Abstract
Three growth cabinets were constructed using the following PMMA (poly-methyl methacrylate) as covering materials: 1) Red light (R) interceptor (R-intercepting dyestuff added) . 2) Normal (no dyestuff added) . 3) Far-red light (FR) interceptor (FR-intercepting dyestuff added) . R/FR (600-700/700-800 nm) photon flux ratios in R-intercepted, normal (control) and FR-intercepted cabinets were 0.53, 1.16 and 1.50 respectively. The seedlings of sunflower (Helianthus annuus L. cv. Russian Mammoth) and cabbage (Brassica oleracea L. cv. Suehiro Kanran) were cultivated in the cabinets under the same conditions of PPFD and other environmental factors. For both kinds of plants, elongation of the seedlings were significantly promoted in the R-intercepted cabinet, and inhibited in the FR-intercepted cabinet, compared with the seedling in the normal cabinet. Slight changes were also observed in other morphological characteristics. After ten days of treatment in their respective cabinets, the sunflower seedlings were transplanted into a natural greenhouse, and it was shown that they gradually recovered to the same growth state as under the control treatment. The experimental result suggested that these covering materials would be effective in controlling plant elongation in greenhouse cultivation for many kinds of crops.
