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Abstract
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The apple (Malus domestica Borkh) is an important fruit crop and a focus of horticultural research. Flower formation in apple involves a long multi-step process, which can be recognized on the basis of histological and morphological differences of shoot apex. In the present study, buds and spur leaves were harvested from 6-year-old uniform-sized apple (cv. Red Delicious) trees grafted on MM-106 rootstock and trained to a central leader. Buds and spur leaves were sampled at 45, 60, 75, 90, 105 days after full bloom (DAFB). Superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) specific activities were determined in crude protein extracts prepared from 0.1 g dry weight of plant material. According to the microscopic and biochemical results, the highest activity in APX, GR and SOD was achieved in 60 days after full bloom, and therefore this time is very important in transition to flowering. On the basis of these results, we suggest that antioxidant enzymes are one of the candidate factors for transition to flowering.
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