Efficient Methods for Pollen Harvesting in a Japanese Pear Pollinizer (I)

Since most of main commercial cultivars of Japanese pear (Pyrus pyrifolia Nakai) are self-incompatible, supply of pollen and artificial pollination is required. To promote pollen production efficiency, we investigated flower bud harvesting methods, training of trees and plant growth regulator treatments. Simultaneous harvest at 50% of full bloom was the most efficient. Among training systems, tree joint training, in which main stem of each tree were bent horizontally at 70 to 90 cm height, and tips were grafted into the adjacent tree, increased the number of flower buds compared to stand-alone non-bent trees, or horizontally bent non-grafted trees. The efficiency of hand harvest of flower buds was higher in joint trees than in stand-alone non-bent trees, or flat trellis trees. In ‘Shinko’ pear trees, the number of flower buds increased by the gibberellin biosynthesis inhibitors (daminozide and paclobutrazol), and the synthetic ethylene (ethephon) application in shoot growth period. In conclusion, simultaneous harvest at 50% of full bloom and tree joint training system were efficient, and daminozide, paclobtrazol and ethephon treatments were effective for promotion of flower buds of ‘Shinko’ pear trees.