PERFORMANCE OF CUT 'SONIA' ROSES AS AFFECTED BY STEM COOLING
Limiting the cold treatment, by means of an adjustable cooling block, to the lowermost 2 ½ cm of stem, including the very cut surface, turned out to be definitely better than cooling a 5 cm portion a little higher up the stem, leaving the cut surface exposed to the ambient temperature.
In 0 °C-treated stems the resistance to water flow increased less rapidly than it did at 20 °C, especially in the lowest stem part.
These findings are discussed in relation to the 'vascular occlusion' concept. No unequivocal conclusion is reached; yet, this much is evident that some process occurring at the cut surface of the stem plays an essential role.