Effect of paclobutrazol and gibberellin on yield, essence content and antioxidant activity of sweet pepper (Capsicum annuum)

Nowadays, plant growth regulators are widely used as growth stimulants in different plants production. For this purpose, an experiment was conducted as greenhouse and in a completely randomized design with four replications. Experimental treatments consisting of gibberellin and paclobutrazol growth regulators in seven treatments included off without the use of growth regulators, full use of gibberellin (100 mg.L-1), full use of gibberellin + use of 50% paclobutrazol, full use of gibberellin + full use of paclobutrazol, use of 50% gibberellin + full use of paclobutrazol, use of 50% gibberellin + use of 50% paclobutrazol and full use of paclobutrazol (150 mg.L-1). The results showed that full use of gibberellin + full use of paclobutrazol compared to control treatment (without the use of growth regulators) improves plant quantity traits such as plant fresh and dry weight, fruit yield and fruit number per plant. However, the lowest activity of the antioxidant enzymes of superoxide dismutase and ascorbate peroxidase was obtained from the application of the same treatment. The results of a separate comparison of the two growth regulators used in this experiment also indicated that in all studied traits except plant height the use of paclobutrazol plant growth regulator had a more favorable effect on the mentioned traits compared to gibberellin. In this experiment, the lowest amount of studied traits except fruit weight per plant was obtained from the control treatment. In addition, none of the plant growth regulators hadn’t any significant effect on the essence content of the plant.