GROWTH AND MORPHOGENESIS OF LETTUCE SEEDLINGS RAISED UNDER DIFFERENT COMBINATIONS OF RED AND BLUE LIGHT

The purpose of our study was 1) to develop new types of plant growing apparatus using light emitting diodes (LEDs), and 2) to evaluate the possibility of using LEDs as an artificial light source for plant growth.
In this report, the effects of different ratios of red and blue (red/blue) photosynthetic photon flux density (PPFD) levels at equal PPFD on the growth and morphogenesis of lettuce seedlings were investigated.
Lettuce seedlings (Lactuca sativa L. cv.
Okayama-saradana) were hydroponically grown for fourteen days under eight different ratios of red/blue PPFDs at a total PPFD of 60μmol/m²/s, or under four different ratios of red/blue PPFDs at a total PPFD of 80μmol/m²/s.

Stem elongation of the lettuce seedlings was accelerated by red/blue PPFD ratios of 54/6 and 48/12, and whole plant dry weight was a maximum at a red/blue PPFD ratio of 48/12. Stem length was significantly decreased with an increase in the blue PPFD. Although growth of whole plants was accelerated by a red/blue PPFD ratio of 64/16, maximum values of root and stem dry weight occurred at red/blue PPFD ratios of 56/24 and 72/8, respectively.

II Workshop on Environmental Regulation of Plant Morphogenesis

K. Okamoto, T. Yanagi, S. Kondo

Lactuca sativa L., light emitting diode, LED, artificial light source

https://doi.org/10.17660/ActaHortic.1997.435.14