ISHS Acta Horticulturae 418: III International Symposium on Artificial Lighting in Horticulture
QUANTIFYING THE INFLUENCE OF HIGH-PRESSURE SODIUM LIGHTING ON SHOOT-TIP TEMPERATURE |
| Authors: | James E. Faust, Royal D. Heins |
| Abstract:
Vinca (Catharanthus roseus L.) plants were placed in a growth chamber under high-pressure sodium (HPS) lamps to quantify the effect of supplemental lighting at 0, 50, 75, or 100 μmol m-2 s-1 photosynthetic photon flux (PPF) on shoot-tip temperatures. PPF treatments were delivered at air temperatures of 15, 20, 25, and 30°C and at vapor-pressure deficits (VPD) from 0.5 to 3.0 kPa. The temperature of plants receiving 50, 75, and 100 μmol m-2s-1 was 1.2, 1.5, and 1.7°C higher, respectively, than that of plants in the dark, regardless of VPD. Relative to air temperature, plant temperature decreased 1.2°C as the VPD increased from 0.5 to 3.0 kPa at each PPF level. A polycarbonate/water filter was used to reduce the long-wave radiation incident on the plant canopy. At 100 μmol m-2s-1, plants under the polycarbonate/water filter were 2.7°C cooler than those grown at the same PPF without the filter. Supplemental lightning's effect on plant temperature and developmental rates will be discussed. | |
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