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21.
Junta Yanai Nanami Inoue Atsushi Nakao Masahiro Kasuya Kaori Ando Toshiya Oga Takayuki Takayama Hiroyuki Hasukawa Kunihiko Takehisa Akira Takamoto Kazuki Togami Tomoki Takahashi 《Soil Use and Management》2023,39(2):785-793
To prove the hypothesis that paddy rice utilizes soil nonexchangeable potassium (neK) and causes associated structural changes in clay minerals, K status and clay mineralogy of 22 surface soils from three paddy fields under long-term fertilizer management for 51–93 years were investigated. Soil neK content was determined as the difference between 1 mol L−1 hot HNO3 extractable K and 1 mol L−1 ammonium acetate exchangeable K. Clay mineralogy was identified by X-ray diffraction (XRD). The radiocesium interception potential (RIP), an index of frayed edge sites in the interlayer sites of 2:1 type clay minerals, was also determined. The neK contents under the -K and NPK treatments were considerably lower than those under the unfertilized treatment in all the fields, indicating the exploitation of soil neK by rice. XRD analysis of the clay samples revealed 7% shift from the 1.0 peak to 1.4 nm one under the -K treatment compared with the unfertilized one, and the amounts of neK were negatively correlated with those of RIP (p < .01), suggesting the expansion of interlayer spaces of the 2:1 type phyllosilicates such as mica due to the release of neK. In addition, the neK content positively correlated with K balance of the long-term experiments (p < .05). The differences of neK between unfertilized K and -K treatments corresponded to 22–157 kg K ha−1, or 0.42–1.68 kg K ha−1 year−1. In conclusion, utilization of considerable amount of soil neK under K depleted conditions should be considered to establish sustainable K management for paddy rice. 相似文献
22.
Nagao K Okazaki R Nakamura T Miura YN Osawa T Bajo K Matsuda S Ebihara M Ireland TR Kitajima F Naraoka H Noguchi T Tsuchiyama A Yurimoto H Zolensky ME Uesugi M Shirai K Abe M Yada T Ishibashi Y Fujimura A Mukai T Ueno M Okada T Yoshikawa M Kawaguchi J 《Science (New York, N.Y.)》2011,333(6046):1128-1131
Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system. 相似文献
23.
Tomoki Takahashil Chang-Young Park Hideharu Nakajima Hiroyuki Sekiya Kazunobu Toriyama 《Soil Science and Plant Nutrition》2013,59(1):163-173
We examined the relationship between the form of iron and the tillability (defined as the degree of ease of pulverizing a soil into small clods) of soils in upland fields that had been converted from paddy fields. The amount of iron (Fe.e) extractable with acetate buffer (pH 3.0) decreased from 0.959 g kg-1 in a field that has been continuously used as a paddy field to 0.104 g kg-I in a field that had been converted into an upland field for a period of 5 y. There was no significant change in the free iron oxide content under upland conditions. These results indicate that ferric iron oxides are gradually crystallized to less reactive forms after the conversion of a paddy field into upland conditions. Both soil tillability (represented by the mean clod diameter after tillage) and the stability of the soil microstructure (represented by the sediment volume) also increased during the 3-y period after conversion and then remained constant for the last 2-y period of the study. On the basis of these results, two mechanisms for the improvement of soil tillability can be proposed as follows: crystallization of ferric iron oxides increased their resistance to microbiological reduction and due to this stabilization the iron oxides as a cementing reagent that contributed to the soil microstructure, which in turn affected the soil tillability. During the first year after drainage, however, there was no significant correlation between the soil tillability and amount of Feac, presumably because the soil was not sufficiently dry in the first year after conversion, and the iron oxides did not affect appreciably the soil structure. 相似文献
24.
