In the middle of the 1980's in China, "the optimal scale" problem was presented and became an important problem in agricultural economics. In this paper, Cobb-Douglas Production Function was used to examine a typical case in Haicheng city, Liaoning province, China. Based on the tillage area, 100 rice farmhouseholds were divided into five groups as follows: equal to or less than 100a, 101〜133a, 134〜166a, 167〜233a and equal to or more than 234a. As a result, the optimal scale is calculated to be 134〜360a according to the estimated production functions. The optimal scale of a rice farming was also affected by the labor number, power of the labor, technical level of the agricultural machines, and so on. In Haicheng city, the management scale was small, and only 16.2% of the farmhouseholds reached the optimal scale. It is suggested that the management scale should be enlarged to obtain the scale benefit for most of the rice farming in China as well as in Haicheng city.

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The regeneration of wasabi (Wasabia japonica Matsumura) in vitro was investigated by culturing leaf, stem, petiole and callus explants. Bud formation was induced in leaf, stem and callus explants cultured in MS medium containing kinetin or TDZ (n-phenyl-N'- 1, 2, 3- thidiazol-5-yl-urea or thidiazuron) with NAA(α-napthaleneacetic acid). Calli formed from all types of explant in a medium containing 1 or 2 mg /l of both BA (6-benzyladenine) and NAA. Stem and callus explants cultured on a medium containing BA and NAA showed bud-like formations but these failed to develop further, even at a high concentrations of BA and NAA or BA and 2, 4-D (2, 4-dichlorophenoxyacetic acid). But in several cases, an array of bud-like structures was observed. In one case (1 mg /l BA and 10 mg /l NAA), a leaf formed from a stem explant after about 6 months of culture. Root formation was observed in a few stem explants but not in callus explants when NAA and BA were present in the medium. In stem explants, buds formed and developed over a wide range of TDZ or kinetin concentrations in the presence of NAA. Both bud and root formation were most promoted in callus and stem explants at 0.002 or 0.02 mg /l TDZ with 1 or 2 mg /l NAA. Buds or roots were more abundant when TDZ rather than kinetin was used.

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The growth and yield of soybeans grown in an upland field converted from paddy field (CUL) were examined for three successive years after conversion. The growth and yield of soybeans grown in the ordinary upland field decreased year by year, but those in the CUL increased and decreased in the following order : the second year > the third year > the first year. Soil moisture content in the CUL was the highest in the first year. These results suggested that the growth and yield in the CUL in the first year was low due to the high soil moisture content, and low in the third year due to injury by continuous cropping.

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Enterobacter cloacae SM10, which is an endophytic bacterium with the potential to suppress Fusarium wilt of spinach, produces indole-3-acetic acid (IAA) via indole-3-pyruvic acid. The effects of IAA production on disease suppression were studied. The strain SM10R, a spontaneous rifarapicin-resistant mutant of SM10, was used as the parental strain. The IAA-deficient mutant SM10RK was constructed by marker exchange mutagenesis, which introduced the kanamycin-resistance gene into the indolepyruvate decarboxylase gene of SM10R. SM10R significantly suppressed the disease incidence and severity, whereas SM10RK did not reduce the disease symptoms. These results suggested that IAA production in SM10 was essential for the suppression of Fusarium wilt of spinach.

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In order to establish a reasonable utilization method of the waste of farm products, we discuss the characteristics of plowing-in sweet potato vine by rotary tilling. This paper reports the relationship between a tilling pitch and the quantity of plowing-in vine, the quantity of the exited vine at ground, the quantity of twined vine at rotary, the quantity of moved vine, the depth of plowing-in vine, and the length of cut vine, respectively. The results obtained are as follows. 1)The quantity of the plowing-in vine showed a tendency to decrease with the increase of tilling pitch for both raw and dry vine. 2)The quantity of plowing-in vine at each plowing depth showed a tendency to decrease with the increase of tilling pitch for both of them. 3)The quantity of plowing-in vine at each cutting length showed a tendency to increase with the increase of tilling pitch for raw vine, while the quantity showed a tendency to decrease with the increase of tilling pitch for dry vine.

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Six kinds of warm season vegetable crops, winter squash, bottle gourd, perilla, edible burdock, eggplant and tomato were grown in hydroponics for two to four weeks. The effects of solution temperature on their root and their shoot growth were investigated. The optimum solution temperatures for the root elongation of winter squash and bottle gourd (av. 22.9℃) were in the lowest range. Perilla (25.3℃) and edible burdock (25.5℃) were in the moderately high range of temperature. Eggplant (29.8℃) and tomato (30.5℃) were in the highest range of temperature. The root weight was also affected by the solution temperatures. The optimum temperature for root weight growth of edible burdock (18.1℃) was the lowest and eggplant (33.6℃) was the highest. Furthermore, the leaf area was affected by the solution temperatures. There were significant correlations between the leaf area and both the root dry weight and maximum root length.

