Fresh weight at the harvest of lettuce plants (Lactuca saliva L. cv. Red-fire-W) grown in a plant factory with fluorescent lamps was estimated by the automatic plant growth measurement system with a personal computer. Growth curves of leaf area, fresh- and dryweight of above ground parts from sowing to about 30 days in age showed an exponential pattern (r²=0.90 or higher) . It is most suitable to use an exponential regression function during young stage of the growth, considering a declining pattern in specific growth rate. Standard deviations at 6.1-5.4 were observed between the top fresh weight in 30 days after sowing and specific growth rate revealed by the regression curve of leaf area. On the other hand, standard deviations obtained by the leaf area estimated from the regression curve were 6.4-3.9. Further, standard deviations were 3.6-3.1, where the initial leaf area and specific growth rate were regarded as describing parameter. The growth of lettuce plant was quantitatively represented as the function of leaf area by image processing. Specific growth rate of leaf area of individual plants in young stage of the growth showed periodic fluctuation. As the plant grew from sowing, its cyclic period became longer. The leafing velocity is defined as a cyclic period of changes in specific growth rate.

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Growth parameters of spinaches (Spinacia oleracea L.) grown inside and outside of spunbonded polypropylene rowcovers were calculated and compared each other to understand characteristics of plant growth under rowcovers made of poromeric materials. Plants were covered when two leaves unfolded in March. Solar radiation under the rowcover was about 85% of that outside the cover. The rowcover increased mean daily maximum air temperature and mean daily minimum soil temperature by 1.7°C and 0.6°C, respectively.
The rowcover enhanced plant growth. Increase in dry matter production rate per unit of dry matter (RGR) under the rowcover brought the rapid growth of covered plants. Larger RGR under the rowcover was due to the increase in dry matter production rate per unit leaf area (NAR) at early growth stage and the increase in leaf area per unit dry matter (LAR) at subsequent stage. Leaf area per unit leaf dry matter (SLA) was affected by the rowcover more than ratio in dry matter of leaf and plant (LWR) . The primary factor of LAR under the rowcover was the increased SLA.

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Pink-pigmented facultatively methylotrophic bacteria (PPFMs) were isolated from fourteen kinds of phylloplanes in Pinus densiflora forest. PPFMs were Gram-negative, lophotrichously flagellated rods and attacked glucose fermentatively. All pink isolates utilized methanol, methylamine and formic acid as the sole carbon source but did not utilize methane. The PPFMs belonged to the genus Methylobacterium. The methylobacteria were found on the every phylloplane of the plants in P. densiflora forest. The fluctuation pattern in population of Methylobacterium was summerized as follows : (1) On the living leaves of Pinus densiflora, Methylobacterium occurred abundantly during summer although the number decreased abruptly in winter. The airborne methylobacteria behaved in the similar way as on the pine phylloplane. (2) On the phylloplanes of Cryptomeria japonica, Juniperus rigida and Ilex pedunculosa, these bacteria occurred even in winter. (3) Methylobacterium disappeared during the period from November to January on the leaves of Chamaecyparis obtusa and Eurya japonica. (4) Through the year round, higher occurrence of Methylobacterium was observed on the each phylloplane of the deciduous trees (Rhododendron macrosepalum, R. reticulatum, Lyonia elliptica, Quercus serrata, Rhus sylvestris, Vaccinium hirtum and Evodiopanax innovans) . These results indicate that Methylobacterium may reside favorably on the leaves of such plants as if it was epiphytic.

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For enhance the germination and the early growth of seed, carrot seed was stirred in distilled water to absorb water, and then was treated under the conditions of high electric fields as follows : the three kinds of alternative current field generated with a neon transformer; the positive and negative direct current fields generated with a high voltage rectifier, which had the two electric field intensities of 25 and 250 kV/m; and the two treatment times of 5 min and 1 hr.
The germination percentage and the germination rate of the moist seeds treated with high electric fields were increased than those of control, however, at all electric fields, the mean days of germination was increased except the high electric field of alternative current. At any electric field, the early growths of the treated seeds were progressed particularly at the root than that of control, the two treatments with the electric fields of the negative direct current and the alternative current were very effective for the early growth.
Hereafter, the more effective methods to improve the early growth must be inquired, and the action mechanisms in seed should be investigated.

