Estimation of Genetic Components and Heritability for Fruits Yield and Quality Characters in Tomato (Solanum Lycopersicom)

Abstract

Six parental genotypes of tomato (Solanum Lycopersicom), i.e. Castel ruck (p1), Imperial (p2), Crystal (p3), Perso (p4), Pascal (p5) and Valcum valentime (p6) were crossed in a half diallel fashion to produce F1 in order to study some genetic components and ratios for some economic traits. The study consisted of twenty one genotypes; these genotypes were six inbred lines (parents) and fifteen F1 crosses. These twenty one genotypes were subjected to evaluation trial at Moshtohor village, Kalyobiya Governorate, Egypt during summer seasons of 2016 in a randomized complete block design with three replications. Data on yield and its components and fruit traits were recorded and subjected to statistical analysis to investigate Hayman's approach were used to study genetic components and heritability which control these traits. Data indicated that the additive component (D) was insignificant for average fruit weight, number of fruits and total yield per plant traits indicating the importance of non-additive effect in the inheritance of these traits. Meanwhile, the dominance genetic variations H1 and H2 were significant or highly significant for all studied fruits traits, showing the importance of dominance genetic effects in the inheritance of these traits. The average degree of dominance (H1/D) ½ showed over dominance for the average fruit weight, number of fruits and fruit yield per plant traits. The proportion of gene with positive and negative effects (H2/4H1) in the parents was lower than one quarter proportion, indicating unequal distribution between the positive and negative alleles among the parents. The ratio of dominant to recessive alleles (KD/KR) in the parents was more than (one), indicating that the six parents used in the present study carried more dominant than recessive allels. Heritability estimates in broad sense are very high for average fruit weight trait (100%), number of fruits (96%) and fruit yield per plant (92%), indicating the importance of genetic components of variation in the inheritance of these traits encouraging the usage of breeding programs to improve these traits. Meanwhile heritability estimates in narrow sense was low (2.7%, 1.4% and 0.7 %, respectively) clarifying the importance of non-additive genetic effects in the inheritance of these traits. These results indicate that a major of total phenotypic variances due to dominance and/or over-dominance and the environmental factor affects the inheritance of these traits. So it is of great importance to develop new hybrids in order to obtain maximum fruits number.