Studies on the humus forms of forest soils     

Seiichi Ohta  Kyoichi Kumada 《Soil Science and Plant Nutrition》2013,59(2):149-158

Samples described in the previous paper were analyzed for humus composition by the method of Kumada el al,, elementary composition of humic acids, nitrogen distribution among humic acid, fulvic acid, and humin, and organic matter composition by the modified Waksman method. The samples obtained by physical fractionation from each horizon of Higashiyama soil were as follows: f₁ and f₂ from the L layer, f₁, f₂ and f₃ from the F layer, f₁ f₂, sand, silt, and clay fractions from the H-A and A horizons.

With the progress of decomposition, the following tendencies were rather clearly observed.

The extraction ratio of soluble humus, amounts of humic acid and fulvic acid, and PQ, value tended to increase with some exceptions. The degree of humification of humic acid proceeded. Most humic acids belonged to the Rp type, but those of the clay fractions belonged to the B type.

As for the elementary composition of humic acid, transitional changes from the Lf₁ to the clay fraction of the A horizon were observed. But differences in elementary composition among humic acids were far less, compared with those among whole fractions.

Nitrogen contents in humic, fulvic, and humin fractions increased with the progress of decomposition and humiliation, and the largest relative increase was found in fulvic acid nitrogen.

According to the modified Waksman's method, the amounts of residues and protein increased, while the total amounts of each extract, except for the HCl extract, and the amounts of sugars and starch, phenolic substances, hemicelluloses and pectin, and cellulose decreased. Sugars and starch comprised only a small portion of the hot water extract, and polyphenols substances comparable to sugars and starch were also found in the extract. Hemicelluloses and pectin accounted for only about one-half of the HCl extract. Several characteristic differences in the elementary composition of extracts and residues were found.

Pheopigments existed in benzene-ethanol extracts and their amounts seemed to decrease from Lf₁ to Ff₂.  相似文献   

Studies on the humus forms of forest soils     

Seiichi Ohta  Kyoichi Kumada 《Soil Science and Plant Nutrition》2013,59(3):355-364

The results of elementary analysis of each fraction separated physically from each horizon of five forest soils were described.

The biggest fraction was Lf₂ (fresh litter) in L layers, Ff₂ (>2 mm) or Ff₂ (2-1 mm) is F layers and Hf₄ in H layers.

Of all the changes in various parameters which accompanied decomposition and humification, the change in C/N ratio was the most obvious; the C/N ratio for plant remains easily decreased to 25 or 30 during decomposition, but any further decrease in this value occurred with difficulty. It was specifically pointed out that Hf₇ and Hf₂ were fairly different materials from the other fractions.

As for A horizons, both carbon and nitrogen contents increased, and CIN ratios decreased in the order of sand, silt and clay fractions.  相似文献   

Stimulatory effect of aluminum on the growth of tea pollen tubes     

Hiromi Yokota  Ikuyo Takamura  Fumiko Ishikawa  Miwako Ohta  Shigeki Konishi 《Soil Science and Plant Nutrition》2013,59(2):457-461

It is well known that when inorganic elements such as boron (B), calcium, cobalt, and manganese are added to media in combination or alone, they stimulate the germination and/or tube growth of various kinds of pollen (Schmücker 1933; Loo and Hwang 1944; Yamada 1958; Brewbaker and Kwack 1963). Among these elements, the stimulatory effect ofB is the most effective and generally recognized. Aluminum (Al) belongs along with B to Group IIIa in the periodic table, and Fähnrich and Ultlich (1964) reported that Al inhibited the germination and growth of the pollen tube of Petunia hybrida and Antirrhinum majus. However, stimulatory effects of Al on pollen germination or pollen tube growth had not been previously reported.  相似文献   

Factors affecting the dynamics of vegetation in the landscapes of shimokamagari Island,southwestern Japan     

Nobukazu Nakagoshi  Yoko Ohta 《Landscape Ecology》1992,7(2):111-119

On Shimokamagari, an island of the Seto Island Sea, patterns of vegetation in the landscape were studied using vegetation maps. Relationships between social and economic changes, site conditions and the vegetation were examined from a historical perspective. In the process of economic development, mandarin orange production became important on this island. However, over-production, a reduction in the price of mandarin oranges and low-temperature damage to orange trees caused large citrus orchards to be abandoned. A plant community dominated by kudzu appeared in the abandoned orchards and the pine forests, as well. These changes in orchards were connected with the natural site conditions, such as soil, geology, inclination, elevation, direction of slope, and also with artificial conditions, such as density of working paths. Another factor causing change was the replacement of the organic fertilizer of litter from forests by chemical fertilizer since the 1960's. As a result, medium and small forests of pine became tall forests and tall forests of pine changed into tall oak forests. In the human-dominated areas, the major factors affecting the process of vegetation were economic activities, and after the abandonment of the farm-lands, forest succession were controlled by natural site conditions. This paper was presented at the World-Congress of Landscape Ecology in Ottawa, 1991 Titles are tentative translations for original titles in Japanese by the authors.  相似文献   

Antibody responses of swine to type A influenza viruses in the most recent several years.     

