ISHS Acta Horticulturae 587: International Symposium on Asian Pears, Commemorating the 100th Anniversary of Nijisseiki Pear
ADVANCING HARVEST OF JAPANESE PEAR THROUGH DORMANCY BREAKING TREATMENTS UNDER FORCING CONDITIONS |
| Authors: | K. Kisaki, N. Nishimoto, K. Sano, O. Kumamoto, Y. Hashiguchi, N. Sakaguchi |
| Abstract:
Earliest harvest of field-grown Japanese pears in Kagoshima prefecture occurs in late July to early August on ‘Chikusui’. To further hasten the harvest time, forcing culture was tried under a heated plastic house and dormancy breaking treatments. Treatment with chemicals to break dormancy: Three-year-old ‘Kousui’ trees in 70-liter pots were utilized. The potted trees were moved into a glasshouse at a max temp. of 28oC and a min. temp. of 20oC at two developmental stages: DVI1=0.8 before dormancy break and DVI1=1.0 at the completion of dormancy, where DVI1 is defined as a developmental stage calculated by an estimation model for breaking dormancy (Sugiura and Honjo, 1997). Upon moving into the glasshouse, trees were immediately treated with 1.39 and 2.78% calcium cyanamide, painted on all buds and twigs. Flowering and harvesting were examined. Growth under heated plastic house with dormancy breaking treatments: Twelve-year-old ‘Chikusui’ and 15-year-old ‘Kousui’ were utilized. On December 22, 1999 when the trees reached DVI1=0.8 in the field, 2.78% calcium cyanamide solution was sprayed on the whole trees. On December 24, vinyl film was covered over the trees and on Dec. 27 heating started. Minimum temperature was kept above 20oC during the start of heating to force bud break, and again from full bloom to 33 days later, but minimum temperature was kept above 15oC over the remaining period. Artificial pollination was performed during mid and late January with stored ‘Housui’ pollen. Flowering and sprouting was examined. Harvest was performed when ground color reached 4 by a color chart, and the quality was determined. | |
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