THE EFFECT OF SPECTRUM CONVERSION COVERING FILM ON CUCUMBER IN SOILLESS CULTURE

It is known that the effective wavelength range of light for photosynthesis is 400-700 nm, and that assimilation in the red region is higher than in other regions. Recently, we harnessed this characteristic for the development of a spectrum conversion covering film which changes light from the low active region (green light) for photosynthesis to the effective region (red light). The effect on plant growth of conversion film changing sunlight to the red region had not been clarified because of the difficulty of developing a lasting weather resistant spectrum conversion film. We improved the film and carried out studies on nursery stage vegetables. In this experiment we used a cucumber crop, in which the quantity of photosynthesis is greatly influenced, since the growth rate of the plant and fruit is fast, and investigated growth, yield, and nutrient absorption under the spectrum conversion covering film. The results show that total yield, growth and fruit dry matter rate of cucumbers grown under the spectrum conversion covering film were greater than for cucumbers grown under non-conversion film, but there was no difference in fruit length, level of bent fruit and average fruit weight between the two films. The P concentration in the 10^th leaf and in the fruit under the spectrum conversion covering film was higher than under the non-conversion film. The concentrations of other mineral elements under the spectrum conversion covering film tended to be higher than under the non-conversion film. The light transmission characteristics of covering conversion film did not change after 42 months. The spectrum conversion covering film is effective for stable cucumber production because of high yield and good nutrient absorption.