Assessment of genetic variability, heritability and correlation studies in tomato (Lycopersicon esculentum Mill.)

Introduction

Tomato (Lycopersicon esculentum Mill.), belonging to the family Solanaceae (2n = 24), is one of the most important vegetable crops cultivated worldwide and is popularly known as the "poor man's orange" in India (Rick, 1976; Barton, 1950) [1,2] . It is a rich source of vitamins (A, C), minerals, lycopene and antioxidants and occupies a prominent place among vegetables after potato and sweet potato. India ranks second in tomato production after China (FAOSTAT, 2020) [3] . In Uttar Pradesh, the area under tomato was approximately 0.20 lakh hectares with a production of 5.29 million tonnes during 2019-20 (NHB, 2020-21). For a breeder, the presence of adequate genetic variability is the basic requirement for effective selection. Phenotypic variation is composed of genetic and environmental components, and only the heritable fraction can be exploited consistently through selection. Consequently, estimates of genotypic and phenotypic coefficients of variation, heritability and genetic advance are useful for understanding the probable response to selection (Johnson et al., 1955; Falconer, 1989) [8,5] . The usefulness of variability estimates in plant breeding has also been emphasized by Hutchinson (1940) [6] .

Genetic variability is the basic requirement for any successful breeding programme. Estimation of genotypic and phenotypic coefficients of variation, heritability and genetic advance helps in understanding the nature of gene action and devising appropriate selection strategies (Burton, 1952; Johnson et al., 1955; Lush, 1949) [7,8,14] . Correlation and path coefficient analyses further elucidate the interrelationships among yield and its component traits (Al-Jibouri et al., 1958; Dewey and Lu, 1959) [9,10] . Fruit yield is a complex trait and its improvement requires understanding the relationships among yield and its component traits. Correlation analysis identifies the direction and magnitude of association, whereas path coefficient analysis partitions correlations into direct and indirect effects, thereby helping to identify characters that can be used as selection criteria (Searle, 1961; Kumar et al., 2013) [11,12] . Genetic divergence analysis is useful for identifying contrasting parents and planning crosses, particularly when a breeding programme aims to combine high yield with earliness and desirable quality traits. (Frankel. 1998) [13] This study evaluates genetic variability, heritability, and genetic advance in tomatoes (Lycopersicon esculentum Mill.) to establish reliable selection criteria for yield and yield attributing traits. By utilizing correlation coefficient and path coefficient analysis to identify positive and negative relationships effecting yield and measuring genetic divergence among genotypes, to exploit the available variability present in the genetic material in the form of some specific group or classes, the divergences studies based upon some desirable parameter is very essential. Therefore, this experiment was conducted to observe growth, yield and quality attributes of cowpea on different levels of genetic variability, to identify the best genotypes with high yield, early maturing suited conditions of Prayagraj, Uttar Pradesh.

Materials and Methods

The experiment entitled "Genetic Variability, Heritability, and Correlation Studies in Tomato (Lycopersicon esculentum Mill.)" Under Prayagraj agro-climatic conditions, was done on genetic variability, heritability, correlation in tomato during September 2025-January 2026 at the Horticulture Research Field, Department of Horticulture, Sam Higginbottom University of Agriculture, Technology and Sciences. The analysis was laid out in randomized block design with three replications. The planting was done with a spacing of 60 cm, row to row and 45 cm, plant to plant respectively, each plot with 9 plants. Experimental materials comprised of 20 genotypes viz., TMTH 2246, TO 1057, TMTH 218, TMTH 291, Abhilash, TMTH 216, US 2853, Kashi Amul, Kashi Amrit, Kashi Chayan, Kashi Aman, Kashi Anmol, Kashi Aadarsh, Kashi Anupam, Kashi Lalima, Kashi Abhiman, Kashi Sharad, Kashi Hemant, Kashi Vishesh and Kashi Adbhut (Check) were used.

Results and Discussion

Analysis of variance

The analysis of variance (Table 1) revealed highly significant differences among the 20 genotypes for all 20 quantitative characters studied. This indicated the presence of substantial genetic variability in the experimental material, offering ample scope for selection and genetic improvement of tomato. Similar findings of significant genotypic differences for yield and yield-attributing traits in tomato have been reported by earlier workers (Ahirwar and Prashad, 2013; Dar and Sharma, 2011; Kerketta and Bahadur, 2019; Kumar et al., 2013) [15,16,17,12] .

Genetic Parameters

Estimates of genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability (broad sense), genetic advance (GA) and genetic advance as percent of mean (GAM) are presented in Table 2. Moderate Genotypic coefficient of variation (GCV) was recorded for Number of branches and number of clusters per plant (19.74%), Fruit yield t/ha (12.96%), Fruit yield per plot (12.69%), Fruit yield per plant (12.53%), Days taken for first fruit harvest (11.85%), Days to first flowering (11.69%), Number of days to marketable maturity (10.84%), Test weight (10.39%). Low GCV was recorded for pericarp thickness (9.81%), plant height (7.43%), Average number of fruits per plant (7.18%), Days to 50% flowering (7.16%), Average fruit weight (7.15%), Vitamin C content (7.08%), Days to first fruiting (7.00%), Total Soluble Solids (5.21%), Days to 50% fruits setting (3.70%), Fruit size-Polar (3.55%), and Fruit size-Equatorial (2.92%) with least value. Whereas Moderate Phenotypic coefficient of variation (PCV) was recorded for Fruit yield t/ha (13.55%), Fruit yield per plot (13.43%), Fruit yield per plant (

