Regulation of tomato (Lycopersicon esculentum Mill.) fruit setting and earliness by gibberellic acid and 2,4-dichlorophenoxy acetic acid application

Abstract

The experiment was conducted with the objective of determining the effects of different concentrations and combinations of the plant growth regulators (PGRs) 2,4-dichlorophenoxyacetic acid (2,4-D) and gibberellic acid (GA₃) spray on fruit setting and earliness of tomato varieties. The experiment consisted of one processing (Roma VF) and one fresh market (Fetan), tomato varieties, three levels of 2,4-D (0, 5 and 10 ppm) and four levels of GA₃ (0, 10, 15 and 20 ppm) arranged in a 2 × 3 × 4 factorial combinations, in randomized completed block design with three replications. The study indicated that application of 2, 4-D at 5 and 10 ppm hastened flowering and fruiting but reduced number of fruits per cluster, fruit set percentage and final marketable fruit number per plant. However, application of GA₃ extended flowering and maturity time and increased fruit number per cluster, fruit set percentage and marketable fruit number per plant over the control. In general, the study indicated that 2, 4-D is important in tomato production to induce fruit setting and earliness and GA₃ seems to extend fruit maturity and harvest period while the combined applications have intermediate effects. Therefore, it is important to further investigate the method of application and concentrations of these PGRs at different growing conditions and on different tomato cultivars to assess their role in tomato fruit setting and maturity time.

Keywords: Gibberellic acid, 2, 4-dichlorophenoxy acetic acid, tomato, Lycopersicon esculentum mill, fruit setting, fruit earliness