GENETIC DIVERSITY IN UPLAND COTTON (Gossynium hirsutum L.)
GENETIC DIVERSITY IN UPLAND COTTON (Gossynium hirsutum L.)
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Date
1998-03
Authors
KLASSOU, Celestin
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Abstract
Two hundred and fourty seven genotypes of upland cotton were grown at Maroua and
Garoua (Cameroon), and Samaru (Nigeria), in 1994 to (i) investigate the nature and extent of
their genetic diversity using Principal Component and Cluster Analyses, (ii) assess the relative
contribution of different traits to their total variation, and (iii) determine the relation between
the clustering patterns and the geographic distribution of these accessions.
A 16 x 16 partially balanced lattice experimental design, with four replicates, was used
for this study. Plots consisted of single rows 5m long, spaced 1m apart at Maroua and Garoua,
and 0.91m at Samaru with a plant to plant spacing of 0.40m. Data were collected on five
competitive plants, wherever possible, for 25 agronomic and fibre technology traits. Analysis
of variance for each trait was performed on plot mean basis.
In the combined analysis of variance across locations, all the upland cotton genotypes
were significantly different for all the traits evaluated. The location x genotype effects were
highly significant for all the traits measured and their patterns varied appreciably over
environments, indicating differential response of different traits in varying environments.
At each location, significant variability for all the traits observed was also found among
the genotypes of upland cotton selected. The seed cotton per plant on average was low at Samaru
(43.5g), presumably due to late planting period, medium at Maroua (70.6g), and high at Garoua
(I99g).
Simple linear correlations, principal component and cluster analyses were performed on
adjusted treatment means. At Samaru, seed cotton per plant was positively associated with
reproductive traits, boll number, number of flowers per plant, but negatively correlated with
(lays to first and 50% flowers opening (presumably due to an important shedding of young
capsules), and fibre length. At Maroua coefficients of correlation were moderate.
At Garoua strong associations were observed between seed cotton yield, plant height,
number of monopodia and sympodia, flower and boll number, percent fibre and 2.5% Span
Length.
Two-dimensional scatter diagrammes displayed results of the principal component
analyses. There was a poor resolution of individuals into groups due to the fact that the two
principal components captured only about 30% of the total variation. Two large groups were
formed. All genetic materials originating from African countries grouped together and showed
good adaptation to the environments at the test sites.
The cluster arrangements delineated more precisely the individuals into 8, 7, and 6
groups at Samaru. Maroua, and Garoua, respectively. Despite some discrepancies, in general.
cluster patterns were in agreement with pedigree information
The intercluster divergence measured by the Mahalanobis' D distance varied from 1.8
to .3.8, indicating a moderate to low degree of diversity within the genetic materials studied at
each location.
Description
A thesis submitted to the Postgraduate School,
Ahmadu Bello University in partial fulfillment of
the requirements for the degree of Master of Science
in Crop Breeding
Department of Plant Science
Faculty of Agriculture, Ahmadu Bello University,
Zaria, NIGERIA
March, 1998.
Keywords
GENETIC,, DIVERSITY,, UPLAND,, COTTON,, (Gossynium hirsutum L.).