ISHS Acta Horticulturae 262: V International Symposium on Rubus & Ribes
FREEZING AVOIDANCE BY SUPERCOOLING IN FLORAL BUDS AND CANES OF 'SHAWNEE' BLACKBERRY |
| Authors: | M.R. Warmund, M.F. George |
| Abstract:
Differential thermal analysis (DTA) experiments and viability tests were conducted to study the biophysics of freezing in 'Shawnee' (Rubus sp.) floral buds and stem tissues from 14 October 1987 to 15 March 1988. One to three sharp low temperature exotherms (LTEs) associated with the crystallization of supercooled water were detected in over-wintering floral buds. These exotherms were correlated with low temperature injury to bud primordia. As many as nine floral primordia were observed in primary buds and one floral initial was observed in secondary buds. This indicates that a small number of ice nucleating events within the primary bud result in ice propagation into all floral primordia. A broad LTE was detected in stem tissue and was correlated with xylem injury. T50 values calculated from viability tests were within 3.2°C of the temperature at half the LTE peak area. Bark injury did not appear to be associated with a LTE. | |
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