Leaching of several components from soils with percolating water was measured by a column experiment during 150 days of incubation under controlled conditions. In this experiment, four kinds of agricultural soils in Japan (Andosol, Brown Forest soil, Gray Lowland soil, and Dark Red soil) and two kinds of composts (sewage sludge compost and city refuse compost) were examined. The results are as follows ; 1) pH values of percolating water measured during incubated periods from soils applied with city refuse compost were high compared with those applied with sewage sludge compost and the control. Percolating water high compared with those applied with sewage sludge compost and the control. Percolating water from Dark Red soil applied with city refuse compost and sewage sludge compost showed a pH of about 8 during the whole period of incubation. On Andosol, Brown Forest soil, and Gray Lowland soil with compost applied, pH percolating water was depressed at an early stage of incubation. 2) Electrical conductivity (EC) of percolating water during incubation showed the order : city refuse compost > sewage sludge compost > control. EC of percolating water from soils applied with city refuse compost showed maximum values during 20-30 days of incubation due to leaching of cations. In the case of soils with sewage sludge compost, the maximum values of EC were shown during 30-50 days of incubation by leaching of nitrate nitrogen. 3) Concentration on nitrate nitrogen in percolating water from soils applied with sewage sludge compost and the control were markedly high compared with city refuse compost ; however, on soil with city refuse compost applied, concentration of nitrate nitrogen was high. 4) Concentration of cations and anions in percolating water differed according to soils and composts. From these discrepancies in ion balance it was estimated that the leaching of anions such as phosphoric, carbonic, and organic acid had occurred. 5) It was concluded that leaching of several components from soils applied with city refuse compost occurred at an early stage of incubation whereas that from soils applied with sewage sludge compost continued to occur throughout the period of incubation.

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A series of experiments were conducted to ascertain the accuracy of D/H determination by applying a TCD-gas chromatography and to improve the methods of sample preparation for the determination. The sensitivity, repeatability, and reproducibility of D/H determination by the TCD-gas chromatography was significantly improved when low D/H hydrogen (LDH), which is supplied from a hydrogen generator fed by water of low deuterium content, was used as the carrier gas . The calibration curve was fitted very well by a straight line in the range of D/H from 100 to 1000 ppm and the least significant difference at confidence level of 0.05 was less than 3 ppm and 8 ppm in the cases of more than 40 and 5 replications, respectively. The reproducibility of D/H determination was also satisfactory, especially in the cases of low D/H samples near natural abundance. When commercial high-quality hydrogen was used as the carrier gas, the linearity of the calibration curve was satisfactory, but both repeatability and reproducibility were somewhat inferior compared with those obtained by using LDH. In the direct distillation of soil samples to prepare water sample for the analysis, the efficiency of vacuum distillation apparatuses, which were proposed previously, was not satisfactory. The efficiency was improved significantly by using a larger distillation flask of more than 30 mm in inner diameter and the accuracy of determination was not influenced by the alteration. A tension lysimeter system was devised and tested to extract soil solution in the field experiments. It was concluded that the system was suitable when the soil water suction was less than about 0.3 bar. The isotope effect together with the extraction was not so significant, but some correction was recommended to compensate the reduction of D/H caused by the isotope effect. In field experiments, tracer solution is diluted rapidly by soil water. The determinations, therefore, have to be performed in the low range of D/H from natural abundance to about 300 ppm and, moreover, high reproducibility is required to evaluate the time series of D/H change in soils. The reduction of background by using LDH as the carrier gas and frequent calibration (two standard samples for a lot of determinations) were recommended to maintain a satisfactory accuracy and reproducibility.

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To obtain basic information on the natural abundance of deuterium water, water samples in Hokkaido were collected and analyzed. The average and range of δ_D values of rain (snow) water samples in the suburbs of Sapporo were -60.6 and -140~1.5‰, and the daily fluctuation seemed to be significant. The values of coastal sea waters around Hokkaido were slightly lower than those of the standard sea water (-20~-10‰) ; especially in Ishikari Bay, the natural abundance of deuterium water was lower than that of other coastal regions. This may be attributable to the isotope dilution by big-river water. The δ_D values of big-river waters, e.g. Ishikari River, were in the range from -95~-75‰, and their variation was not remarkable. The low, consistent δ_D values of big-river waters would be due to the dilution by discharges form inland tributaries. The natural abundance of deuterium water in lake waters and related river waters, e.g. Lake Shikotu and Chitose River, were higher compared with those of the big-river waters. This is probably caused by the sampling strategy of the present study. Small tributaries and lakes in inland areas should be included to obtain limnologically unbiased results. The natural abundance of deuterium water in the greater numbers of soil samples was -116.3‰ in average and its variation was in the range of -150~-60‰. In general, both the average and the range of the natural abundance were greater in surface soils than those in subsurface soils and the values of subsurface soils were around -120‰. The influence of D supply by preceding rains was usually held in the profiles of δ_D values in soils and the behavior of water in soils could be studied by tracing their change with time. Some correction on the amount of deuterium water that is supplied by rains in the duration of the experiments is indispensable, especially in the long-term field experiments. This means that the determination of D/H has to be performed in a low D/H range near the natural abundance. Precise analysis managements, therefore, are required to perform this by using TCD-gas chromatography. Frequent calibrations together with the reduction of background by using low D/H hydrogen carrier gas are recommended to maintain high accuracy and good reproducibility of the laboratory analysis as described previously.

