Articles
LEAF BLACKENING IN CUT PROTEA EXIMIA: IMPORTANCE OF WATER RELATIONS
Protea eximia, the Rose-spoon protea, shows very rapid leaf blackening.
The use of Floralife preservative before and after simulated shipping, shipping temperatures, and packaging in plastic bags was investigated.
The use of Floralife (20 g/l) delayed leaf blackening and wilting of the flower over the use of deionized water only for all temperatures.
The use of a preservative allowed warmer shipping temperatures, as at 13°C, Floralife was as good as or equal to water at 2° or 7° shipping temperatures.
If the flower stems were held in a plastic bag rather than dry in a box and supplied with preservative prior to and after shipping, even the 20° shipping temperature allowed as much delay to 50% leaf blackening as did dry shipping with no preservative use at 7°C.
Clonal differences were observed in the rate of leaf blackening.
As much as 20% difference in the time to 50% leaf blackening was observed among clones in both water and preservative.
Even when preservative slowed the rate of leaf blackening, the flower could still wilt.
Water loss from the flower varied from 25 to 50% of the water loss from a leafy stem with flower.
Removal of the flower had a delaying on the development of leaf blackening.
This is not at variance with a hypothesis that water loss through the flower head causes a water stress which triggers the blackening reaction.