2008 年 52 巻 3 号 p. 69-73
Attempts were made to apply Paclobutrazol (PBZ) to 3-year-old ‘Irwin’ mango trees in order to alleviate the sparse flowering of ‘Irwin’ for fruit production in Okinawa under plastic house conditions. The study was conducted in Ishigaki, Okinawa Prefecture. Two flushes were observed after pruning in May 2006, and PBZ was applied in July of that year when the leaves were expanding after the second flush. On July 1, PBZ was applied to soil by drenching at a rate of 1 g a.i. per tree, or as a foliar spray at the rate of 1500 ppm. In the PBZ-treated trees, bud break occurred 18-22 days earlier than in the control trees. Apical bud breaking exceeded 98% in the PBZ-treated trees compared with only 42% in the control trees. More than 96% of the PBZ-treated trees produced floral shoots, compared with only 35% of the control trees. The panicles of the PBZ-treated trees, were shorter than those of the control trees. Fruit yield per tree was higher in the PBZ-treated trees than in the control trees. The Brix value and titratable acidity of the fruits did not differ among the treatments.