Effect of water surface condition on survival,growth and swim bladder inflation of yellowfin tuna,Thunnus albacares (Temminck and Schlegel), larvae 
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下载免费PDF全文 Tomoki Honryo Teruyoshi Tanaka Angel Guillen Jeanne B Wexler Amado Cano Daniel Margulies Vernon P Scholey Maria S Stein Yoshifumi Sawada 《Aquaculture Research》2016,47(6):1832-1840
Early‐stage mortality due to surface water tension‐related death and due to sinking to the tank bottom was investigated for yellowfin tuna, Thunnus albacares (YFT), larvae. Different aeration rates and rearing water surface conditions were examined to evaluate the effect on larval survival, swim bladder inflation and growth. The percentage survival of yolk sac larvae was significantly higher when the rearing water surface was covered with fish oil at aeration rates of 0 and 50 mL min?1. The highest mortality occurred at the highest aeration rate of 250 mL min?1 regardless of surface water condition. A second experiment was conducted twice under different water surface conditions: the water surface was covered by fish oil (FO), skimmed of fish oil (SS), and was not treated (NC). The percentage survival was not significantly different between treatments after 7 days of feeding. In contrast to the survival, the proportion of larvae with inflated swim bladders was significantly higher for the NC and SS groups than that of the FO group. Results of these experiments indicate that the addition of oil to the rearing water surface without its removal interferes with the initial swim bladder inflation in YFT larvae. These results also indicate that YFT larvae need to obtain (gulp) air at the water surface for initial swim bladder inflation, and success of initial swim bladder inflation may be crucial for their survival. 相似文献
25.
Tomoki Honryo Tokihiko Okada Michio Kurata Toshihiro Tamura Yasunori Ishibashi 《Aquaculture Research》2014,45(7):1109-1115
We have previously reported that night‐time lighting prevents the mass death of Pacific bluefin tuna (PBT) juvenile due to collision and/or contact with the walls of sea cages, immediately after transfer to the cages, and that night‐time lighting does not negatively impact fish stress levels. However, the period of night‐time lighting should be limited to minimize negative impacts on the surrounding environment and aid management. Therefore, we investigated the optimal period of night‐time lighting by evaluating the whole‐body cortisol and glucose levels as stress parameters, growth performance and survival of PBT juvenile in four cages with different periods of night‐time lighting (i.e. unlit, 4‐day, 8‐day and 12‐day lighting). The results showed that almost all fish were died 1 day after transfer to the unlit cage. In comparison, the other groups (4‐day, 8‐day and 12‐day lighting) had high survival rates (92.5–96.0%) without significant difference. However, in the 4‐day‐lighting group, an obvious stress response was recorded on day 5, and growth performance was significantly lower. In the 8‐day‐lighting group, whole‐body cortisol levels were slightly elevated on day 9; however, significantly elevation was not recorded on day 12. These results indicate that the recommended lighting period of night‐time lighting in sea cages is 8–12 days. 相似文献
26.
Mizuhiko Nishida Koji Yoshida Tomoki Takahashi 《Communications in Soil Science and Plant Analysis》2018,49(14):1695-1706
This study was performed to investigate changes in available soil phosphate associated with temperature under submerged conditions and to explore the possibility for estimating those under submerged conditions during the early growth (tillering) stage of rice plants (Oryza sativa L.). An incubation experiment was conducted under submerged conditions at three temperatures (10°C, 17.5°C and 25°C) using paddy soils collected over a widespread area in Japan. In most soils, significant positive correlations were observed between available soil phosphate and cumulative temperature to 650°C, which corresponded to the tillering stage in Japan. Relationships between the regression formulae of the available phosphate against cumulative temperature to 650°C and soil chemical properties measured in air-dried soil were investigated. The results indicate that the available phosphate of paddy soil against cumulative temperature during tillering stage under submerged conditions can be estimated from the results of air-dried soil analyses which can be conducted before a crop season. 相似文献
27.