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The mechanisms of growth suppression of rice plants by high concentrations of NaCl were examined by means of the detachment of roots, the addition of metabolic inhibitors, and the equalization of osmotic pressure in culture solution, and by then making a comparison between Na absorption of excised roots and whole plants. The results obtained are summarized as follows : 1) The varietal differences of salt tolerance among rice plants were caused by the differences from the response of ion injury in plants rather than of high osmotic pressure in medium at least at about 160 mOsmol/kg in culture solution. 2) The varietal differences of Na accumulation in the shoot were attributed to two processes such as Na-holding ability and Na-excluding power of their roots. But both might not be independent processes, and it was suggested that they were physiologically connected with each other. 3) If the rice plants were grown in culture solution supplied with the high Na of 80 mM, the susceptible varieties that had lower Na-holding ability of their roots immediately showed decreased ATPase activity in their roots, so that Na accumulations in their shoots were accelerated more rapidly than in tolerant varieties.

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Wild turf Sporobolus virginicus, a salt-tolerant plant, is commonly grown on the seashore and the sandbanks of coastal rivers in the south-west islands of Japan. The mechanism of salt tolerance of S. virginicus was investigated by comparison of mineral composition of autogenous plants and salt-treated ones grown by water culture technique, and by anatomical experiment of its leaf. The results obtained are as follows : 1) S. virginicus grew favorably on the seashore that contained a high concentration of NaCl in the soil and submerged water, but Na content in tissue was relatively low. 2) The growth of S. virginicus cultured with the nutrient solution of 0.03 and 0.1% NaCl exceeded that of the control, and the yield of S. virginicus corresponded to 70% of the control even in 1.0% NaCl condition. The rise of Na content in its tissue with increase of Na in media was minimal. Na content in the top of 1.0 and 3.0% NaCl-treated plants was lower than that in the root. This suggests that S. virginicus has a suppressive function to Na uptake and Na transport, from root to top. 3) Salt crystals were found on the leaf surface of S. virginicus grown in salt-treated solution. Analytical observation of leaves showed that S. virginicus has salt glands on the adaxial surface. 4) There results suggest that S. virginicus could maintain a salt concentration at a lower level in the tissue against the external saline condition by a suppressive function to salt uptake and the salt exclusion through salt glands of the leaves.

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1)Effect of nitrogen, phosphorus, and manganese deficiencies on the formation of anthocyanin and other phenolic compounds were investigated with seedings of two cultivars of corn (Zea mays L.), Yellow Dent (YD), rich in anthocyanin, and Golden Crossbantam (GC), poor in anthocyanin. The nitrogen deficiency increased the contents of total phenol and flavanol in the leaves of both YD and GC more remarkably than the phosphorus deficiency. For YD, phosphorus deficiency caused a drastic accumulation of anthocyanin in the leaves, while the accumulation by nitrogen deficiency was slight. On the other hand, anthocyanin in GC was scarcely changed by the deficiencies. The increase in leucoanthocyanin content caused by phosphorus deficiency was greater than that by nitrogen deficiency both in YD and GC. 2) Effects of Mn deficiency on phenol metabolism were investigated with seedlings of red lettuce (Lacutuca sativa L.) and red cabbage (Brassica oleracea L.). After the seedlings were water-cultured with Mn-deficient culture solutions, phenylalanine ammonia-lyase (PAL) activity, total phenol, anthocyanin, and chlorophyll contents in the leaves were determined. Manganese deficiency caused decreases of PAL activity, total phenol and red anthocyanin was more remarkable. The anthocyanin content changed unrelatedly with the chlorophyll content in the upper leaves of red cabbage. It is suggested that Mn has a direct function in phenol metabolism, especially in anthocyanin formation.

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