ISHS Acta Horticulturae 618: XXVI International Horticultural Congress: Environmental Stress and Horticulture Crops
EFFECT OF LIGHT QUALITY ON THE GROWTH OF LETTUCE IN LOW LIGHT |
| Authors: | T.A.O. Dougher, C.L. Moore, R.E. Gough |
| Keywords: | Lactuca sativa, photomorphogenesis, photoselective filters |
| Abstract:
Low light levels in greenhouses and growth chambers often produce poor quality plants. The roles of red and far-red light and phytochrome are well understood, but little is known about the effects of other wavelengths of photosynthetically active radiation. We examined growth of lettuce (Lactuca sativa) under filters of seven colors (blue, dark blue, teal, yellow, red, purple, and green) and sunlight (clear filter) at equivalent, low photosynthetic photon flux. Differences in angle of stem repose, hypocotyl elongation, and leaf length were apparent within 7 days after seedling emergence. Thirty days after planting, phytochrome photoequilibrium (PPE) was not a good predictor of plant stem elongation or dry mass response to the filters. Filters transmitting a high percentage of blue light, but lower PPE, produced plants that had fresh and dry mass equivalent to or higher than the control plants. Plants receiving low levels of blue light were etiolated (low chlorophyll and long stem length), with the degree of etiolation increasing as the amount of blue light decreased. | |
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