CARBOHYDRATE STATUS OF CUSO4 SPECTRAL FILTER-GROWN CHRYSANTHEMUM PLANTS

Abstract

The response of `Bright Golden Anne' chrysanthemum plants grown under CuSO4 spectral filters to exogenous GA3 application was evaluated to determine the relationship between gibberellins (GAs) and carbohydrate levels. The CuSO4 filters removed far red (FR) wavelengths of light and increased red: far red (R:FR), blue: far red (B:FR), blue: red (B:R) ratios, and phytochrome photoequilibrium (Ø) values of transmitted light compared to water (control) filter. Plant height, internode length, and leaf and stem dry weights were significantly reduced by light passing through CuSO4 filters in spring and summer seasons. Weekly applications of exogenous GA3 reversed the reduction in height and internode length induced by CuSO4 filters. Plants grown under CuSO4 filters responded more to exogenous GA3 application with respect to height and internode length, suggesting that the sensitivity to GA was not lowered. Light passing through CuSO4 filters reduced the carbohydrate levels, but the response varied with the season. Weekly GA3 application increased the carbohydrate levels, but did not totally reverse the reduction in carbohydrate levels under the CuSO4 filters. Although GA3 application increased the carbohydrate levels partially in CuSO4 filter-grown plants, the inhibition of GAs may not be solely responsible for reduction of carbohydrate levels under CuSO4 filters, showing that exogenous GAs and carbohydrate levels are not well correlated under CuSO4 spectral filters.