymorphism in some provenance collections of
Azadirachta indica A. Juss.
by
Sudhir Kumar Kaura
(An abstract from the thesis
submitted to the
CCS Haryana Agricultural University Hisar, Haryana, India
in partial fulfilment of the requirements for the degree of
Doctor of Philosophy in the subject of Genetics)
Title
of thesis: Studies on
polymorphism in some provenance collections of Azadirachta indica A.
Juss.
Full
name of degree holder: Sudhir Kumar Kaura
Title
of degree : Doctor of
Philosophy
Name
and address of major advisor: Prof. J. B. Chowdhury, Formerly Vice-Chancellor, G. B. Pant University
of Agriculture and Technology, Pantnagar, Uttaranchal Pradesh
Degree
awarding university/institute : Chaudhary Charan Singh Haryana
Agricultural University, Hisar-125 004, India
Year
of award of degree: 2001
A. D.
Major
subject: Genetics
Total
number of pages in thesis: approximately 412
Number of words in abstract: approximately 652
Keywords: neem, Azadirachta indica,
azadirachtin, diversity, conservation, callus, fingerprinting, heritability,
oil, provenance, RAPD, stability, viability
Two hundred and twenty one germplasm
accessions of neem (Azadirachta indica) from nine states of India
(Haryana, Rajasthan, Delhi, Himachal Pradesh, Uttar Pradesh, Panjab, Karnataka,
Tamil Nadu and Maharashtra) were studied for all or some of the following
aspects viz. tree architecture, endocarp morphology, seed viability, provenance
evaluation through growth of seedlings
in nursery conditions; and oil content, fatty acid profile, protein content and
azadirachtin content of seeds. In addition, thirteen local trees were taken up
for studying leaf morphology and tissue culture experiments. Statistically
significant differences (both within and between populations) were observed for
most of the morphological, biochemical and growth characteristics under study.
Considerable variation was also recorded
within and between provenances in trees surveyed in Haryana and adjoining areas
with respect to tree architectural parameters and their linear associations. Of
136 trees studied, 58 candidate plus trees (CPTs) for agroforestry, 45 CPTs for
seed production as well as agroforestry and 47 CPTs for seed production were
marked. Multiple regression equations (with very high level of goodness of fit
of the regression line) based on the available tree architectural parameters,
could be developed for predicting values of clear bole, unforked height and
ratio of unforked height and height. Highly divergent trees could be identified
for combination of important tree architectural parameters with the help of
principal component analysis.
Genetic parameters were studied for
endocarp morphological characteristics. Moderate to high estimates of genotypic
coefficient of variation, broad sense heritability and genetic advance were
obtained for endocarp weight and seed weight, indicating high level of genetic
variability and potential of improvement for these traits through selection.
Statistically significant genotypic correlations were observed between
characteristics like endocarp length, endocarp weight, seed weight in some of
the populations suggesting the possibility of enhanced correlated response upon
indirect selection for these morphological characteristics. Separation of the
genotypic correlation coefficient into components of direct and indirect
effects was done using path coefficient analysis for seed weight and ratio of
seed weight and endocarp weight. Seed weight was directly and indirectly
affected by both endocarp weight and endocarp
coat weight in most of the provenance collections. Ratio of seed weight and
kernel weight was directly and indirectly affected by all the morphological
characteristics of endocarp in all the provenance collections under study. Using
multivariate analyses (D2 analysis; hierarchical cluster analysis;
and principal component and principal factor analysis) it was possible to
delineate highly divergent samples with respect to endocarp morphological
characteristics. Clustering pattern found to have partial dependence on
geographical location of the germplasm accessions. Some similarity was observed
in clustering pattern obtained by different multivariate techniques. Temporal
stability for the endocarp morphological characteristics was quite high except
for 20 seed weight, for which stable genotypes could be identified. Likewise,
for seed oil content significant genotype-environment interaction was observed
and differences were observed with respect to temporal stability.
Fatty acid profile (stearic acid and oleic
acid) of seeds showed a strong association with geographical position and
agroclimate of the sampling sites while no geographic association was found for
seed oil content. Viability of seeds appeared to be affected by the oil content
of seeds rather than fatty acid profile. Callus cultures could be raised from
axillary bud, shoot tip, leaf, and mature seed explants. In vitro
production of azadirachtin was recorded in callus cultures raised from axillary
bud explants. Shoot regeneration could be obtained from callus cultures
developed from axillary buds and mature seed. Protocol for fingerprinting the
neem genotypes using RAPD (Random Amplified polymorphic DNA) technique has been
standardised and preliminary investigations with 15 genotypes and pooled DNA
samples of 5 populations indicated within and between population genetic
variability.
Morphological, physiological and molecular
marker data revealed ample genetic diversity in neem at population and
individual levels. Clinal variation observed in seed biochemical
characteristics like stearic acid and oleic acid suggests that for germplasm
conservation attention should be paid to populations according to latitudinal
and longitudinal gradients.
Major Advisor
Head of the Department Signature of degree holder
----------------------------------------------------------------------------------------------------------
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