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Method for establishing a minicore collection in finger millet (Eleusine coracana gaertn.)

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Title Method for establishing a minicore collection in finger millet (Eleusine coracana gaertn.)
 
Creator T. M, Ramanappa
 
Contributor A, Seetharam
 
Subject genetics, sampling, developmental stages, planting, millets, selection, germplasm, sets, rapd, crops
 
Description An effort has been made in the present investigation to develop a representative
minicore subset of a large global collection using vast database on geographical origin,
morphological and agronomic traits. In order to arrive atmost representative minicore
set, three grouping principles such as Mahalanobis distance, Euclidean distance and Chisquare
distance, two sampling proportions (15% and 20%) and two sampling strategies
(random and preferred) in various combinations were tried. In all, 12 minicores were
formed and compared for the diversity present in each one of them for various characters
with the original core set. The important statistics such as Standardized Mean Difference
(SMD%), Variance Difference (VD%), Coincidence Rate (CR%) and Variable Rate (VR%) were
employed to identify the most representative minicore set. This resulted in selection of
one best representative minicore formed following Chi-square genetic distance along with
preferred sampling strategy at 20 per cent proportion..
The evaluation and characterization of most representative minicore set revealed
the presence of significant amount of variation for almost all the important agronomy
characters such as plant height, number of tillers per plant, days to 50 per cent
flowering, number of fingers per ear, finger length, days to maturity, ear weight, grain
weight, straw weight and harvest index suggesting that the superior parents for the traits
of economic importance could be chosen for use by breeders. Wide range of variation was
also observed for physiological characters viz., leaf area, leaf area index, specific leaf
area, leaf area duration, total dry matter and its partition, photo-periodic response, net
assimilation rate and moderate variability for vein and stomatal frequency, delta 13c
analysis, leaf nitrogen content and rate of water loss. The strong positive correlations
among agronomic and physiologic traits were observed and these traits may be under
control of co-adapted gene complexes. All these traits were well conserved in the
minicore set. A high magnitude of variability was observed for photoperiodic response,
based on which the minicore accessions could be grouped in two major groups; photo
insensitive and sensitive types. The identification of photo insensitive accessions is
important in breeding of varieties suitable for growing in both rainy and post rainy
seasons without affecting the crop duration.
Principal component analysis of quantitative traits revealed the distribution of
variation among several characters and no single character explain the variation to its
maximum. Molecular diversity analysis carried through RARD and ISSR markers indicated
that slightly higher polymorphism for RAPD marker than ISSR and the dendrograms of both
markers exhibited similar trends in terms of genetic relatedness of the accessions.
Principal co-ordinated analysis explained the existence of genetic diversity in the
evaluated minicore and ISSR markers are found to be more useful for diversity analysis in
finger millet compared to that of RAPD markers.
The minicore set formed could perform the important role of working collection
maintained by the breeders at various centers in India. The minicore because of its
reduced size and still harboring very large diversity could serve as most suitable material
for further exhaustive evaluation for identifying accessions useful in varied crop
improvement programmes.
 
Date 2016-05-27T14:22:33Z
2016-05-27T14:22:33Z
2011-11-18
 
Type Thesis
 
Identifier Th-9565
http://krishikosh.egranth.ac.in/handle/1/66387
 
Language en
 
Format application/pdf
 
Publisher University of Agricultural Sciences, Bengaluru