NATURE OF GENE ACTION FOR SOME ECONOMIC CHARACTERS OF TOMATO (Lycopersicon esculentum L.) VARIETIES

Abstract

Knowledge about the mode of gene action of economical traits (which directly contribute towards yield and fruit quality) in any crop like tomato (lycopersicon esculentum L.) helps to formulate the genetic basis for breeding. Thus, the aim of the present study was to estimate different types of gene action affecting some characteristics of tomato. For this purpose, five tomato varieties were used. These varieties were: Advantage 2 (P 1 ), Cherry (P 2 ), Fatma (P 3 ), Edkaway (P 4 ) and Castle Rock (P 5 ). The varieties were crossed by using complete diallel crosses mating design, in order to produce 20 hybrids. All genotypes were evaluated during two seasons for some vegetative traits, fruit characteristics and physiological traits. The data were subjected to biometrical analysis and the obtained results revealed that the mean squares of entries were highly significant for the studied traits, leading to the further partitioning of genetic variance into its components. The combined data over the two seasons showed that additive genetic variances were higher than their corresponding values of dominance genetic variances for plant height and number of primary branches per plant. On the other hand, values of dominance genetic variances were higher than their corresponding values of additive genetic variances for leaf area, fruit characters and chemical traits. Furthermore, heritability in broad sense (h 2 b%) was 93.15% for plant height, 85.32% for number of primary branches per plant, 78.68% for leaf area, -92.38% for locules number per fruit, 97.02% for firmness fruit, 68.78% for Pericarp thickness, 71.62% for total soluble solids, 81.58% for ascorbic acid content and 87.13% for lycopene content. However, heritability estimates in narrow sense (h 2 n%) were more less than the corresponding values in all studied traits, indicating that the role of non-additive genetic variance in the genetic expression of these traits are non-negligible. These genetic parameters could be used in carrying out breeding programs suitable for Tomato.