Tomoki Honryo Michio Kurata Dario Sandval Saki Yamao Amado Cano Yoshifumi Sawada 《Fisheries Science》2018,84(3):553-562
This study aimed to examine the effect of different water temperatures and light intensities on swim bladder inflation (SBI) and growth of red sea bream Pagrus major larvae to improve rearing techniques for this species. Two sets of experiments were conducted: different rearing temperatures were used in experiment 1 (19, 21, 23, and 25 °C), and different light intensities in experiment 2 (250, 1000, 4000, and 16,000 lx). Water temperature did not affect SBI frequency, but SBI initiation was accelerated at higher temperature, i.e., it was initiated on 3 days post-hatching (dph) at 25 °C and on 6 dph at 19 °C, suggesting that the promotion period for SBI, which needs a surface skimmer to be run, also accelerated with increasing temperature in red sea bream larviculture. A higher temperature also significantly promoted larval growth, although the notochord of larvae at SBI initiation was shorter at higher temperatures. Light intensity had no effect on either the initiation or the frequency of SBI. However, light intensity of 250 lx significantly reduced early larval growth compared to light intensities higher than 1000 lx. These results indicate that light at an intensity greater than 1000 lx at the water surface is suitable for the early larviculture of red sea bream. 相似文献
28.
Junichiro Takeuchi Chie Imagawa Toshihiko Kawachi Koichi Unami Shigeya Maeda Tomoki Izumi 《Paddy and Water Environment》2010,8(2):175-187
A distributed hydro-environmental model is developed that achieves detailed analysis of the movement of water at a field-plot-scale
resolution in a mesoscale watershed including lowland areas where, especially for agricultures, it is an essential need to
get rid of redundant groundwater by drainage facilities such as rivers, canals and/or underdrains. For this, the problem geometry
is meshed with unstructured cells of triangular shape. Profile of a column cell is zoned into two: surface zone and groundwater
zone in which water movement is represented by combined tank and soil moisture sub-models, and well-defined two-dimensional
unconfined shallow groundwater flow sub-model, respectively. The top-two sub-models serve to evaluate evapotranspiration,
infiltration, soil water content, lateral surface water flow, and vertical percolation. The vertical percolation so evaluated
is given as longitudinal recharge to the bottom sub-model for computing groundwater flow. Surface water–groundwater interactions
through beds and stream-banks of perennial and ephemeral canals are considered by treating the canal courses as internal boundaries
in the groundwater flow model. The finite volume method (FVM) that allows of unstructured mesh and produces conservative solutions
is employed for groundwater flow computation. The model developed is applied to an actual watershed which includes a low-lying
paddy area to quantify the hydrological impact of land-use management practices over a period of 29 years in which the farmland
consolidation project was implemented and part of the paddy fields were converted to upland crop fields and housing lands.
From the results obtained, it is concluded that the model presently developed lends itself to water—as well as land-use management
practices. 相似文献
29.
Shimizu M Tanaka R Fukuyama T Aoki R Orito K Yamane Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(3):271-276
Cardiac remodeling and angiotensin II-forming enzyme activity of the left ventricle on chronic pressure overload were studied in male Syrian hamsters, whose chymase activity is similar to that of dogs. Pressure overload was achieved by banding at the ascending aorta (aortic stenosis). Echocardiography, histological analysis, and analysis of cardiac angiotensin-converting enzyme and chymase-like activities were performed. At 10 weeks after banding, concentric hypertrophy of the left ventricle was evident. At 20 weeks after banding, the ventricular weight-to-body ratio, cardiac fibrosis, and cardiac chymase-like activity were significantly increased, while cardiac angiotensin-converting enzyme activity was significantly decreased. This suggests that cardiac chymase, compared with cardiac angiotensin-converting enzyme, was activated against the chronic pressure overload and was responsible for the cardiac remodeling through the formation of angiotensin II. Considering the utility of the rodents, the interspecies similarity of the Ang II-forming pathway, and the effect of chymase in the hamsters, the present model is considered useful for studies evaluating the effect of Ang II and chymase in the canine heart with chronic pressure overload. 相似文献
30.