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The calli of asparagus and carrot in a petri dish were exposed to positive and negative uniform electric field intensities of about ± 150 kV/m. The variance of the field intensity in a petri dish and the effect of the exposure for 20 days on the multiplication of callus were evaluated under the exposed conditions as follows : the continuous exposure (continuation plot), the repeat of pause of 4 hr after exposure of 8 hr (8-4 plot), the repeat of pause of 1 hr after exposure of 2 hr (2-1 plot) and the repeat of pause of 2 hr after exposure of 1 hr (1-2 plot) .
Generally, the petri dish is slightly charged to negative even under no electric field, and the field intensity in the plastic petri dish was smaller than that of the outside and grad-ually decreased, then was kept a constant value under the uniform field. The absolute value of the positive field intensity in a petri dish was smaller than that at negative, and the measured value of the positive field intensity was smaller than its theoretical value, the other way, the negative measured value was larger than the theoretical value. The accumulated exposed time was longer, the more the multiplication of callus was accelerated; and the periodic time of intermittent was longer, the more the multiplication was accelerated, but the short period suppressed the multiplication.
Both calli felt the different influence by the polarity, the intensity, the exposed time and the intermittent period of field. The multiplication rate of asparagus callus was most accelerated at the positive 8-4 plot and the negative continuation plot, and the dry weight and the dry matter rate were increased at the continuation plots of both polarities. In the case of carrot callus, the multiplication rate was most increased at the positive 2-1 plot and the negative continuation plot, and the dry weight and the dry matter rate were most increased at the negative continuation plot.

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This study was carried out to investigate the effects of grafting of melon scions (Cucumis melo L. cv. ‘Prince’) on squash root stocks (Cucurbita maxima × C. moschata cv. ‘Shintosa No. 1’) while fertilizers containing calcium were applied in soil in vinyl plastic greenhouses where the plants were grown.
The grafted melon plants grew more vigorously and bore larger fruits than the non-grafted melon plants. However, the quantity of soluble solids decreased significantly in fruits of the grafted melon plants, and further, the flesh color and aroma of the fruits were worse than those of the non-grafted melon plants. Fermentation of fruits of the grafted melon plants occurred more quickly than in fruits of the non-grafted melon plants. Thus, the quality of harvested fruits was better in the non-grafted melon plants than in the grafted melon plants.
The grafting treatment influenced mineral contents and fruit quality. In grafted melon plants, contents of nitrogen, potassium and carbon increased significantly in fruits, and the potassium content increased in leaves. The calcium content in fruits was lower in grafted melon plants compared with non-grafted melon plants. The quantity of calcium content in fruits was inversely correlated with the quantity of potassium contents in leaves. It was observed that fermentation of fruits occurred earlier and more rapidly when the calcium contents in fruits became lower. It is commonly believed that increasing the calcium content in fruits may delay fermentation. However, the application of calcium-containing fertilizers to the soil in greenhouses was not effective in increasing the calcium content of fruits.

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Knowledge on relationship between the rate of root respiration and dissolved oxygen (DO) concentration is essential for understanding the oxygen balance around roots in hydroponics. An airtight hydroponic system for the measurement of root respiration of lettuce was constructed. The initial concentrations of DO were 26 μmol⋅liter^-1 (“treatment one-tenth”), 130 μmol⋅liter^-1 (“treatment one-half”), 260 μmol⋅liter^-1 (“treatment saturation”), and 380 μmol⋅liter^-1 (“treatment over-saturation”) . From the patterns of decreasing DO concentration during a 48 hr measurement period, the minimum DO concentration for root respiration and the rate of root respiration were calculated. The minimum DO concentration for the root respiration of lettuce 26 days after transplanting was around 78.2 μmol⋅liter^-1. The changes of DO concentration in treatments with plants four and ten days after transplanting were small.
The rate of root respiration was presented as a function of DO concentration, and increased as the DO concentration of nutrient solution increased. For DO concentrations in the range from 190 to 230 μmol⋅liter^-1 which is usually observed in well aerated hydroponic beds, the rate of root respiration of lettuce 26 days after transplanting ranged from 2.9 to 6.7 μmol⋅hr^-1⋅ (ml roots) ^-1 at 23°C. In “treatment saturation, ” and larger root growth and greater amount of transpiration were attained in this treatment than in other treatments.

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