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The Chugoku District has achieved great success in calve production, but beef cattle production itself has been hampered by a decrease in the number of farms and stagnation of their sizes. This paper examined the issues below, clarifying the direction to the development of beef cattle farming in the district: (1) the relationship between farming technologies, farm size, and land use; (2) the relationship between the less-used and abandoned lands, technology, and management; and (3) the trend of the multilateral function of land use for beef cattle production. Based on the above discussion, the paper pointed out various other issues to consider for the development of sustainable patterns of land use for beef cattle production in hilly and mountainous areas.

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This study was undertaken to clarify the effect of fertilizer application, topping and shading on the shoot length and flower-bud formation.1. Taking root ratio of cutting Percentage of taking root was high, regardless of type or cultivar in both hardwood and softwood cutting. 2. Effects of fertilizer level and application time In both treatments of basal fertilizer and side dressing one, the flower-bud formation also increased with the increase in fertilizer level. The number of flower buds of the rooted cutting in hardwood was more than that in softwood cutting, and 'Tifblue' was more abundant than that of the 'Northland'. The flower-bud number was also the most abundant on both cultivars in the side dressing fertilizer in August. 3. Effects of topping and shading Heavy topping decreased spring shoot length, but did not affect the number of flower buds. In both cultivars Woodard and 'Northland', the effect of the shading of the flower-bud number was bigger than that of the spring shoot length, and the number of flower buds remarkably decreased, when the shading rate increased. As the results of the cultivar comparative experiment, Rabbiteye blueberry 'Woodard' is suitable for pot culture plants, because many flower buds and branch are abundant, and it spreads to the width and low height.

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The spatial variation of rice productivity in a large paddy field (58 × 30m) made by merging 3 small terraced fields in 1964, was investigated. The small fields were merged by moving a large amount of top soil from the highest latitude of terraced field toward the lowest one. Yield, total soil nitrogen and carbon concentrations in the deep soil layer tended to increase with descending relative latitude of terraced fields before merging. Spatial variation of yield was smallest in the site which had been at the lowest latitude in the terraced field. These results indicated that rice productivity at each place in a field is strongly affected by the merging of fields even after 36 years had passed.

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The drying methods of paddy dryers had shifted from a bed type to a circulation type, and now its mainstream is on the intermittent drying method using the tempering period. To improve the performance of paddy dryers maintaining the quality of rice, it is important to understand the moisture transportation process between the husk and brown rice and apply this knowledge to the development of new paddy dryers. In this study, various drying characteristics were examined by using test equipment and then the drying performance was confirmed with a prototype dryer. The test results cleared the methods of improvement in paddy drying speed and energy saving.

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In this paper, a visualized and dynamically displayed method of AMeDAS data is applied to weather analysis in the Hokuriku District, namely Toyama, Ishikawa and Fukui Prefectures. In these three prefectures, there are 29 measurement points when measuring the four meteorological elements (air temperature, wind direction-wind speed, sunshine duration and precipitation). In order to clarify the relationship of the weather and geographical features more precisely 50m and 250m-mesh digital map data of the Geographical Survey Institute of the Ministry Construction were used to display the background. Therefore, the possible sunshine durations in this district were calculated from the declination angles of the sun and by the longitude and latitude using sunrise and sunset time data of the National Astronomical Observatory(Tokyo). The other details are almost analogous to the report of Part 2. From this analysis, the relationship of meteorological elements and hourly behavior of the weather phenomena become visually evident. However, it was found that an actual sunshine duration was very dependent not so much on possible sunshine duration, but on natural features and the quantity of clouds obscuring these areas.

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The resarch is about how the production of the first crop of tea plants in the next season influenced the pruning after the second crop and the varied skiffing time in the tea bush, where the third crop was not plucked. The area of IKAWA is a cool climate district of the Shizuoka prefecture. The autumn skiffing (in middle October) tended to be the bud number type and the spring skiffing (in late March) tended to be the bud weight type. The sprouting rate of the autumn skiffing was higher than one of the spring skiffing. Although the harvest time of the spring skiffing was delayed, it had a high production rate. The combination of a common skiffing and an autumn skiffing resulted in a low production rate. The autumn skiffing had a better growth uniformity of new shoots on the canopy surface. In the case of the act of light or hard pruning, the autumn skiffing was proper because the reseach focused on the number of buds the most. It was considerd that the proper combination of pruning after the second crop and the time of skiffing could be selected according to the level of late frost in the area.

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