Genetic studies in Cherry Tomato (Solanum lycopersicum var. cerasiforme Mill.)

Genetic studies in Cherry Tomato (Solanum lycopersicum var. cerasiforme Mill.)

Usma Jan¹ , Baseerat Afroza¹ , Zahoor Dar² , Azra Lateef¹ , Mir Tabasum Ashraf¹ , Amreena Sultan¹ , Afiya Khurshid¹ , Syeda Farwah¹

¹Division of Vegetable Science, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar, Srinagar, Jammu and Kashmir (190 025), India

²Division of Plant Breeding and Genetics, Dryland Agriculture Research Station, Budgam, Sher-e Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar, Srinagar, Jammu and Kashmir (190 025), India

Corresponding Author Email: usmabhat9@gmail.com

DOI : http://dx.doi.org/10.53709/CHE.2022.v03i01.003

Abstract

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Introduction

Cherry tomato (Solanum lycopersicum var. cerasiforme Mill., 2n=2x=24.) regarded as botanical variety of cultivated tomato has become more popular all over the world because of its good taste with low calories and fruit set even at high temperatures [12]. The popularity and demand for cherry tomatoes are increasing due to their nutritional and medicinal properties. However, the area under cherry tomato is currently negligible in the country primarily due to the lack of suitable cultivation techniques, the requirement of highly intensive management and improved production technology. In India, cherry tomatoes are mostly grown in Hyderabad, Gujarat, Andhra Pradesh, Rajasthan, Karnataka, Bihar, etc.

Identification and development of new cultivars are important to improve production and productivity. Planning and execution of a breeding program for the improvement of quantitative attributes depend to a greater extent upon the magnitude of genetic variability and the extent to which desirable characters are heritable [1]. Genetic parameters like the genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability and genetic advance are useful biometrical tools for the determination of genetic variability. Heritable variation can be effectively studied in conjugation with genetic advance. High heritability alone is not enough to make efficient selection in segregating generation and needs to be accompanied by a substantial amount of genetic advance [3]. The characters showing high heritability along with high estimates of genetic advance are more effective for selection.

A correlation study provides a measure of association between characters and helps to identify important characters to be considered while making selection. Knowledge of the correlation between yield and other characteristics is helpful in selecting suitable plant types. The correlation coefficient would indicate how much progress might be expected from selecting two variables simultaneously. If significant correlation values are found between yield and other economic traits, a considerable improvement could be made through selection. In the agro-ecological perspective of Kashmir, information regarding variability on cherry tomatoes needs to be studied for a successful breeding programme to breed new varieties. Therefore, fifteen cherry tomato genotypes were evaluated for genetic variability, heritability, genetic advance and correlation among the characters to breed new varieties in Kashmir.

Material and Methods

The study was conducted  for eight months during kharif 2019 at the experimental field, (34°.1´ North latitude and 74°.89´ East longitude with an altitude of 1685 meters above mean sea level) Division of Vegetable Science SKUAST-Kashmir to generate information regarding variability, heritability and correlation among various traits in cherry tomato genotypes. The experimental material comprised of fifteen diverse genotypes of cherry tomato. The experiment was conducted in Randomized Block Design with three replications. The observations were recorded on various maturity, yield and yield attributing and quality traits. Analysis was done as per standard statistical procedures.

Results and Discussion

Analysis of variance revealed highly significant differences among genotypes for all the traits under study, indicating a sufficient amount of variability in the genotypes. This provides an ample opportunity for selecting suitable genotypes with desirable means for the traits of interest. These results are following those of [8], [9].

A wide range of variability was observed for most of the traits under study as depicted by range values. The range reflects the amount of phenotypic variability, which unreliable as it includes phenotypic, genotypic and GxE interaction components and does not reveal why the character is showing a high degree of variability. The high genotypic variance was shown by a number of fruits plant^-1, plant height, a number of seeds fruit^-1 and the harvest duration, indicating a genetic component’s contribution for total variation. The magnitudes of genotypic coefficients of variation were slightly lower than corresponding phenotypic coefficients of variation, which indicates the role of the environment in the expression of these traits. High genotypic coefficients of variation were shown by all the traits except days to first flowering, days to first fruit harvest and harvest duration, indicating the higher magnitude of variability for these traits that can be utilized in future breeding programmes.

The heritability in a broad sense was high above 60 per cent for all traits except pericarp thickness, suggesting that the selection based on phenotype would be more effective, and there is every possibility to transmit these traits into offsprings. The genetic advance was found to be low in almost all traits except the number of fruits plant^-1 (88.04%), plant height (81.60%), number of seed fruit^-1 (42.62%) and harvest duration (24.37%). In the present study, traits showing high heritability along with high genetic advance were identified as plant height, the number of fruits plant^-1, harvest duration and the number of seeds fruit^-1. High heritability and high genetic advance are more reliable than low heritability and low genetic advance as it indicates additive gene effect, which responds better to the selection. Similar results on variability, coefficients of variance, heritability and genetic advance have also been reported by [12], [5], [8], [11], [14], [15], [2] and [6].

The estimates of genotypic correlation coefficients were generally higher than corresponding phenotypic correlation coefficients but similar in direction. The maturity traits viz. days to flowering, days to first fruit harvest were positively and significantly correlated with each other but negatively and significantly correlated with the number of flower clusters plant^-1, the number of fruits plant^-1, harvest duration, average seed yield plant^-1, average fruit yield plant^-1 and average fruit yield plot^-1. Days to first fruit harvest were also negatively and significantly correlated with average fruit weight. The most economic traits viz. fruit yield plant^-1 and average fruit yield plot^-1 were found to be positively and significantly correlated with plant height, number of flower clusters plant^-1, number of fruits cluster^-1, number of fruits plant^-1, average fruit length, average fruit width, average fruit weight, pericarp thickness, harvest duration, number of seeds fruit^-1, average seed weight fruit^-1 and average seed yield plant^-1 thereby indicating that the selection for these traits would automatically bring about improvement in yield. Several research workers viz. [10], [7], [13], [4] etc. have reported significant correlations between different traits in cherry tomato.

The estimates of different genetic parameters and the association of different characters are important for a better understanding the nature and magnitude of genetic variability present in the breeding material. The knowledge of the degree of correlation of yield or any other character of interest with its component traits is necessary for indirect selection of yield by giving appropriate emphasis for each of these characters.

Conclusion

For most of the traits under study, wide range of variability was observed which could be essential for desired genetic improvement. Genotypic coefficients of variation were higher than the corresponding environmental coefficients of variation suggesting that the selection for these traits would be quite effective for improvement. High heritability coupled with high genetic advance as per cent of mean specify the significance of these traits for choosing superior genotypes. The knowledge of the degree of correlation of yield or any other trait of interest with its component traits is important in selecting indices to enable effective direct selection.

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