Cotton Genomics and Genetics 2015, Vol.6, No.1, 1-6
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The PC1 contribution was highest (18.5%) amongst
all other (PCs) towards the variability, while Pc II,
PCIII, PC IV and PC V contribution was 15.6%,
10.5% and 9.7% respectively. The traits like days to
first f, days to first flowering CLCuD, Nodes to 1st
fruiting branch, GOT and staple length on PC1
exhibits considerable positive factor loading on the
other hand plant height, monopodia per plant and fiber
fineness had maximum negative loading. PCII
contributed significant positive loadings for plant
height, monopodia per plant and sympodia per plant
while had significant negative loading for GOT, fiber
fineness and CLCuD. In PC-III the variation among
the genotypes was due to Nods per plant, staple length
and CLCuD with significant positive loading whilst
fiber fineness days to first seedling and days to first
fruiting had significant negative loadings. PC IV
elucidated by the variation among genotypes for staple
length, boll weight and monopodia per plant with
significant positive loadings, while sympodial per
plant, CLCuD and nodes per plant showed significant
negative loading. Similarly in PC V all traits had
positive loading however boll weight, monopodia per
plant and CLCuD were the major contributor towards
the total variability with significant positive loading.
A PC bipolt figure 1 showed that genotypes and
variables are super imposed on plot as vectors. The
distance of each variable with respect to PC-1 and
PC-2 exhibited share of these variables in the diversity
of the genotypes used. The biplot figure depicted that
as whole days to 1stsquare, flower and monopodia per
plant share were maximum towards variability in
germplasm.
Cluster Analysis
By using cluster analysis 159 exotic genotypes were
grouped into 6 clusters on the basis of various traits
(Table 4). That cluster I, II, III, IV, V and VI
Comprised of 25, 18, 23, 46,27 and 20 genotypes
respectively (Name of genotypes not shown). The
genotypes in the first cluster represent reasonable
values for days to first squaring, flowering, sympodial
branches per plant, staple length and fiber fineness
while for other traits selection cannot be made in this
cluster. The members of 2nd cluster exhibited lower
values for CLCuD, fiber fineness and GOT% whilst
plant height, staple length and sympodia per plant
showed higher values. The cluster III was
characterized by genotypes having maximum GOT,
staple length and fiber fineness. Cluster IV showed
reasonable values for CLCuD, GOT and staple length.
Cluster V was found suitable for only staple length
while genotypes in cluster VI had maximum values
for plant height and sympodia per plant. The first two
principle components contributed almost 34.1 % in
total variance. Among all clusters not a single cluster
exhibited obvious separation.
Figure 1 Biplot between PC-1 and 2 showing contribution of various traits in variability among different genotypes
