Evaluation and Estimation of Genetic Divergence of Tomato Hybrids by Using Principle Component Analysis and Cluster Analysis Under High Temperature

Abstract

Increasing temperature is a major limiting factor for crop productivity. However, Tomato (Solanum lycopersicum L.) is highly sensitive to increasing temperature as a result major yield loses. Thus understanding the mechanism of high temperature become crucial for tomato improvement programme because it depends on the genetic variation which are present in the genome of tomato. Therefore, an experiment was conducted at the field of Department of Plant Breeding and Genetics using a randomized complete block design with two treatments and each treatment has three replications to determine the high temperature tolerant genotype on the base of phenological, physiological and morphological parameters. The genetic material proposed the considerable amount of diversity for all the studied parameters. Results shows that cumulative variation of first six principal components is 83.671 % and their eigen value greater than 1under normal treatment, while cumulative variation of first four principal components under high temperature stress is 86.690% having eigen value greater than 1. Under normal temperature PC1 contributed maximum variation 0.873% for Number of days to first fruit set, PC3 and PC4 contribute minimum variation -0.059 and -0.094% for fruit diameter and pericarp thickness respectively. While under high temperature PC1 contribute the maximum variation 0.968 and 0.969% for Flesh thickness and Shelf life respectively, and PC2 contribute minimum variation -0.057 and -0.075 for fruit length and fruit diameter respectively. According to the score plot under normal treatments genotypes Tom-15 and Cchaus were close to each other and quit away from all other genotype while under high temperature Anna quit away from other genotypes and show the maximum variation. Biplot graph show that individual fruit weight, fruit length and number of days to 50% flowering have the large variability and stem diameter and plant height have the lowest variability under normal treatments and under high temperature stress number of days to first flowering, number of flowers/cluster and number of days to 50% flowering have the maximum variability, while fruit length, fruit diameter, flesh thickness, pericarp thickness, shelf life and yield per plant had showed minimal variation. All the hybrids were grouped into 3 clusters. Maximum number of genotypes was quartered in cluster I and II under stressed and normal treatment respectively. Maximum distance to centroid in cluster I (55.669) and minimum distance to centroid in cluster III (00) under stressed treatment while under normal treatments maximum distance to centroid in Cluster II (302.087) and minimum distance to centroid in cluster I (68.957). Therefor it is suggested that cluster I has the maximum divergence or variation which is suitable for future breeding programme for the development of temperature tolerant genotypes.