Low-temperature storage of rooted chrysanthemum cuttings: relationship to carbohydrate status of cultivars

Low-temperature storage potential of rooted cuttings of garden chrysanthemum [Dendranthema X grandiflorum (Ramat.) Kitamura] cultivars and its relationship with carbohydrate reserves were evaluated. Storage of chrysanthemum cuttings at -1 and -3 degrees C resulted in freezing damage. Visual quality of rooted cuttings stored at 0 or 3 degrees C varied among cultivars. Quality of 'Emily' and 'Naomi' cuttings was reduced within a week by dark storage at 0 or 3 degrees C due to leaf necrosis, while 'Anna' and 'Debonair' cuttings could be held for 4 to 6 weeks without significant quality loss. In 'Anna' and 'Debonair', low-temperature storage reduced the number of days from planting to anthesis regardless of storage duration. However, flowers of plants grown from stored cuttings were smaller than those of nonstored cuttings. At the beginning of storage, 'Emily' and 'Naomi' had lower sucrose, glucose, and fructose (soluble sugars) content compared to 'Anna' and 'Debonair'. Regardless of temperature, leaf soluble sugar was significantly reduced by dark storage for 4 weeks. In stems, sucrose and glucose were reduced while fructose generally increased during low-temperature storage probably due to the breakdown of fructans. Depletion of soluble sugars and a fructan-containing substance during low-temperature dark storage was greater in 'Emily' and 'Naomi' than in 'Anna' and 'Debonair'. Low irradiance [about 10 micromoles.m-2.s-1 photosynthetically active radiation (PAR) from cool-white fluorescent lamps] in storage greatly improved overall quality and delayed the development of leaf necrosis in 'Naomi'. Cuttings stored under light were darker green and had a higher chlorophyll content. Leaf and stem dry weights increased in plants stored under medium and high (25 to 35 micromoles.m-2.s-1 PAR) irradiance while no change in dry weight was observed under dark or low light. Results suggest that the low-temperature storage potential of chrysanthemum cultivars varies considerably, and provision of light is beneficial in delaying the development of leaf necrosis and maintaining quality of cultivars with short storage life at low temperatures.