LIGHT ENVIRONMENT EFFECTS ON CHLOROPHYLL CONTENT IN AGLAONEMA-COMMUTATUM

The effects of light intensity and light quality on chlorophyll content and chlorophyll a:b ratio in the obligate shade plant Aglaonema commutatum were studied. Three light intensities (2.7, 5.4 and 20.0-mu-mol m-2 s-1) provided by two light sources (fluorescent and blended-light lamps) were tested on plants of two sizes under controlled environments. There was an increase in chlorophyll content at low light intensity when the larger 'size A' plants were used, but no differences between 2.7 and 5.4-mu-mol m-2 s-1 in the smaller 'size B' plants. The different experimental results were related to the scarcity of assimilates in 'size B' plants. Light quality had no effect on chlorophyll a+b content. At low intensity, the chlorophyll a:b ratio was only slightly lower in A. commutatum plants grown in far-red enriched environments, which suggest that a mechanism that does not require changes in the proportion of chlorophyll a related to b may be operating to balance the supply of quanta to both photosystems.