Brassinolide was first discovered from the pollen of rape (Brassica napus L.) in 1979 ; since then it has been found from more than 20 species of plants. And many researches have been done including its practical utilization in agriculture. The purpose of this report is to clarify the uptake, translocation and transformation of brassinolide in rice plant seedling using ^3H-labeled brassinolide. Plant materials were fractionated by chloroform and water, and separated by the thinlayer and high-performance liquid chromatography. The following results were obtained. (1) Foliar uptake of brassinolide was much lower than that of root uptake. (2) Most of brassinolide which has been absorbed from roots was transported without being metabolized in roots, and translocated to the shoot by xylem transpiration stream. (3) A part of brassinolide was transformed to water-soluble metabolites in roots and translocated to the shoot. (4) These water-soluble metabolites did not show physiological activity of brassinolide by rice lamina inclimation bioassay.

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Rhizobium-inoculated common bean was cultivated with basal application of 20 mg nitrogen as the form of ^<15>N-ammonium sulfate in small pot containing artificial vermiculite. Nitrogen uptake and distribution, root nodulation, acetylene reduction activity(ARA) and soluble sugar concentration (SSC) in roots and nodules of the plants were compared after 26 and 42 days of sowing with those of soybean cultured by the same manner. Smaller plant body and shoot/root ratio, much larger nodule number and nodule weight, and earlier uptake of dressed nitrogen characterized common bean in comparison with soybean. Much higher ARA per plant and per nodule weight were detected in common bean at the both stages, thought they were sharply declined in the 42-day-old plants. Also ARA per nodule weight of soybean diminished at the second measurement, but ARA per plant rose in contrast with the case of common bean. In both plant species, SSC based on dry matter was higher in nodules than in roots. And, SSC in nodules of common bean was higher than that of soybean at the 26th day. But the relationship between the two species nodules was reversed at the 42nd day due to that the concentrations were respectively reduced and increased in common bean and soybean nodules, suggesting that the rapid decline of ARA in common bean was related to carbohydrate shortage in nodules. At the 42nd day, apparently three kinds of nodules were observed on the roots of common bean ; these were large red, middle blue and small pink nodules. Although pink one was dominant in number, the red shared more than 70% of total nodule dry weight. SSC was the highest in blue inactive nodules and the lowest in active red nodules, and which may reflect the activity of sugar consumption for nitrogen fixation and assimilation of its product in nodules.

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The effects of chemical form of Zn and Mn added to the soil on the behavior of micronutrient elements around the wheat roots were investigated using the rhizobox system. Mn and Zn were added either as water-soluble form (MnCl_2 and ZnSO_4) or citrate-soluble form (fritted Mn and Zn). Wheat seedlings were grown in the central compartment of the rhizobox. After 40 days of cultivation, all the compartments were separated from the rhizobox and the soil from each compartment was dried and served for the analysis of the element composition. The plants were simultaneously harvested and the contents of the elements were analyzed. The results obtained were as follows : 1) Changes in pH in rhizosphere due to plant cultivation were observed in all the treatments and similar trends in pH change were observed whether the pH was measured in water or in 1 N KCl suspension. The pH values along the rhizosphere of wheat roots decreased by about 1. 1-1.2. The significant decrease in pH by the wheat roots was observed in the area 3-4 mm from the central compartment. The chemical forms of Mn and Zn added to the soil did not influence the pH of the soil so much. 2) Total content of each element (Cu, Zn, Mn, Fe or Mg) showed little or no difference among the compartments, but that of Ca increased slightly in the central compartment. Concentrations of DTPA-soluble Zn and Mn were much higher when these metals were added as water-soluble form than citrate-soluble one. 3) Soluble Zn decreased while other soluble heavy metals (Mn, Fe and Cu) increased near the root in the treatment of zinc sulfate or with the mixture zinc sulfate and manganese chloride. On the other hand, the application of citrate-soluble Ca decreased near the root by the application of citrate-solble Zn and Mn. Soluble K decreased toward the root zone in every treatment, but increased again in the central compartment only by the treatment of citrate-soluble Zn. 5) Distribution of elements in the wheat plant was studied. The concentration of Zn of roots had intimate relations to that of DTPA-soluble Zn of the soil of R. C. of each treatment. When citrate-soluble Zn was added to the soil, the rations of Zn concentration of the top to that of the root were generally higher than those when water-soluble Zn was added. For other elements, no significant influences due to the difference of chemical form of Zn and Mn were observed.

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The calcium carbonate and calcium sulfate were applied to tea field and the effects on nitrifying activity in the soil, the growth of tea plant and nitrogen contents of new shoots were investigated. The leaf yield was greatest in the field where any calcium material was not supplied. And it decreased in application of calcium carbonate as increasing the amount. The yield in calcium sulfate was smaller than in the non-application. But the differences were not recognized in the fields where calcium sulfate was supplied at different amount. Amount of total nitrogen and amino acid contents in new shoots decreased in the both application of calcium carbonate or calcium sulfate as increasing the amount of application. The nitrifying activity and pH of soil were higher in the field where a large amount of calcium carbonate was supplied, while the effects of calcium sulfate were small. Thus, the rate of total nitrogen and amino acid contents in new shoots were deteriorated and the plant growth was inhibited by application of calcium source. It is suggested that this deterioration is due to two factors ; one is high pH promoting nitrifying and another is large amount of calcium which acts antagonistically on nitrogen absorption. It is considered that these factors caused reduction of nitrogen absorption.

