Search Results
You are looking at 1 - 3 of 3 items for
- Author or Editor: William Eisinger x
Abstract
Cytokinins delay the onset of senescence in cut carnation flowers (Dianthus caryophyllus) by affecting the biosynthesis and action of ethylene in the tissue. The onset of senescence is marked by an increase in ethylene sensitivity and production by the tissue. A characteristic rise in 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, accompanies the initial stages, but the greatest increases in ACC are associated with the decline in ethylene production during the later stages of senescence. Cytokinins delay the onset of senescence and reduce ethylene sensitivity and production. Benzyladenine (BA), a cytokinin, prevents the rise in endogenous ACC levels and reduces the capacity of the tissue to convert ACC to ethylene. The effects of other anti-senescence agents, aminoethoxy vinylglycine (AVG), silver ions and cobalt ions, are compared with those of BA on ethylene sensitivity and production. The mechanism of action of BA in the delay in flower senescence is discussed.
Abstract
The effects of pH, osmolarity, and oxygen content on solution uptake by cut flowers of Rosa hybrida L. cvs. Cara Mia and White Satin were investigated. Solution uptake was increased at low pH (below 3) while high pH (above 6) inhibited uptake; both effects were amplified with time. Solution uptake was altered by the composition of the buffer. Maximum vase life was achieved with pH 5 solutions. The rates of uptake of various floral chemicals correlated well with the pH values. Mannitol and high concentration of sucrose significantly inhibited total solution uptake but potassium chloride did not inhibit uptake. Deoxygenated solutions were taken up 45% more rapidly during the first 2 hours, but oxygen content had no significant effect on total uptake after 72 hours. High rates of solution uptake do not seem to be required for extension of cut rose vase life.
Abstract
The main evidence for a single mechanism of ethylene action is the observation that nearly all responses to the gas have the same dose response curve (8), suggesting a single type of receptor molecule. If so, the case is similar to that of phytochrome where one biochemical change produces a multitude of secondary changes resulting in a variety of physiological responses depending upon the tissue involved. We have chosen to use the etiolated pea seedling to investigate the primary and secondary actions of the gas because all parts of this plant have been extensively studied and are highly responsive to ethylene. When this seedling is exposed to ethylene stem growth slows, the hook tightens, the subapex swells and nutates horizontally, root growth slows and the zone of elongation swells, root hairs form, lateral root formation is inhibited, and the root tip bends plageotropically. The causes of these changes are to be found in the effects of ethylene on cell division, cell expansion, and auxin transport.