GENETIC DIVERGENCE AND CAUSE EFFECT RELATIONSHIP STUDIES IN TOMATO “(Solanum lycopersicum L.)’’ FOR YIELD AND YIELD ATTRIBUTING TRAITS UNDER LOW TEMPERATURE
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Date
2021
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DRPCAU, PUSA
Abstract
The current research was conducted at the “Vegetable Research farm of Dr. Rajendra Prasad Central Agricultural University, Pusa, Bihar”, during the rabi season (2020-21) having Twenty-five tomato genotypes, including a control, Kashi Vishesh to evaluate the twenty-five genotypes of tomato (Solanum lycopersicum L.) in a Randomized Block Design with three replications for yield and yield attributing traits. Studies were carried out on “variability, character association, path analysis, and genetic divergence” for characters like “Plant height (cm), number of primary branches/plants, number of days to first flower initiation, number of flowers/clusters, number of fruits/clusters, number of clusters/plants, number of days to first picking, polar diameter of fruit (cm), equatorial diameter of fruit (cm), average fruit weight (g), TSS content of the fruit (obrix), acidity of the fruit (%), number of fruits/plant and fruit yield/plant (kg)”.
Analysis of variance (ANOVA) revealed highly significant differences among the genotypes for every trait. Estimations of genetic coefficient of variation (GCV) and
phenotypic coefficient of variation (PCV) were high for the characters like: “fruit yield per plant (kg), average fruit weight (g), equatorial diameter of fruit (cm), number of primary branches/plants, plant height (cm), polar diameter of fruit (cm), number of fruits/plant and acidity of the fruit (%)”. A high heritability value was detected, as well as a high genetic advance as percent of the mean for all the fourteen characters. These characters indicated that the presence of additive gene effects that may be exploited through phenotypic selection to improve yield.
Based on correlation and path analysis, “Plant height, Average fruit weight and number of fruits per plant” exhibited positive and significant correlation with yield per plant having their positive direct effect suggesting that during selection these traits may be considered as prime traits to improve the yield of tomato.
The twenty-five genotypes were divided into nine clusters using Tocher’s method, however, the genotype distribution within each cluster varied in number. Cluster I had the highest number of genotypes (eleven) followed by (four) genotypes in cluster III, (three) in cluster VI, (two) in cluster V and cluster II, IV, VII, VIII, and IX had only (one) genotype each. Cluster I and Cluster V had the highest and lowest intra-cluster distances, respectively. The inter-cluster distance was lowest between clusters II and V and highest between clusters VIII and IX, indicating these genotypes might be used in an inter-varietal hybridization program to achieve superior recombinants. Average fruit weight (24.00 %) contributed the most to divergence, followed by acidity of the fruit (16.33 %), TSS content of the fruit (15.67 %), and number of primary branches per plant (15.00 %). They have collectively contributed 71 %. So, based on this study, genotypes EC 320574 (Cluster V) and PDT-3-1 (Cluster VIII) were selected as superior lines based on high inter-cluster distance alongside mean performance for most of the yield attributing traits suggesting that these genotypes may be used in crossing programme to obtain heterotic recombinants as well as transgressive segregants.