To increase the efficiency of double-truss tomato cultivation with root-zone restriction, a subirrigation nursery system with row-tray was developed and the growth of tomato seedlings was investigated. The row-tray, a plug-tray for producing seedlings, consists of twenty planting furrows. An irrigation drain sheet (IDS) was placed in five or seven furrows per tray, and both edges of IDS were hanging out of the furrows. After setting the root protection sheet (RPS) and substrate sheet (SS) into the furrows, three seeds were sown at the center of SS and one each 100 mm away from the center on both sides. The row-trays were placed on the subirrigation bed with a water retention sheet (WRS). When irrigation starts, nutrient solution is supplied from an irrigation pipe to WRS and is then sucked up from WRS to SS by IDS. Three tomato seedlings grown connected by SS could be planted to the hydroponics in a lump. Fewer total working hours were required to produce seedlings and planting them into row-tray system than for those using a plug-tray system. In the row-tray system, emergence, plant height and leaf number in IDS attached to the row-tray were greater than those in the non-IDS attached row-tray. There was no significant difference in terms of growth between SS and granular rockwool as a substrate. The final emergence percentage was higher than 95% and there was no positional difference within the row-tray or subirrigation bed with regard to plant height or leaf number of the tomato seedlings.

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The effect of the antioxidant compound 3-tert-butyl-4-hydroxyanisole (BHA) on the early growth of potato shoots cultured in vitro was examined. The growth of potato shoots at the early stage of cultivation was promoted by addition of low concentrations of BHA. Formation of lipid peroxide was inhibited by the addition of BHA. Although the activity of the antioxidative enzyme SOD was stimulated by the addition of low concentrations of BHA, peroxidase activity, which detoxifies H₂O₂, was inhibited by BHA depending on its concentrations.

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To improve the taste of leaf lettuce (Lacutuca sativa L.) grown hydroponically, an introduction of sweetening chemicals into the plant through the roots was examined. Sweetening chemicals used in this study were steviol glycosides obtained by extracting the leaves of Stevia rebaudiana Bertoni. Glucose molecules were partially combined with the steviol glycoside molecules by an enzymatic procedure with α-glucosyltransferase.
Stebioside and rebaudioside-A were more markedly accumulated in lettuce leaves than other steviol glycosides and their introduction ratios, the ratio of the amount of a steviol glycoside contained in the plant to the amount in the volume of solution absorbed by the plant, were 0.15-0.25 and 0.8-0.11, respectively. The steviol glycosides with combined glucoses were hardly incorporated into lettuce leaves. The lettuce leaves, when treated with the steviol glycoside solutions at the concentrations of 0.5% or 1.0%, were shown to be evidently sweet and tasty by the sensory evaluation test.

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A measurement system has been fabricated to investigate the bio-magnetic field of mushrooms using a SQUID (Superconducting QUantum Interference Device), which is characterized as having the highest known sensitivity to magnetism (in the order of fT). A novel non-contact and non-invasive measurement technique was established to trace the spontaneous magnetic field produced by a Grifora frondosa fruit body. Measurements were made of the minute photoexcited bio-magnetic field, induced by the switched photo stimulation. A magnetic field that varied with photo-stimulation was confirmed in five cases out of 60 experiments. These results verify the effectiveness of the use of SQUIDs in the measurement of the bio-magnetic field of mushrooms.

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