Journal of Experimental Agriculture International

Field experiments were conducted to estimate the combining ability and nature of gene action governing inheritance of characters in tomato (Lycopersicon escullentum Mill) under high temperature stress. The experiment was conducted at the Teaching and Research Farm of Department of Crop Production and Horticulture Modibbo Adama University of Technology, Yola. (latitude 9° 18¹ N and long 12° 15¹ E) and the Teaching and Research Farm of Adamawa State University, Mubi (latitude 10° 03¹ N and long. 13° 07¹ E) all in Adamawa state of Nigeria. Fourteen entries consisting of six parents and eight croses developed by crossing two males (testers) and four females (lines) following line x tester design were evaluated in three replications in a Randomized Complete Block Design (RCBD) in two locations. Ten plants were randomly sampled for recorded observation. Data were collected from the following characters; Trichome count, plant height at 60DAT, number of leaves per plant at 60DAT, number of fruits per plant, weight of fruits per plant % damaged fruits and number of days to final harvest. Data were subjected to biometrical analysis. Result of the analysis of variance indicated highly significant difference for all characters among entries except weight of fruits per plant. The result suggested the presence of genetic variability among the tomato genotypes under study. Significant difference were observed in the combining ability analysis of variance in all the agronomic characters under study except for trichome count suggesting both additive and non-additive genetic effects were important in  governing  this characters under study with more preponderance of additive effects. The cultivars, Cherry, Currant, UC28B, and RomaVF were identified as the best general combiners and the best yielders in terms of number of fruits per plant with appreciable tolerance to heat damage.