PROHEXADIONE-CA MODIFIES CONTENT OF GIBBERELLINS AND VITAMIN C, ANTIOXIDANT CAPACITY AND ENZYMATIC ACTIVITY IN APPLE

The present research was conducted to better understand the effects of prohexadione-Ca (P-Ca) on the gibberellin changes at the apex and on the antioxidants and enzyme behavior on ripening fruits of apple (Malus ×domestica). P-Ca was sprayed twice in the spring of 2008 on sixteen-year old ‘Red Delicious’/ M.106 apple trees when shoot growth reached 5 cm in length. The concentration dosages of the growth retardant were 0 (control), 125, 175 and 200 mg•L^-1. The GC-MS analysis of experimental samples showed the presence of gibberellins A₉ and A₂₀ in P-Ca treated shoot tips; whereas gibberellins A₁, A₄, and A₇ were identified in control samples. The total antioxidant content in ripening fruits was increased with any concentration of P-Ca. A similar pattern was also observed in those fruits when vitamin C, catalase and peroxidase enzymes content were measured.