Correlation coefficient analysis

Genotypic Correlation coefficient (Table 3) analysis revealed that Fruit yield per hectare exhibited highly significant and positive correlation with Plant height, Number of branches, Number of clusters per plant, Average number of fruits per plant, Fruit size-Polar (cm), Fruit size-Equatorial (cm), Average fruit weight (g), Fruit yield per plant (kg), Fruit yield per plot (kg), Test weights, Vitamin C content (mg/100g), and Pericarp thickness. Fruit yield per hectare showed significant negative correlation with Days to first flowering, Days to first fruiting, Days to 50% flowering, Days to 50% fruits setting, Number of days to marketable maturity, Days taken for first fruit harvest, and TSS ( 0 Brix). 4) analysis revealed that Fruit yield per hectare exhibited highly significant and positive correlation with Plant height, Number of branches, Number of clusters per plant, Average number of fruits per plant, Fruit size-Polar (cm), Fruit size-Equatorial (cm), Average fruit weight (g), Fruit yield per plant (kg), Fruit yield per plot (kg), Test weights, Vitamin C content (mg/100g), and Pericarp thickness. Fruit yield per hectare showed significant negative correlation with Days to first flowering, Days to first fruiting, Days to 50% flowering, Days to 50% fruits setting, Number of days to marketable maturity, Days taken for first fruit harvest, and TSS( 0 Brix).

Phenotypic Correlation coefficient (Table

Conclusion

From the present study it was concluded that out of 20 genotypes of Tomato, genotypes namely, Kashi Aman exhibited substantially higher yield and performed better for yield and its attributing traits. Moderate estimate of GCV along with high heritability coupled with high genetic advance as percent of mean was recorded for days to first flowering, number of days to marketable maturity, number of branches, number of clusters per plant, days taken for first fruit harvest, test weights, fruit yield per plant (kg), fruit yield per plot (kg), Fruit yield (t/ha). Genotypic correlation was higher than the phenotypic ones. Genotypic Correlation coefficient analysis revealed that Fruit yield per hectare exhibited highly significant and positive correlation with Plant height, Number of branches, Number of clusters per plant, Average number of fruits per plant, Fruit size-Polar (cm), Fruit size-Equatorial (cm), Average fruit weight (g), Fruit yield per plant (kg), Fruit yield per plot (kg), Test weights, Vitamin C content (mg/100 g), and Pericarp thickness.

References

1. Rick CM. Evolution of tomato. In: Evolution of Crop Plants. New York: Longman Publications; 1976. p. 268-273.
2. Barton DW. Pachytene morphology of tomato chromosome complement. Am J Bot. 1950;37(8):639643.
3. National Horticulture Board. Ministry of Agriculture and Farmers Welfare, Government of India. 2020-2021.
4. Falconer DS. Introduction to Quantitative Genetics. 3rd ed. New York: Longman; 1989. 386 p.
5. Hutchinson JB. The application of genetics to plant breeding. J Genet. 1940; 40:271-282.
6. Burton GW. Quantitative inheritance in grasses. Proc 6th Int Grassland Congress. 1952; 1:227-283.
7. Johnson HW, Robinson HF, Comstock RE. Estimates of genetic and environmental variability in soybean. Agron J. 1955; 47:314-318.
8. Al-Jibouri HA, Miller HA, Robinson HF. Genotypic and environmental variances and covariances in upland cotton crosses of interspecific origin. Agron J. 1958; 50:633-636.
9. Dewey DR, Lu KH. A correlation and path coefficient analysis of components of crested wheatgrass seed production. Agron J. 1959; 51:515-518.
10. Searle SR. Phenotypic, genotypic and environmental correlations. Biometrics. 1961; 17:474-480.
11. Kumar D, Kumar R, Kumar S, Bhardwaj ML, Thakur MC, Kumar R, et al. Genetic variability, correlation and path coefficient analysis in tomato. Int J Veg Sci. 2013; 19:313-323.
12. Frankel OH, Brown AHD, Burdon JJ. The Conservation of Plant Biodiversity. 2nd ed. Cambridge: Cambridge University Press; 1998. p. 56-78.
13. Lush JL. Heritability of quantitative characters in farm animals. Proc 8th Int Congress Genetics. Hereditas Suppl. 1949;3(2):356-375.
14. Ahirwar CS, Prashad VM. Variability pattern in agromorphological characters in tomato genotypes (Lycopersicon esculentum Mill.). Trends Biosci. 2013;6(6):758-761.
15. Dar RA, Sharma JP. Genetic variability studies of yield and quality traits in tomato (Solanum lycopersicum L.). Int J Plant Breed Genet. 2011;5(2):168-174.
16. Kerketta A, Bahadur V. Genetic variability, heritability and genetic advance for yield and yield contributing characters in tomato (Solanum lycopersicum L.) genotypes. Int J Pure Appl Biosci. 2019;7(3):577-582.