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The magnetization rate to the paddy soils and their neighboring upland soils distributed in the northeast of China was measured by the WCL-1 type magnetization rate measure meter, and the correlation between the magnetization rate and the physico-chemical properties of these soils was studied. Its significance to soil formation process of paddy soils in the northeast of China was also discussed in this paper. The results showed that magnetic rate of polowed layer of paddy soils was evidently lower than that of the neighboring upland soils. The higher the magnetic rate of the original soils, the more the magnetic rate decrease after rice cultivation. And for those derived from the same original soils, the longer the period of rice cultivation, the bigger the magnetic rate drops. Moreover, magnetic rate of paddy soil was correlated negatively with the content of clay (<0.002 mm) but positively with the content of organic matter, the free humic acid fHa, PQ_1 value and organic complex Fe level.

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In this report, a detailed soil map was prepared using correlation of microtopography with soil distribution. And then the lacking soil data of fields were supplied with the Soil Information System (SIS) and the accuracy of these supplied soil data were checked with actual soil survey. Additionally, the practical soil map was prepared by using both the detailed soil map and SIS. It was found that there is a good correlation between microtopography and soil type distribution as follows : Brown Lowland Soils (Typic Udifluvents) and the natural levee in lowland ; Pseudogleys (Typic Haplaquepts) and plateau of convex microtopography in terrace ; and Gley Upland Soils (Humic Haplaquepts) and the concave microtopography in terrace. In the old river channel, however, Gley Lowland Soils (Typic Haplaquepts) or Gray Lowland Soils (Fluventic Haplaquepts) distributed with different texture class such as fine or gravel. In backmarsh, soil types were transited gradually to Gray Lowland Soils, Gley Lowland Soils and Lowmoor Peat Soils (Medihemists) in accordance with hydromorphic condition. Therefore, it is necessary to identify soil types and determine the border of soil phases with the actual performance of soil survey in old river channel and backmarsh. The error for the depth of gravel layer and gley layer between from the actual soil survey and from interpolated SIS and the detailed map, was 27% in maximum. The causes of error are due to the accuracy and mapping unit of detailed soil map. These errors may decrease with increasing soil survey data that can be input to SIS. It was concluded that the practical soil map for management of field soils can be prepared rapidly and effectively using the detailed map and SIS.

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Soil nutrients status and rice yield components were compared among experimental fields with various duration of upland or lowland conditions. The soil type was Gray Lowland Soil with good drainage. 1)The rotation of upland and paddy crop was effective to increase available soil nutrients such as nitrogen, phosphorus or silica. It was found that short-term rotation, e.g. 2 to 3 year planting on upland field and 2 to 3 year planting on paddy field was more appropriate than other rotation system, e.g. longer-term rotation or annually alternative rotation. This conclusion can be supported by the relationship between changes in soil nutrients and "soil in the process of drying index". 2) Short-term rotation is an effective soil management for maintaining stable and high yield of paddy rice. In well-drained Gray Lowland Soil, short-term rotation is appropriate for maintaining stable soil productively.

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The soil percolating water from sugi (Cryptomeria japonica D. Don), hinoki (Chameaesiparis obtusa S. et Z.) and broadleaf stands was collected and analyzed throughout two years. The results obtained were as follows. 1) The pH of the percolating water was 4 to 5 except a 165-year-old stand, and lower than the soil pH(H_2O), but seasonal variation was observed. The pH of the surface horizon was lower by 0.3 to 0.5 than that of the subsoil. 2) In the sugi and the hinoki stands, nitrate ion comprises 60 to 70% of the total anion in the percolating water. This suggests that nitrate ion liberated by the mineralization of organic nitrogen controlled the salt concentration of the soil percolating water. Nitrate ion concentration in the broadleaf stand was one-several decades of that in the conifer stand. 3) The calcium occupied more than 60% of the total cations of the soil percolating water in the sugi stand and about 40% in the hinoki stand, whereas magnesium, potassium and sodium were about 20% respectively in both stands. 4) The cation and anion concentration in the percolating water increased with the increasing age of sugi stands from a young to an established stand. 5) The main ion pairs in the percolating water was considered as calcium nitrate in the sugi and the hinoki stands, but sodium chloride in the broadleaf stand.

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We investigated Ando soils under the Miscanthus sinensis grassland, the adjacent successional red pine (Pinus densiflora) forest and the successional deciduous broad-leveled forest dominated by Quercus mongolica var. grossererrata at Sugadaira, Central Japan. And we examined the effects of secondary succession on the physical and chemical properties of Ando soils. F-H layer developed and hardness of surface soil decreased with succession. The bulk density of soil decreased and the porosity and hydraulic conductivity of soil increased with succession, content and DBC-extractable Fe_2O_3, DCB-extractable Al_2O_3 and phosphate retention. Organic carbon content and CEC of surface soils decreased with secondary succession.

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Humus characteristics of Ando soils during secondary succession were studied at Sugadaira, Central Japan. 1) The values of color density (CD) of NaOH extractable humus decreased, and the Δlog K values increased during secondary succession. 2) The amounts of humic acid fractions in the Miscanthus sinensis grassland soils were greater than those in the red pine forest soils. 3) The Δlog K values of humic acid fractions ranged from 0.52 to 0.56. And the RF values of humic acid fraction in the lower parts of A horizons were higher than those in the upper parts. 4) The RF values of humic acid fractions decreased during the secondary succession. It seemed that the decrease of the RF values related to the pedogenesis of degraded black soils.

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We observed micromorphology of Ando soils under the Miscanthus sinensis grassland, the red pine forest and the successional deciduous broad-leaved forest at Sugadaira, Central Japan. And we examined the effects of secondary succession on soil micromorphology. 1) The microstructure of surface soil changed from subangular blocky to crumb structure during the succession. 2) There were numerous granules of soil mesofauna excrements in the secondary forest soils. 3) The fractal dimension on distribution of peds increased with succession from 1.346 to 1.406. This indicates the increase of the surface area of the peds.

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