ISHS Acta Horticulturae 174: Symposium Greenhouse Climate and its Control
PLANT GROWTH UNDER AVERAGED DAY/NIGHT TEMPERATURES |
| Authors: | W.B. Miller, L.D. Albright, R.W. Langhans |
| Abstract:
'Grand Rapids' lettuce was grown from seed in growth chambers under three exotic temperature regimes. Air temperatures were 1) increased from 15° to 35°C (late-peak); 2) decreased from 35° to 15°C (early-peak), and 3) increased to 35°, then back to 25°C (mid-peak), each during the 16 hour light period. Each pattern averaged 25°C day, and 20°C night temperature. Plant growth was equivalent under the mid- and late-peak patterns, whereas the early-peak pattern was detrimental to growth. Leaf area was an especially sensitive indicator of the detrimental effects of early morning elevated temperatures. Leaf diffusive resistance was essentially independent of air temperature pattern. Three Chrysanthemum cultivars ('Bright Golden Anne', 'Jackstraw' and 'Yellow Nob Hill') were grown under baseline (25/20°C day/night) conditions or the mid-peak (25/20° average day/night, above) pattern. While cultivar differences occurred, general results indicate positive response to the mid-peak average temperature pattern. Shifting plants between growth chambers every few days appears to be a relatively easy method to avoid 'chamber effects' on plant growth. | |
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