Unravelling Genetic Architecture and Phenotypic Diversity for Seed Cotton Yield and Associated Traits in Upland Cotton (Gossypium hirsutum L.)

Introduction

Cotton is an immensely important crop for the sustainable economy of India and livelihood of the Indian cotton farming community. Cotton is generating employment for millions of farmers and others engaged in activities relating to cotton, cotton processing, transportation etc. India occupies first place in the world in terms of acreage under cotton cultivation. The cotton genus Gossypium of the Malvaceae family occurs naturally throughout the tropics and subtropics and consists of about 50 species that form a monophyletic group. Out of the 50 species, only four species are cultivated and the remaining 46 are wild species (Lee et al., 1984) [1] . Analysis of variability among the traits and the association of a particular character with other traits contributing to yield of a crop would be of a great importance in planning a successful breeding programme (Mary and Gopalan, 2006) [2] . Variability present in the population is the prerequisite in response to selection for any crop improvement programme. Selection of superior varieties or populations will be possible only when adequate variability exists in the gene pool. Hence, the insight into the magnitude of variability present in a gene pool of a crop species is of utmost importance to plant breeding programme. It is essential for the plant breeders to measure the variability with the help of parameters like phenotypic coefficient of variation, genotypic coefficient of variation, heritability and genetic advance. The coefficient of variation expressed in phenotypic and genotypic levels are used to compare the variability observed among different characters. Hence, knowledge about the variability using parameters like genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) is of paramount importance for an effective breeding programme in crops like cotton. The heritability estimates aid in determining the relative amount of heritable portion in variation and thus helps the plant breeder in selecting the elite genotypes from a diverse population. Therefore, the present study was undertaken for assessing the extent of genetic variability, heritability and genetic advance in cotton genotypes.

Materials and Methods

the experimental material for present investigation was comprised of 42 genotypes (40 genotypes and two standard checks) of cotton (Gossipium hirsutum L.) procured from Regional Research Station, AAU, Anand. The 42 genotypes and two checks were evaluated in Randomized Complete Block Design (RCBD) with three replications. Each genotype is planted in 2 rows with a spacing of 120 × 45 cm between rows and plants respectively. The experiment was conducted during kharif 2023, at three different locations of Gujarat, under the jurisdiction of Anand Agricultural University (AAU). Three locations were Anand kharif 2023 (: Regional Research Station, AAU, Anand), Jabugam kharif 2023 (: Agricultural Research Station, AAU, Jabugam) and Thasara kharif 2023 (: Agriculture Research Station for Irrigated Crops, AAU, Thasara). Five plants were randomly selected from each experiment unit and those were used for recording the observation for the seed cotton yield, its components and matriculate traits; whereas, the traits days to 50% flowering and days to 50% boll bursting were taken on plot basis. Fibre quality traits such as span length, fibre strength, fibre fineness and uniformity index values were considered for the analysis. Experimental materials used for present study are enlisted in Table 1. ANOVA Analysis of variance suggested by Snedecor (1937) [3] and reviewed by Panse and Sukhatme (1978) [4] was followed to test the significance of difference among the genotypes for all the traits under study. GCV and PCV were categorized as low, moderate and high by following classification given by Shivasubramanian and Menon (1973), where values of 0-10% indicates low variation, 10-20% represents moderate variation and values greater than 20% reflects high variation. Broad-sense heritability was calculated as the percentage ratio of genotypic variance to phenotypic variance. Heritability percentage was categorized as demonstrated by Robinson et al. [5] heritability was grouped into three categories as low (0-30%), moderate (30-60%) and high (>60%). Similarly, genetic advance was classified into three categories referred as low (0-10%), moderate (10-20%) and high (>20%).

Results and Discussion

Variability analysis

The analysis of variance for 17 traits in individual environment is presented in Table 2. The results revealed that the mean squares due to genotypes were significant for all the traits in individual environment which suggested the presence of a sufficient amount of variability in the genotypes evaluated for seed cotton yield and its component traits. The wide range of diversity allows plant breeders to select superior and desired genotypes for further crop improvement. Genotypic ( ) and phenotypic variance ( ) estimates for each trait were obtained from the analysis of variance. Additional genetic parameters, including the genotypic coefficient of variation (GCV %) and phenotypic coefficient of variation (PCV %), heritability ( ) and genetic advance as per cent of mean (GA % mean) were computed from variance components and mean values (Table 3). Estimates of GCV (32.35%, 32.64% and 31.97%) and PCV (33.45%, 34.02% and 33.44%) were high in , and , indicating a substantial amount of variability within the investigated population for this trait. The close estimates of GCV and PCV values suggested that genetic constitution of trait play important role in the expression of trait in the environment. High GCV and PCV for monopodia per plant were also reported by Nikhil et al. (2018) [6] , Premlatha et al. (2020) [7] and Patel et al. (2023) [8] . Moderate GCV and PCV were recorded for several traits, including plant height, GCV (13. [6] , Premlatha et al. (2020) [7] and Patel et al. (2023) [8] . In contrast, for days to 50 % flowering low GCV ( [9] and Premlatha et al. (2020) [7] . [7] and Vijay et al. (2025) [10] . [7] , Meena et al. (2022) [11] and Patel et al. (2023a) [8] . [6] , Premlatha et al. (2020) [7] and Vijay et al. (2025) [10] . High heritability combined with low genetic advance as a percentage of the mean was noticed for days to 50 % flowering (

Heritability

References

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