Effects of Gibberellic acid and 2,4-Dichlorophenoxy Acetic Acid Spray on Vegetative Growth, Fruit Anatomy and Seed Setting of Tomato ( Lycopersicon esculentum Mill. )

The experiment was conducted at Melkassa Agricultural Research Center, Ethiopia with the objective to evaluate the effects of different  concentrations and combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and gibberellic acid (GA3) spray on vegetative and reproductive growth components of tomato. The experiment consists of two tomato varieties, one processing (Roma VF) and one fresh market (Fetan), three levels of 2,4-D (0, 5 and 10 ppm) and four levels of GA3 (0, 10, 15 and 20 ppm) arranged in 2x3x4 factorial combinations, in Randomized Completed Block design with three replications. Data were collected on qualitative  parameters (vegetative, reproductive growth and external fruit color) through visual observation, and quantitative parameters (seed number per fruit, seed weight per fruit, fruit shape index and average fruit weight). Qualitative data were analyzed using analysis of variance (ANOVA) by SAS (2002) software and mean separation was carried out by DMRT at 5% probability level. The result indicated that tomato plant treated with 2,4-D intended to have increased stem thickness, decreased leaf size induced epinastic and flower bud abscission in both cultivars while GA3 treatment has no retarded growth and flower bud abscission. Application of 2,4-D has responsible in the development of seedless parthenocarpic fruit with  increased size but with unfilled cavities especially at higher concentration. On the other hand, GA3 at lower concentration results in normal fruit and seed development but as its concentration increases it results in the development of more proportion of smaller fruits per plant and formation of blotchy ripening on the fruit. Combined application of the two PGRs at lowers concentrations seems to result in the intermediate effects of both PGRs in single application. In general, concentration of the PGRs used and genetic background of the variety determine the response of tomato growth, fruit setting, seed formation and final marketable fruit size.