The objective of this study was to clarify the influence of dissolved oxygen (DO value) on the growth of plants to control the DO value with an aeration nozzle in solution cultuse systems. Tomato seedlings were grown in different DO value conditions in a range of 15〜45%(1.2〜3.8ppm). Changes in the fresh weight of the plant, stem diameter, the leaf area and the transpiration rate (water flux of the plant) were measured with various instruments, including a laser beam type displacement sensor, a heat balance sensor and a color video camera. From the experimental results, it was clear that under the same environmental conditions, a higher DO value content in the solution would result in a faster transpiration rate thus producing quicker growth, although a value rate below 15% would stop the plants growth. Consequently, it show that the growth of a plant could be controlled by the density of the DO value.

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The early or late flower-bud differentiation was caused by lines and cultivars. In the case of the highbush blueberry, the flower-bud initiationin in 'Northland' and 'Rancocas' began from the first ten days of June, and the pistil was recognized on the first or middle ten days of July. The varietal difference of flower-bud initiation was also recognized in the rabbiteye blueberry. The beginning of flower-bud formation in 'Woodard' was the first ten days of August, and the formation of the pistil was recognized in the first ten days of October. The longer the duration of cold storage, the shorter the periods from the start of forcing to sprouting and flowering were. The flowering had finished within the last ten days of December in all plots. From these results, branches of blueberry are able to be forced by about 40 or 50 days chilling from the middle or last ten days of October, and the ability of forcing the pot flower was indicated.

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The work efficiency of 'Fuji' apple trees on 'Marubakaido' rootstock with M.26 interstock trained to a Y-trellis system was compared with that trained to a central leader. 1.The bud and fruit number in the Y-trellis were greater than those of the central leader. In particular, the yield of Y-trellis was 6.2t/10a, 1.3 times as much as the central leader. 2.The annual working hours in the Y-trellis were 445.6 hours, 1.2 times as long as the central leader. However, the annual working hours per yield in the Y-trellis was 10% shorter than that of the central leader, and the productivity of labor per yield in the Y-trellis was superior to that of the central leader. 3.The conventional work which required a special technique was 96 % of all working hours. 4.The pollination, fruit thinning and harvest time per yield in the Y-trellis was shorter than that of the central leader.

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The object of this paper is to analyze farm works and farm work hours in a diversified paddy farm at "Farmer S" at HIKAWA town in SHIMANE prefecture. The major results of the analysis are as follows: 1) The diversified farming system develops along with certain links of improvement of land conditions, improvement of labor means, and change of the farm organization. Then, the quality and quantity of the family labor force decides the farms organization. 2) The farm work of each section, which consists of diversified farms, is made up from Fixed and Non-Fixed work, and Machinery and Non-Machinery work. All farm work must be combined properly in order to establish diversified farming. For the sake of this, the efficient use of the family labor force and the cooperative works among family labor forces are needed.

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The objective of this study is to find out the relationship between the thermal conductivity of biomass compressed solid beds which are made with bark materials of Japanese cedar and cypress, and the factors (the volumetric water contents, the size of bark fibers and the apparent density of bed materials). The thermal conductivity slightly increased with the increase of temperature, and in the apparent density, it's vice versa, and is almost unaffected by the size of bark fiber, and in the volumetric water content it is apparently constant in the range of 0.12〜0.23[W/(m・K)].

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It is necessary to measure the growth progress of young vegetables. The image processing and laser sensor are effective methods for intact and non-destructive measurement. This study was undertaken to establish the automatic selection system by image processing and laser sensor, and use it to measure the characteristic indices of tomato seedlings. The possibility of automatic sorting was discussed by measuring the characteristic indices. In this research, extracting a seedling image based on chromaticity in the color image of the seedling was tested. The indices of property, such as the size and shape of seedlings were measured by the horizontal and vertical projection. The relationship between each index of property and top fresh weight was inspected. The results indicate that there are linear relations between the leaf area, stem diameter and top fresh weight. And the ratio of seedlings height to width is relative to area of the seedlings vertical projection. They are important factors to evaluate the quality of tomato seedlings.

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The effects of paclobutrazol (PBZ) to sweet cherry cv. Satohnishiki on net photosynthesis and mineral element concentration of leaves, and also of foliar sprays at different stages of shoot growth on vegetative growth and fruit quality were investigated. 1. Application of 215 ppm PBZ on whole trees was performed 24 days after full bloom (DAFB) (during shoot elongation) and 78 DAFB (after shoot growth suppression). Shoot growth, measured the following year, decreased by both PBZ applications. Most notable was the average and total shoot growth of the 78 DAFB treatment which was about 43% and 5% of those in the untreated control, respectively. In contrast, the number of floral buds per unit crown volume, and the fruit yield per trunk cross-sectional area increased as a result of the PBZ treatments. 2. PBZ treatment increased the photosynthetic rates per unit leaf area, under both direct sunlight and scattered light conditions, as well as nitrogen, calcium and magnesium concentrations in the leaves. Although the leaf area of the PBZ-treated trees decreased to 69-77% of that in untreated control, the dry matter percentage of the treated leaves increased. 3. Individual fruit weights significantly increased as a result of PBZ treatments. The number of leaves per fruit was reduced by PBZ treatment because of the increase in fruit set. However, the percentage of soluble solids in extracted juice was not reduced in fruit from the PBZ-treated tree compared to the untreated control. These results may be related to the inhibition of vegetative growth, and the increase in mineral element concentrations and the photosynthetic rate. In addition, the percentage of coloring area and the anthocyanin concentration of the peel increased as a result of PBZ treatment, suggesting that the amount of light transmitted into the interior portion of the canopy increased as a result of the decreased shoot length.

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The analytic method and measurement system for the static muscular work has been investigated. The static muscular work is frequently done in farm work connected with horticultural production. It is known to have the characteristic of low energy metabolic rate and high muscle fatigue at the specific muscle keeping the work posture. So, the static muscular work could not be estimated by R. M. R. or the heart rate. Therefore, this measurement system consisted mainly of the telemetry polygraph, and the signal processor was used for the average muscular electric action potential(AMEP) that is calculated from the electromyogram. It was clear that AMEP correlated with muscle strength. The characteristic of the working posture and motion can be understood by this analytic method. The result of the experiment to be applied to this method in lettuce packing work, the reduction effect of the work intensity by the improvement of the work posture was cleared by AMEP.

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A 3-D vision sensor which scanned the crop surface was made by trial and experimentation for an agricultural robot. The sensor emitted red and infrared light beams into the same optical axis from two laser diodes. The reflected light from the crop surface was detected by a PSD (Position Sensitive Device), and the distance to the crop surface was calculated by way of a triangulation. The 3-D shape of the crop was measured by scannning the laser beam in vertical and horizontal directions. The red and infrared components of the detected voltage of the PSD were also measured. It was able to distinguish the red ripe tomatoes from leaves by comparing these two voltage components. The time required to scan one flame (60 × 60 pixels) was 3 seconds. The harvesting experiment of tomato fruits was done using the sensor.

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