Studies on heterosis and combining ability analysis for yield, yield contributing and fibre quality traits in BT cotton (BG I) (Gossypium hirsutum L.)

Introduction

Cotton is a member of the Malvaceae family, specifically the Gossypium tribe. Currently, Gossypium contains 50 species in which only four species are cultivated, namely Gossypium arboreum, Gossypium herbaceum, Gossypium hirsutum and Gossypium barbadense. The first two species are diploid (2n=26) and belong to the Old World. They are also referred to as Asian cotton because they are grown in Asia. The two remaining species are tetraploid (2n = 52) also known as New World cotton. G. hirsutum is also known as American cotton or upland cotton, whereas G. barbadense is referred to as Egyptian cotton, Sea Island cotton, Peruvian cotton, or quality cotton. G. hirsutum is the major species, accounting for around 90% of global production. Perhaps India is the only country in the world where all four cultivated species are grown commercially. The world's most extensively grown cotton species is Gossypium hirsutum, also known as upland cotton or Mexican cotton. Gossypium hirsutum is divided into multiple kinds or crossbred cultivars, each having a different fibre length and tolerance to diverse growth conditions. G. hirsutum L. (American cotton) and G. barbadense L. (Egyptian cotton) are known for their high fiber quality. Gossypium hirsutum accounts for 99.9% of hybrid cotton in India, and all current Bt cotton hybrids are G. hirsutum or interspecific hybrids with G. barbadense.

Materials and Methods

The experimental material constituted thirty one cotton genotypes acquired from Cotton Research Station, Nanded, VNMKV, Parbhani (Table 1). The sowing was done with spacing 120 x 45 for hybrid and 60 x 30 for parents with a plot size of 2.4 x 6 m.sq. The seeds were sown on 16 th July, 2022-23 these genotypes were sown in Randomized Block Design with two replications. five competitive plants per genotype in each replication were selected randomly and observations are recorded.

Statistical Analysis

The mean values of each genotype were employed for statistical analysis. The combining ability was estimated as per the procedure given by Kempthorne (1957) [5] . ANOVA was calculated by using formula given by Panse and Sukhatme (1961). Line x Tester analysis was carried out as suggested by Arunachalam (1974).

Results and Discussion

Analysis of variance

Analysis of variance for Line x Tester for different traits of cotton genotypes are indicated in table 2. Analysis of variance revealed that all the genotypes differed significantly high for all the characters viz, days to 50 per cent flowering, days to maturity, plant height, number of sympodia per plant, number of bolls per plant, boll weight, seed cotton yield per plant, seed index, lint index, ginning percentage, upper half mean length, fibre fineness/ micronaire, fibre strength, uniformity ratio, number of aphids/3 leaves, number of jassids/3 leaves, number of thrips/ 3 leaves, number of white fly/3 leaves, trichome density, leaf thickness (Table 2). Twenty cross combinations obtained by crossing five lines and four testers into line x tester (L X T) analysis. The significant differences were observed among traits.

Estimation of heterosis

The genetic characteristics for the characters under study includes standard and better parent heterosis as shown in the Table 3. In the present investigation large differences in mean values for all the traits were observed. Out of twenty crosses, the crosses the crosses showed highest and desirable significant [1] , Usharani et al. (2015) [11] , Monicashree et al. (2017) [8] , Bilwal et al. (2018) [2] and Islam et al. (2021) [4] .

Estimation of combining ability

Combining ability plays an important role in crop breeding. The knowledge on combining ability will assist the breeder develop a future breeding program to utilize both additive and nonadditive components of genetic diversity in the material. Estimation of combining ability were calculated among all characters under investigation (Table 4). Combining ability is the ability of a genotype to pass on desired genotypes to its offspring during the hybridization process. General combining ability refers to a genotype average performance in a series of cross combinations involving a group of genotypes. It is particular to the collection of lines and the testing environment. Specific combining ability is the performance of a specific cross combination reported as a deviation from the population mean. The present findings are in confirmation with results of Kumar et al. (2014) [7] , Srinivas et al. (2014) [9] , Solanke et al. (2015) [10] and Kencharaddi et al. (2015) [6] .

References

1. Ashokkumar K, Kumar KS, Ravikesavan R. Heterosis studies for fibre quality of upland cotton in line x tester design. Afr J Agric Res. 2013;8(48):6359-6365.
2. Bilwal BB, Vadodariya KV, Lahane GR, Rajkumar BK. Heterosis study for seed cotton yield and its yield attributing traits in upland cotton (Gossypium hirsutum L.). J Pharmacogn Phytochem. 2018;7(1):1963-1967.
3. Chakholoma M, Nimbal S, Sangwan O, Mor VS, Jain A. Studies on economic heterosis for yield and fibre quality traits in American cotton (Gossypium hirsutum L.). Ekin J Crop Breed Genet. 2022;8(1):61-69.
4. Islam AA, Era FM, Khalequzzaman MF, Chakrabarty S. Estimation of heterosis in hybrids of upland cotton (Gossypium hirsutum L.) for seed cotton yield and related traits. J Adv Plant Sci. 2021;1:1-12.
5. Kempthorne O. An Introduction to Genetic Statistics. New York: John Wiley & Sons;1957. p. 453-471.
6. Kencharaddi HG, Hanchinal RR, Patil SS. Studies on combining ability in inter-heterotic group derived cotton hybrids for lint yield and its components. Res Environ Life Sci. 2015;8(3):451-456.
7. Kumar KS, Ashokkumar K, Ravikesavan R. Genetic effects of combining ability studies for yield and fibre quality traits in diallel crosses of upland cotton (Gossypium hirsutum L.). Afr J Biotechnol. 2014;13(1):119.
8. Monicashree C, Balu AP, Gunasekaran M. Heterosis studies for yield and fibre quality traits in upland cotton (Gossypium hirsutum L.). Int J Pure Appl Biosci. 2017;5(3):169-186.
9. Srinivas B, Bhadru D, Rao MVB, Gopinath M. Combining ability studies for yield and fibre quality traits in upland cotton (Gossypium hirsutum L.). SABRAO J Breed Genet. 2014;46(2):313-318.
10. Solanke A, Deshmukh SB, Mhasal GS, Marawar MW. Heterosis and combining ability in genetic male sterility based diploid cotton hybrids for yield, yield component, fibre quality characters and oil content. Electron J Plant Breed. 2015;6(1):150-156.
11. Usharani KS, Vindhiyavarman P, Balu PA, Boopathi NM. Heterosis studies for fibre quality traits in diallel crosses of upland cotton (Gossypium hirsutum L.). The Bioscan. 2015;10(2):793-799.