The breeding material for the present study comprised five parents/varieties and their ten F2 progenies of cotton (Gossypium hirsutum L.). Experimental trial was conducted at the Cotton Research Institute, Tandojam in randomized complete block design (RCBD) with three replications during 2020. The seed of ten intra-hirsutum ten F2 population and their ten parents was sown in the field by diblling method .Three seeds per hill were dibbled, however after 15 days, seedling were thinned to one per hill to ensure uniform and reduced plant competition for optimum plant growth and development. The distance between plant to plant was kept at 30cm whereas row to row at 75cm. All the agronomic practices were done at proper time. The inputs like fertilizer, irrigation and insecticides were applied as and when required. The parental varieties involved in developing F2 hybrids/progenies are listed in table.1.
Collection of data
1. Days to 1st boll formation
Number of days was counted from planting to the appearance of first boll formation.
2. Days to 1st boll opening
The number of days was recorded from sowing date to 1st boll opening.
3. Bolls formation after 90 days of sowing
Earliness percentage of boll formation was recorded after 90 days of sowing from the total bolls formed at 90 days.
4. Plant height (cm)
The final plant height was measured from index plant in centimeters
5. Sympodial branches plant-1:
In cotton, buds generally emerge from axils of leaf. The upper ones are called axillary buds and lower ones as extra axillary bud. The extra axillary bud gives rise to sympodial branches which bears fruits. Number of sympodial branches per plant was counted per plant from tagged plants at the time of maturity.
6. Boll plant-1:
The total number of bolls were counted from tagged plants and recorded as number of productive bolls.
7. Bolls weight (g):
Boll size per plant was calculated by dividing the seed cotton yield per plant with the number of productive bolls per plant. The average boll weight was calculated by the formula given below
Boll weight (g) = weight of seed cotton yield per plant (g)
Number of bolls per plant
8. Seed cotton yield plant-1 (g):
At maturity time, mature bolls were picked in paper bags and seed cotton was kept separately from each plant. Picking was done after 10: A.M. when the due was over. Weight of seed cotton yield per plant was taken in grams with the help of electronic balance in the laboratory.
9. G.O.T (%):
Ginning outturn percentage is the ratio of lint to seed cotton sample after ginning. The samples were first dried under the sun then ginned with electric saw gin machine. The ginning outturn percentage (G.O.T.) was calculated by using the following formula
G.O.T % = Weight of lint (g) x 100
Weight of seed cotton (g)
10. Staple length (mm):
Staple length or fiber length is the most important quality parameter in cotton. Four samples of lint from each plant were run in the digital fibro graph and the automated measurements from the screen were recorded in millimeters.
The present research was carried out to determine genetic parameters of some quantitative traits in intra-hirsutum crosses of upland cotton (Gossypium hirsutum L.) through genetic analysis developed by Falconer (1889). ANOVA was done according to statistical procedures developed by Gomez and Gomez (1984).
The genetic parameters studied were:
- Genetic coefficient of variability (G.C.V)
- Genetic variance (δ2g)
- Heritability percentage in broad sense (h2)
- Genetic Advance (GA)
The genetic parameters for all the characters were determined as under:
1. Mean = X/n
2. Variance (s) = ∑ (x2) - ∑ (x)2 ⁄ n
3. Standard deviation (SD) = √ s2
4. Genetic coefficient of variability (G.C.V) = √ σ2 g x 100
5. Genetic variance (δ2g) = δ2F2 – δ2e
6. Environmental variance (δ2e) = (δ2P1 + δ2P2)
7. Heritability percentage (h2%) = δ2 g x 100
8. Genetic advance (G.A) = k x (H) x SD
SD = Phenotype standard deviation
K = Constant for selection difference at 10% selection intensity
δ2e = Environmental variance
δ2g = Genetic variance
δ2P1 = Variance of parent one
δ2P2 = Variance of parent two
H = Heritability coefficient
h2% = heritability percentage in broad sense
GA = Genetic advance
GCV = Genetic coefficient of variability
S2 = Variance
∑ = Sigma (latin alphabetical word) means summation.
X = mean
X = variable.