Articles
SENESCENCE AND SUGAR STATUS OF THE CUT FLOWER
When the flower is cut the rate at which sugar is metabolized is one of the factors that determines its longevity.
The sugar content can be maintained by feeding sugar solutions through the cut stem, but the extent to which the longevity of the flower is increased is not the same for all species.
This paper describes the quantitative changes in the ethanol-soluble sugars of petals of carnations (‘White Sim’) and narcissus (‘Actaea’), examples of cut flowers which respond differently to treatment with sugars.
The principal sugars in the corolla of the carnation are reducing sugars and sucrose; the former predominate at all stages of flower development.
During senescence the total sugar declines until about half of the initial weight of reducing sugar remains at incipient wilting whereas sucrose practically disappears.
In narcissus the ratio of the concentration of sugars depends on the stage at which the flower is cut.
At the "goose-neck" stage, reducing sugars are present in smaller amounts than sucrose but during flower development and senescence, reducing sugars increase to a maximum, roughly coincident with full flower opening, and then decrease until half of the maximum remains at wilting; sucrose disappears as the reducing sugars increase.
Feeding carnation flower buds with sucrose causes an accumulation of reducing sugars in the petals and the life of the open flower is very nearly doubled; the same treatment applied to narcissus causes only a small improvement in longevity but results in substantial growth of the ovary.
The findings lend support to the concept that the cut flower is a metabolically active centre and that complex translocation phenomena are involved during senescence.