LEAF BLACKENING IN PROTEAS
The postharvest blackening of leaves of cut flowers of Protea eximia was not affected by treatments reducing transpiration or applying moderate water stress, but was exacerbated when the flowers were held under low light and high temperature conditions. Removal of the inflorescence, placing the flowers in high light conditions, or girdling the stem immediately below the inflorescence delayed or eliminated leaf blackening. These data suggest that competition for carbohydrate rather than water stress is a major cause of leaf blackening in cut stems of Protea eximia.
Reid, M. S., Doorn, W. and Newman, Julie P. (1989). LEAF BLACKENING IN PROTEAS. Acta Hortic. 261, 81-84