EVALUATION OF F 2 POPULATIONS OF TOMATO THROUGH ASSESSMENT OF HERITABILITY AND CHARACTER ASSOCIATIONS

Abstract

The present study was investigated to find degree of genetic variability, heritability, and genetic advance of the yield and its contributing attributes among F 2 populations of tomato. The research study was conducted in a randomized complete block design (RCBD) with three replications during the rabi season 2020-2021 at the Sher-e-Bangla Agricultural University, Dhaka. The F 2 populations were characterized for morphological traits e.g. days to first flowering, days to fruiting, plant height, branches per plant, cluster per plant, fruits per plant, and yield per plant. Analysis of variance regarding morphological attributes showed highly significant differences (P≤ 0.01) among tomato F 2 populations. Minimum days to first flowering and days to first fruiting were recorded for genotype P 3 (23.33 days and 40.33 days), respectively. Maximum plant height, clusters per plant, fruits per plant, and single fruit weight were observed for C12, C5, C5, and C4 with values of 118.22 cm, 9.89, 38.89, and 100.47 g. Little differences were observed between the phenotypic coefficient of variation and genotypic coefficient of variation for all traits except branches per plant and cluster per plant indicating that most of the traits were minor influenced by environmental factors for their phenotypic expression. All traits had high broad heritability (h 2 b), but only branches per plant (42.90) were found moderate heritability. Low genetic advance as a percent of mean (9.62) was recorded for days to first fruiting. Moderate genetic advance was found in fruit diameter (15.59) and plant height (19.21). Low to moderate genetic advance suggests the action of both additive and nonadditive genes and the favourable influence of environment in the expression of the mentioned traits. Yield per plant was positively and significantly associated with plant height (0.417** and 0.317*), branches per plant (0.370** and 0.276*), cluster per plant (0.519** and 0.393**), fruits per plant (0.573** and 0.507**), fruit diameter (0.355** and 0.493**) and single fruit weight (0.586** and 0.447**) at both genotypic and phenotypic level. High positive direct effects on total yield per plant were shown by plant height (6.263) followed by single fruit weight (3.611), number clusters per plant (2.610), fruit length (2.178) and fruits per plant (0.367). Plant height, single fruit weight, cluster per plant having high positive direct effects along with positive significant correlation with yield indicating that these traits can be selected for the improvement of fruit yield. Positive and highly significant heterosis was found in F 2

population for number of fruits per plant in cross C5 (23.68%) and C1 (8.13%) over better parent and cross C5 (79.48%), C6 (60.51%), C1 (56.92%) and C9 (41.03%) over standard parent and for fruit yield per plant cross C8 (45.50%), C5 (45.39%), C12 (33.53%) and C6 (30.42%) over better parent and cross C5 (51.82%), C1 (44.92%), C6 (44.17%), C4 (29.37%) and C3 (29.10%) over the check variety. The crosses C5 (23.68% and 79.48%) for number of fruits per cluster, C8 (50.72%) and C4 (49.46%) for single fruit weight showed significantly high percentage of positive heterosis over better and standard parent, respectively. The cross C1 (-28.91%), C10 (-31.25%), C6 (-20.56%) showed negative heterosis for days to first flowering. Based on the desired morphological traits and heterosis manifestation of the yield attributing traits of the F 2 population, the cross combination C1, C5, C6, C8, could be selected for further improved and advancement of the lines to develop stable inbred lines for future tomato breeding program.