Physiological,biochemical, antioxidant and growth characterizations of gibberellin and paclobutrazol-treated sweet leaf (<Emphasis Type="Italic">Stevia rebaudiana</Emphasis> B.) herb

A greenhouse experiment was designed to study the responses of Stevia rebaudiana herb to paclobutrazol (PBZ) and gibberellin (GA) treatments. GA and PBZ treatments caused no significant impact on photosynthesis pigments while they increased carbohydrates, amino acids and protein metabolites. Stevia showed a potent antioxidant activity through scavenging DPPH, NO^·; O ₂ ^·? and OH^· radicals which was highlighted in GA and PBZ treatments. The enzymatic and non-enzymatic antioxidant system of Stevia plant showed a significant increase in response to PBZ and GA treatments. PBZ treatment decreased plant growth while GA treatment had no significant effect on it. Collectively, both GA and PBZ treatments effectively increased metabolites and antioxidant property of Stevia herb.