Combining Ability, Heritability and Genetic Variance in Tomato (Lycopersicon lycopersicum) Genotypes

Abstract

A study was conducted to determine gene actions controlling yield and other qualitative traits of tomato (Lycopersicon lycopersicum) as well as combining ability among selected genotypes at the Teaching and Research Farm of the Ladoke Akintola University of Technology, Ogbomoso during the 2017 and 2018 cropping seasons. Five tomato genotypes and ten offspring (F1), obtained from a 5×5 diallel crosses were sown in plots, arranged in a Randomized Complete Block Design, with three replicates. Data were collected on plant height (PH), number of cluster per plant, days to 50% flowering (50%FL), individual fruit weight (IFW), number of fruits per plant (NFPP), pericarp thickness (PT), number of lobe (NOL), number of seeds per fruit (NSPF), fruit lycopene (LYCOP), ascorbic acid content (ASCO) and fruit yield (YH). Data collected were subjected to Analysis of Variance (P=0.05). Also, diallel analysis was carried out to determine the General and Specific combining abilities (GCA and SCA) of the parents and hybrids respectively, following the Griffing (1956) Method II for partial diallel analysis. Results obtained showed significant differences among the genotypes, for all the characters measured. Also, non-additive and additive gene actions were responsible for the genetic control of the traits. The ratio of GCA and SCA were < 1 for Plant height, CPPL, 50%FL, IFW, NFPP, PT, NOL, NSPF, LYCOP, ASCO and YH thus revealing the preponderance of non-additive gene action. GCA analysis suggested that parents Uc-op and Ibadan-local were the best general combiners while, SCA performance suggested that FDT4 X FDT2 was the best specific combiner. Broad sense heritability for NOL, NSPF, LYCOP, and ASCO were above 90%, indicating that they were highly heritable while narrow sense heritability of NOL was very high (55% and 83% respectively), PH, NSPF, NFPPL and LYCOP were moderate ranging between 20% and 38%. It is concluded that high yielding tomato hybrids, best combiners and a guide line for the assessment of relative parents breeding potential of the parents could be established following diallel technique.