H Goto  M Takai  H Iguchi  W Benkele  C Ohta  Y Yamamoto  H Kida  S Noro  N Sakurada 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(2):235-241

A serological survey was conducted on 4,080 swine sera collected for the years 1985-90. The swine sera positive to A/New Jersey/8/76 (swine type H1N1) strain were observed in annual (10-20%) and monthly (20-40%) incidences during the observation period except for occasional months. Antibodies to recent human H1N1 viruses in swine were recognized in relation to the human H1N1 influenza epidemics. Antibody responses of swine to human H3N2 strains appeared irrespective of human epidemics with the virus in the years 1985-87. However, in 1988 almost no antibodies to three human H3N2 isolates of 1983-88 were observed for this year except a few months though the human epidemic occurred in the area. Although in 1989-90 many swine had antibodies to the three strains in the percentage of 3 to 35, no antibody to the latest isolate, A/Hokkaido/20/89 (H3N2), was found for almost all the months of both years. These findings differed markedly from the possible relationship between the prevalence of H3N2 virus-antibodies in swine and the human influenza epidemics, which were described previously in many reports including our studies.  相似文献   

Role of complement in the pathogenicity of fowlpox virus infection in chickens and chicken embryos   总被引：3，自引：0，他引：3  

H Ohta  Y Yoshikawa  K Yamanouchi  Y Ishijima  K Komine  H Okada 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1988,50(1):145-152

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4′,6‐dimethoxyisoflavone‐7‐O‐β‐D‐glucopyranoside (wistin) is a peroxisome proliferator‐activated receptor γ (PPARγ) agonist that stimulates adipocyte differentiation          下载免费PDF全文

Matoki Sanada  Ryuichi Hayashi  Yoshimasa Imai  Fumiya Nakamura  Tomoyo Inoue  Shinji Ohta  Hiroyuki Kawachi 《Animal Science Journal》2016,87(11):1347-1351

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Quantitative structure-activity study of herbicidal N-aryl-3,4,5,6-tetrahydrophthalimides and related cyclic imides     

Hiroki Ohta  Tetsuo Jikihara  Ko Wakabayashi  Toshio Fujita 《Pesticide biochemistry and physiology》1980,14(2):153-160

The quantitative relationship between structure and inhibitory activity against the root growth of sawa millet of 30 N-aryl-3,4,5,6-tetrahydrophthalimides and 88 related N-aryl cyclic imide compounds (3-aryl-1,5-tetramethylenehydantoins, 4-aryl-1,2-tetramethylenetriazolidine-3,5-diones, and their thiocarbonyl analogs) was analyzed by means of physicochemical parameters of the aryl substituents and regression analysis. The results showed that, in each series of these classes of compounds, the position-specific steric effects of aromatic substituents, as represented by Verloop's STERIMOL values, are highly important in determining the inhibitory potency of the compound.  相似文献   

Evaluation of duodenal perfusion by contrast‐enhanced ultrasonography in dogs with chronic inflammatory enteropathy and intestinal lymphoma     

Khoirun Nisa  Sue Yee Lim  Masayoshi Shinohara  Tatsuyuki Osuga  Nozomu Yokoyama  Masahiro Tamura  Noriyuki Nagata  Kazuyoshi Sasaoka  Angkhana Dermlim  Rommaneeya Leela‐Arporn  Tomoya Morita  Noboru Sasaki  Keitaro Morishita  Kensuke Nakamura  Hiroshi Ohta  Mitsuyoshi Takiguchi 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(2):559-568

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Treatment with the MAPK kinase inhibitor U0126 during the first two hours of in vitro maturation improves bovine oocyte developmental competence          下载免费PDF全文

T Shinohara  Y Ohta  N Kawate  M Takahashi  N Sakagami  T Inaba  H Tamada 《Reproduction in domestic animals》2018,53(1):270-273

This study examined the effects of treatment with U0126, which inhibits MAPK by inhibiting MAPK kinase, during the first 2 hr of in vitro maturation on bovine developmental competence and on gap junction (GAPJ) communication between the oocyte and cumulus cells. The percentage of oocytes developing to the blastocyst stage in the group treated with 5 μM U0126 (28%) was significantly higher than that in controls (15%, p < .05), while that in the group treated with 10 μM U0126 (18%) was not. Breakdown of the GAPJs was delayed in the group treated with 5 μM U0126 when compared to controls, as estimated by immunohistochemical examination of connexin 43, which is a primary constituent of the GAPJs. These results indicate that treatment with 5 μM U0126 during in vitro maturation delays GAPJ breakdown and improves bovine oocyte developmental competence.  相似文献