Supercooling in floral buds of 'Danka' black annd 'Red Lake' Red currants
1991
Warmund, M. | George, M. | Takeda, F.
Differential thermal analyses (DTA) and freeze viability tests were conducted to investigate the biophysics of freezing in floral buds of 'Danka' black (Ribes nigrum L.) and 'Red Lake' red currants [Ribes sativum (Rchb.) Syme] sampled from Nov. 1989 through Mar. 1990. Scanning electron microscopy was also used to determine the relationship between floral morphology and the freezing characteristics of the buds. Floral buds had multiple abrupt low-temperature exotherms (LTEs) and one or two broad LTEs in DTA tests. Abrupt LTEs from DTA were associated with apparent injury to the inflorescence in viability tests. The number of LTEs did not correspond to the number of racemes or flowers per bud, indicating that several flowers froze simultaneously. DTA experiments conducted in Dec. 1990 revealed that the broad exotherm detected between -14 and -20C in 'Danka' samples resulted from freezing of supercooled water in the outer nonliving region of the periderm of cane tissue attached to the bud.
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