Relationship of Low Temperature Exotherms to Cold Injury in Vitis Riparia Michx

Abstract

The relationship between low temperature exotherms (LTE) and tissue viability was investigated in Vitis riparia, using the technique of differential thermal analysis (DTA). Buds exhibited one or two LTE at most times during the winter. The occurrence of LTE was always associated with death of a bud. Buds may have the capacity to dehydrate during midwinter and thus avoid freezing damage.

Canes exhibited numerous LTE. At fast cooling rates, one exotherm was associated with injury to xylem tissue, and two with injury to phloem tissue. Both buds and canes which had been previously killed by freezing exhibited LTE when thawed and refrozen. Therefore, it is concluded DTA is not a valid test for tissue viability in this species.