SPECTRAL FILTERS AND GROWING-SEASON INFLUENCE GROWTH AND CARBOHYDRATE STATUS OF CHRYSANTHEMUM

The interactions of light quality and growing season on growth and carbohydrate content of chrysanthemum [Dendranthema x grandiflorum (Ramat.) Kitamura] plants were evaluated using 6% CuSO4 and water (control) as spectral filters. Light transmitted through the CuSO, filter significantly reduced plant height and internode length compared to control plants regardless of the season. However, the degree of response varied with growing season. Light transmitted through CuSO, filters delayed flowering. Total number of flowers was not affected by spectral filter, but plants grown under CuSO, filter had smaller flowers than those grown under the control filter. Light transmitted through CuSO, filter resulted in reduced leaf and stem soluble sugar (sucrose, glucose, and fructose) and starch concentrations regardless of the growing season. However, the magnitude of reduction was greater in spring-than in fall-grown plants. Stems of fall-grown plants had more starch deposition than spring-grown plants under both filters. Filters with specific spectral characteristics can be used as alternative means of producing compact plants in the greenhouses, however, the delay in flowering and smaller flowers could limit their use for growth control of plants intended for flower production.