Effects of Paclobutrazol on Non-enzymatic and Enzymatic Antioxidants during Floral Bud Development in Mango (Mangifera indica L.) cv. Totapuri

Abstract

A study was conducted to investigate the effects of paclobutrazol (PBZ) (1.25 g a.i m-1) on the contents of non-enzymatic antioxidants, ascorbic acid, glutathione (GSH) and phenols and activities of antioxidant enzymes, peroxidase, catalase, superoxide dismutase and ascorbate peroxidase in buds and leaves of growing shoots of mango cv. Totapuri at four distinct phenological stages numerically represented as 510 (initiation of bud swelling), 511 (Swollen buds), 513 (bud burst) and 515 (panicle emergence) as per BBCH scale. The paclobutrazol treatment increased in non-enzymatic antioxidants, ascorbic acid (5.0487.61%), total phenol (5.74-65.65%) and GSH (5.08-38.7%) contents buds and leaves and activities enzymatic antioxidants, peroxidase (33.0-266.9%), SOD (44.3-198.0%), catalase (68.0-301.6%), and ascorbate peroxidase (22.8-99.0%) in buds at various phenological stages. The paclobutrazol induced increase in ascorbic acid and GSH was high at 511 and in total phenols at 513 stages in the developing buds. With respect to bud growth stages, activities of enzymatic antioxidants, peroxidase and ascorbate peroxidase were high at 511 stage and the SOD activity at 510 stage under paclobutrazol treatment. The catalase activity witnessing consistently increasing trends in developing buds was high at panicle emergence (515 stage). There was broad similarity in the trends of non-enzymatic and enzymatic antioxidants antioxidant contents in the developing buds of paclobutrazol untreated and treated trees. From the results, it was apparent that the mango flowering coincides with increase in non-enzymatic and enzymatic antioxidants, and a high antioxidant status induced by paclobutrazol is responsible for its floral responses.