1 Introduction

Tomato (Solanum lycopersicon L.) is one of the most important vegetable crops grown throughout the world because of its wider adaptability, high yielding potential and suitability for variety of uses in fresh as well as processed food industries. The red pigment in tomato (lycopene) is now being considered as the “world’s most powerful natural antioxidant” (Jones, 1999) Therefore, tomato is one of the most important protective foods because of its special nutritive value. However, the average national productivity is very low (19.5 tonnes/ha as compared to other countries like USA (81 t/ha), Spain (74 t/ha) and Brazil (60.7 t/ha) (NHB, 2014). This indicates that there is a need to increase the productivity of this crop by developing high yielding varieties through appropriate breeding work to meet the demand of domestic and export markets. The development of an effective plant breeding programme is depending upon the assessment of polygenic variation, selection of elite genotypes, choice of parents and breeding procedures. Crop improvement depends upon the magnitude of genetic variability and the extent to which desirable characters are heritable. Genetic variability for yield and yield components is essential in the base population for successful crop improvement (Allard, 1960). Yield and yield components are quantitative characters and are poly genetically inherited which are greatly influenced by environment. The phenotype of a character is the resultant of interaction between genotype and environment. Genetic parameters such as Genotypic, Phenotypic coefficient of variation (PCV and GCV) are useful in detecting the amount of variability present in the available genotypes.

Heritability and genetic advance help in determining the influence of environment in expression of the characters and the extent to which improvement is possible after selection (Robinson et al., 1949). Heritable variation can be effectively studied in conjunction with genetic advance. High heritability alone is not enough to make efficient selection in segregation, unless the information is accompanied for substantial amount of genetic advance (Johnson et al., 1955). Tomato, being self pollinated crop in general, we can create genetic variability through hybridization which could be favorably utilized in developing a genotype with all desirable characters. The results obtained on Variability, Heritability and Genetic Advance as per cent of Mean (GAM) are discussed here.

2 Material and Methods

The present investigation on “Studies on genetic variability, heritability and genetic advance for yield and quality traits in Tomato (Solanum lycopersicum L.)” was carried out during the years 2014-15 at College of Horticulture, University of Horticultural Sciences Campus, GKVK, Bengaluru. The experimental site is situated at 13⁰ North latitude and 77.37⁰ East longitudes Eastern Dry Zone of Karnataka (Zone-5). The experimental material consisted of 300 F₆ recombinant inbred lines were developed by using parents Vaibhav and Anaga cross. The experiment was laid out in Randomized Block Design with three replications. Each entry was grown in two rows with 10 plants in each row by adopting inter row spacing of 60cm and intra row spacing of 45 cm. All recommended agronomic package of practices were followed to grow a healthy crop. The observations were recorded on various growth, yield and quality parameters. The analysis of variance for testing the variance among treatments was carried out as per the method suggested by (Panse and Sukhatme, 1967). The genotypic and phenotypic coefficients of variation were calculated according to the formula given by (Falconer, 1982). Categorization of the range of variation was proposed by (Sivasubramanian and Madhavamenon, 1973). Heritability (h2) in the broad sense was calculated according to the following formula given by (Burton, 1952). The range of heritability and genetic advance as per cent of Mean (GAM) were classified as suggested by (Johnson et al., 1955).

3 Result and Discussion

3.1 Variability

The analysis of variance (Table 1) revealed that highly significant differences among the genotypes for all the characters indicating sufficient variability existed in the present material selected for the study and indicating the scope for selection of suitable initial breeding material for crop improvement. However, the absolute variability in different characters does not permit identification of the characters showing the highest degree of variability. Therefore, PCV and GCV values were estimated. The coefficient of variation whether it is genotypic or phenotypic, both are useful in studying the extent of variability in different characters as it measures the range of variability. The PCV values were slightly higher than the respective GCV for all the characters denoting little influence of environmental factors on their expression. The PCV and GCV values were high particularly for, fruit yield per plant due to high variability available in the traits (Table 2). Moderate estimates of PCV and GCV are obtained for plant height, average fruit weight, pericarp thinkness, number of locules/fruit, total soluble solids, number of fruits per plant and number of branches per plant (Singh, 2009 and Kumar and Thakur, 2007) indicated a good deal of variability in those characters signifying the effectiveness of selection of desirable types for improvement. Whereas, moderate PCV and low GCV was recorded for the character pH. Low PCV and GCV values for days to first flowering (Mohan et al., 1996) suggesting less variability existed in the character.

