Cotton Genomics and Genetics 2015, Vol.6, No.1, 1-6
5
calculated in grams (g). Average boll weight in grams
(g) was calculated by dividing the total seed cotton
yield per plant with the total number of bolls of that
plant. Mean boll weight of each plant was taken in
grams (g) and then overall averaged. Seed cotton was
picked when the crop was mature and recorded as
Kg/plot and extrapolated to Kg/hectare.
3.4 Cotton leaf curl virus (CLCuV) disease
incidence (%) methodology
CLCuV disease incidence (%) and the reaction of the
cultivars was determined using the disease scale (Table
5) described by Akhtar et al. 2010 and Farooq et al.
2011. Then, % of CLCuV disease incidence was
calculated by using the following formula;
Table 5 Rating scale for cotton leaf curl virus (CLCuV) symptoms
Symptoms
Disease rating
y
Disease index (%)
z
Disease reaction
Absence of symptoms.
0
0
Immune
Thickening of a few small veins or the presence of leaf enations
on 10 or fewer leaves of a plant.
1
0.1~ 1.0
Highly resistant
Thickening of a small group of veins.
2
1.1~5.0
Resistant
Thickening of all veins but no leaf curling.
3
5.1~10
Moderately resistant
Severe vein thickening and leaf curling on the top third of the plant. 4
10.1 ~ 15
Moderately susceptible
Severe vein thickening and leaf curling on the half of the plant.
5
15.1 ~ 20
Susceptible
Severe vein thickening, leaf curling, and stunting of the plant
with reduced fruit production.
6
>20
Highly susceptible
CLCuV disease incidence (%) = Sum of all disease
ratings/total number of plants ×16.16
3.5 Statistical Analysis:
The data were subjected to analysis of variance
(ANOVA) using the MSTAT-C package (Russell, D.
Freed, Michigan State University, USA, 1984).
Heritability in broad sense was estimated according to
the technique of Burton and De Vane (1953). All
correlations (phenotypic and genotypic) were
computed following the statistical technique
prescribed by Kwon and Torrie (1964). Genotypic
correlations were tested following the method of
Lotherop et al. (1985). Statistical significance of
phenotypic correlations was determined by T-test as
described by Steel and Torrie (1984). Path coefficient
analysis was done following to the method suggested
by Dewey and Lu (1959).
4 Conclusion
Positive correlation, high heritability and positive
direct effects of sympodia per plant, bolls per plant
and plant height with seed cotton yield is indicative
that selection for these traits may be practiced to
enhance seed cotton yield.
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