关键词:
AGRICULTURE
PLANTS
摘要:
The growth cabinet used can be run at any temperature from 40 F. to 75 F.2 F., by circulating air past a heater and a thermostatically controlled cooler. There is no water screen between the lights and the plants. The evenly illuminated area is 5 sq. ft. ; it receives light from twelve 150-watt tungsten filament reflector spotlamps and twelve experimental 30-watt, 3-ft., blue fluorescent tubes. These lamps provide a continuous spectrum which, compared with sunlight, is slightly weaker in green and stronger in blue and red. The present maximum intensity at the level of the plants, 18 in. from the lamps, is equivalent to sunlight at 2,000 foot-candles. Below each tungsten bulb is a disk of Chance's 'O.N.20' heat-absorbing glass 6 in. in diameter. Even when more than two kilowatts are being put into the lamp circuit, it has been necessary to switch on an 80-watt heater to maintain cabinet temperature at 70 *** are being carried out. on strains of Lolium under this light intensity. The evidence to date does not suggest that 2,000 foot-candles is the maximum to which Lolium will respond, and arrangements are being made to increase the light intensity still *** the design of the lighting arrangements particular thanks are due to Dr. J. N. Aldington, of Siemens, Ltd.