GROWTH OF DENDRANTHEMA XGRANDIFLORUM (RAMAT) KITAMURA UNDER VARIOUS SPECTRAL FILTERS

'Spears' (nonpinched and pinched) and 'Yellow Mandalay' (pinched) chrysanthemums were grown in growth chambers equipped with panels filled with liquids that served as spectral filters. Light quality was altered by reducing blue light, increasing red : far-red (R : FR) light, or reducing R : FR. Control panels did not selectively . alter light transmission. Photosynthetic photon flux was the same in all chambers. All plants grown under increased R : F; filters had reduced height, reduced internode length, and increased chlorophyll content compared to controls. Reduction in blue light decreased chlorophyll content of pinched plants compared to controls. Pinched plants grown under increased R : FR light and long days developed fewer nodes than controls due to the formation of abnormal capitula; the controls and plants from the other treatments developed more nodes before producing similarly abnormal capitula. Stem diameter and leaf area did not differ due to treatments.