Manipulation of the annual growth cycle of blueberry using photoperiod.

摘要

A controlled environment study was conducted using container-grown 'Duke', 'Bluecrop' and 'Elliott' from July to December 2002 in Corvallis, Oregon. Plants were placed in growth chambers (GC) under either short-day (SD, 8 h of light) or long-day (LD, 16 h of light) photoperiod and constant temperature (22 degrees C) for up to eight weeks. Every two weeks, a group of plants was moved from the GC to a greenhouse (16 h light, 22 degrees C) to measure dormancy, growth, and percentage of flower buds. After eight weeks of SD, a group of dormant plants were moved from the GC to a cold room (4 degrees C) for 900 hours, and then transferred back to the GC (LD and 25 degrees C) to record days to bud break, bloom and fruit ripening. Plants under LD had three to six flushes of growth and did not initiate flower buds or enter endo-dormancy. Bud break occurred after 5 to 15 days in the greenhouse. Plants under SD had two flushes of growth and developed flower buds after two weeks of SD and dormancy after four weeks of SD. The number of flower buds and the degree of dormancy increased with time of exposure to SD. After cold storage, bud break and bloom occurred after 6 and 26 days, respectively, with little differences among cultivars. Fruit harvest started 65, 95, or 130 days after bud break in 'Duke', 'Bluecrop', or 'Elliott', respectively. Fruit set in the GC was reduced due to insufficient pollination..