Table 1 Analysis of variance (ANOVA) for recombinant inbred line populations of Vaibhav x Anaga cross

Table 2 Magnitude of genetic variability parameters of recombinant inbred line populations of Vaibhav x Anaga cross

This variability indicates that good amount of variability present in the recombinant inbred line population which could be improved through selection to increase the gene flow and to fix favorable alleles.

3.2 Heritability and Genetic advance

Perusal of results on heritability and genetic advance as per cent of mean (GAM) revealed that heritability estimates were high for all the characters studied. This suggested the greater effectiveness of selection due to less influence of environment and improvement to be expected for these characters in future breeding programme. Johnson et al. (1955) suggested that high heritability coupled with high genetic advance as percentage of mean (GAM) were more useful than heritability alone in predicting the resultant effect during selection of best individual genotype. Genetic advance is the measure of genetic gain under selection and expression in percentage of mean. In the present experiment high heritability and genetic advance as per cent of mean (GAM) was recorded for plant height, number of branches per plant, average fruit weight, number of locules per fruit, pericarp thickness, number of fruits per plant, fruit yield per plant and total soluble solids. The results are supported by findings of (Singh, 2009; Ara, 2009; Patil, 1996: Golani et al., 2007 and Sharma et al., 2006) indicating predominance of additive gene action for these characters. Simple selection based on phenotypic performance of these characters would be more effective.

References

Allard W., 1960, Principles of Plant Breeding (John Willey and Sons. Inc. London), pp. 83-108

Ara A., Raj N., Nazzer A., and Khan S.H., 2009, Genetic variability and selection parameters for yield and quality attributes in Tomato, Indian Journal of Horticulture, 66(1): 73-78

Burton G.W., 1952, Quantitative inheritance in grasses, Proceedings of 6th International Grasslands Congress, 1: 277-283

Falconer D.S., 1982, Introduction to quantitative genetics (Oliver and Boyd, London), pp.340

Golani I.J, Mehta D.R., Purohit V.L., Pandya H.M., and Kanzariya M.V., 2007, Genetic variability, correlation and path coefficient studies in tomato. Indian J. of Agric. Rese, 41(2): 146-149

Johnson H.W., Robinson H.F., and Comstock R.E., 1955, Estimates of genetic and environmental variability in soybean, Agronomy Journal, 47(7): 314-318

http://dx.doi.org/10.2134/agronj1955.00021962004700070009x

Jones J.B., 1999, The field, green house and house garden, Tomato plant culture (CRC Press, LLC, Boca Raton, Florida), pp.199

Kumar R., and Thakur M.C., 2007, Genetic variability, heritability, genetic advance, correlation coefficients and path analysis in tomato, Haryana Journal of Horticultural Science, 34(3&4): 370-373

NHB, 2014, Indian Horticulture Database, http://nhb.gov.in/area-pro/database-2014.pdf

Panse V.G., and Sukhatme P.V., 1967, Statistical Methods for Agricultural Workers, ICAR, New Delhi

Patil M.G., 1996, Investigations on genetic improvement and production practices in processing tomatoes (Lycopersicon esculentum Mill.), PhD. Thesis, University of Agricultural Sciences, Dharwad

Robinson H.F, Comstock R.E and Harvey P.H., 1949, Estimates of heritability and degree of dominance in corn, Agronomy Journal, pp.253-259

Sharma J.P., Kumar S., Singh A.K., and Bhushan A., 2006, Variability and inter relationship studies in tomato (Lycopersicon esculentum Mill.), Journal of Research, SKUVAST-J, 5(1): 100-104

Singh A.K., 2009, Genetic variability, heritability and genetic advance studies in tomato under cold drip region of Ladakh, Indian Journal of Horticulture, 66(3): 400-403

Sivasubramanian S., and Madhavamenon P., 1973, Combining ability in rice, Madras Agricultural Journal, 60: 419-421