ISHS Acta Horticulturae 514: XXV International Horticultural Congress, Part 4: Culture Techniques with Special Emphasis on Environmental Implications
EFFECT OF RED/FAR-RED PHOTON FLUX RATIO OF SOLAR RADIATION ON GROWTH OF FRUIT VEGETABLE SEEDLINGS |
| Authors: | M. Takaichi, H. Shimaji, T. Higashide |
| Keywords: | covering film, raising seedlings, light spectrum, red/far red photon flux ratio |
| Abstract:
Muskmelon, tomato and cucumber seedlings were examined to clarify the effect of red/far-red photon flux ratio (R/FR) of solar radiation changed by covering materials. Effects of the light treatments on plant height became apparent in a few days for all crops examined. The high R/FR treatment inhibited stem and petiole elongation but the low one promoted them. The effect of changing R/FR was larger in muskmelon seedlings than that of tomato. Leaf emergencies and leaf sizes were almost the same among the treatments. Although stem and petiole lengths of the seedlings differed largely at the end of the treatments, no differences were seen in the consequent stem growth, flowering and fruiting after transplanted into normal conditions. The effects of changing R/FR occurred with small time lags and had no residual effects. Dry matter production was usually reduced by covering of colored materials. For cucumber seedlings, the effects of short time coverings in daytime on stem elongation were investigated. Degree of stem elongation was approximately proportional to estimated mean R/FR during daytime in the R/FR range of 0.8 to 2.0. Differences of the effects in the treated time of day were not apparent. These characteristics are convenient for plant height control because no strict adjust of light environment are required. The changing R/FR of solar radiation by covering could be applied to control the shoot morphology for the fruit vegetable seedlings. | |
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