GROWTH OF VEGETABLES SUSPENDED UPSIDE DOWN

It is necessary to arrange plants effectively in a plant factory, in order to reduce the lighting cost for the practical cultivation with artificial lighting.
In this study, rooting beds were arranged above and below an array of fluorescent lamps.
Plants at the lower plot were grown upward and plants suspended upside down at the upper plot were grown downward.
The rooting material used was rockwool.
The effects of the light intensity on growth of three species of vegetable crops at the both plots were investigated.
Additional six species were grown at a PPFD level of 200 μmol·m^-2·s^-1 and differences between the growth characteristics at the both plots were observed.

As a result, the growth rates of the lettuce, the welsh onion, the turnip and the radish suspended upside down at the upper plot were similar to those of upward grown plants at the lower plot, when the PPFD level was more than 200 μmol·m^-2·s^-1. On the other hand, the stems of the kidney bean, the tomato, the egg plant, the pimento and the cucumber at the upper plot curved upward, and their growth rates were significantly smaller than those at the lower plot.
Such a tendency was also observed even at higher PPFD levels.

It was proved that the rosette type plants which had short stems such as lettuce and radish could be cultivated upside down in this method, when the PPFD level was more than 200 μmol·m^-2·s^-1.

Protected Cultivation, XXIII IHC

Y. Kitaya, M. Kiyota, T. Imanaka, I. Aiga

https://doi.org/10.17660/ActaHortic.1992.303.10