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Title: WATER STATUS OF BLUEBERRY FLOWER BUDS AND ITS RELATIONSHIP TO DORMANCY AND COLD HARDINESS

Author
item PARMENTIER, CECILE - CONTRACT EMPLOYEE
item Rowland, Lisa
item Line, Michael

Submitted to: Blueberry Research Extension North American Workers Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/27/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Previous investigations reported that in buds of woody perennials water is converted from a bound form to a freer form after the plants receive enough chilling to satisfy their chilling requirement. Therefore, the status of water could provide clues as to the mechanisms of maintenance and breaking of bud dormancy in woody plants. Experiments were conducted to evaluate the changes in water status, using Nuclear Magnetic Resonance, along with the changes in dormancy. Whatever the cultivar (Tifblue, Bluecrop, Gulfcoast), the state of water as well as the water content did not change with chilling accumulation and satisfaction of the chilling requirement. On the other hand, a transition to freer water occurred if the plants had received enough chilling to satisfy their chilling requirement and if they were placed at 24 degrees C for at least one day. The results suggested that bound water is more associated with cold hardiness than with dormancy. Also, NMR can be developed as a tool for scientists to distinguish buds that are strictly dormant (before satisfaction of the CR) from buds whose inability to break is imposed by environmental factors (CR is satisfied but not enough warm temperature to resume growth).

Technical Abstract: Previous investigations reported that water is bound while buds of woody plants are dormant and in a freer form after the chilling requirement has been satisfied. Therefore, the status of water could provide clues as to the mechanisms of maintenance and breaking of bud dormancy in woody perennials. Experiments were conducted to evaluate the changes in water status of blueberry flower buds, using Nuclear Magnetic Resonance (NMR), along with the changes in dormancy intensity, throughout the accumulation of chilling that leads to release from dormancy. Bluecrop was found to be the most dormant cultivar and Gulfcoast to be the least dormant. Tifblue had an intermediate dormancy. Under our experimental conditions, the chilling requirements (CRs) of Tifblue, Bluecrop and Gulfcoast were evaluated to be 1200 h, 1500 h and 140 h, respectively. Whatever the cultivar, the state of water as well as the water content did not change with chilling accumulation, even after CRs were satisfied. On the other hand, a transition to freer water, but no change in the water content, occurred if the plants were placed under forcing conditions. Forcing was ineffective in freeing water before the CR was satisfied. Results also suggested that bound water may be more associated with cold hardiness than with dormancy.