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Article type: Cover
2012 Volume 83 Issue 4 Pages
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Article type: Appendix
2012 Volume 83 Issue 4 Pages
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2012 Volume 83 Issue 4 Pages
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Article type: Index
2012 Volume 83 Issue 4 Pages
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Article type: Index
2012 Volume 83 Issue 4 Pages
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Article type: Appendix
2012 Volume 83 Issue 4 Pages
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2012 Volume 83 Issue 4 Pages
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Article type: Appendix
2012 Volume 83 Issue 4 Pages
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Yasuko FUKUDA, Takeshi HOSOKAWA, Yuji NATSUME, Yuji FUTAMURA, Ken-ichi ...
Article type: Article
2012 Volume 83 Issue 4 Pages
381-388
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We conducted a series of field experiments in 2005 and 2008 to compare the characteristics of the low-phytate soybean (Glycine max (L) Merr.) line CX1834 with those of the cultivar 'Enrei' by comparing plant growth, yield, and the contents of phytic acid, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), crude protein, and isoflavone. The length of the main stem, number of nodes, and shoot dry weight of the low-phytate line were higher than those of 'Enrei' at full maturity in both years. The number of pods, number of seeds per pod, number of seeds per plant, and seed yield were also higher in the low-phytate line. There was no significant difference in the total phosphorus (TP) content of seeds from the two lines in 2005, but TP was higher in the low-phytate line in 2008. The phytic acid content was around 50% lower in the low-phytate line, whereas the inorganic P content was five times that in 'Enrei' in both years. The K, Ca, Mg, crude protein, and isoflavone contents were similar. In Enrei, the phytic acid content increased from 20 to 30 days after anthesis, and increased linearly until full maturity. In the low-phytate line, in contrast, phytic acid did not accumulate with increasing seed maturity, indicating that the synthesis of phytic acid was suppressed. The results suggest that decreased phytic acid synthesis did not affect soybean growth, yield, nutrient accumulation, or seed quality.
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Takanori OOMORI
Article type: Article
2012 Volume 83 Issue 4 Pages
389-395
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I investigated the relationships among the cadmium (Cd) concentrations in low-Cd soils and brown rice as a function of soil pH and irrigation management. Brown rice grown in a dry paddy soil 1 week after heading was assumed to have the highest level of Cd. Using the results of my analysis, I simulated the risk of Cd contamination of brown rice as a function of soil Cd concentration and soil pH. I estimated the Cd concentration in brown rice by regression analysis with soil pH and soil Cd concentration (extracted in 0.1 mol L^<-1> HCl) as independent variables, and obtained the following equation: Z=0.449X-0.336Y+2.607(R^2=0.79) where Z is the estimated rice Cd concentration, X is the soil Cd concentration, and Y is the soil pH. Using the equation, I performed a risk simulation for rice Cd concentration using a dataset of 500 soils with varying soil pH and soil Cd concentrations. The equation will help farmers determine which area or field should be improved (e.g., by increasing the pH) and will help them reduce the amount of soil improvement materials required, thereby providing an easy and effective way to improve the soil and reduce the risk of Cd contamination in brown rice.
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Masakazu SHIWA, Eiji NISHINO, Yoshihiro IMAMURA
Article type: Article
2012 Volume 83 Issue 4 Pages
396-404
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A large quantity of pruned shoots accumulates between tea hedges as a result of skiffing and pruning of the canopy after the second crop in each year, and we are concerned that this litter influences the behavior of fertilizer nitrogen (N) in the space between the hedges. We investigated the nitrous oxide (N_2O) emission potential and fluxes to clarify the behavior of applied fertilizer N in these spaces. The litter decreased the amount of applied fertilizer that reached the soil compared with areas where the litter was removed. This suggests that either the applied N was fixed within the litter or it underwent denitrification in the litter or surface soil. We measured the N_2O emission potential in the litter, the surface soil, and the soil below 10 cm using laboratory incubations at 25 ℃. The litter produced 671 μg N_2O-N g^<-1> during the 14-day incubation, equal to 134 times the soil emission. Annual N_2O emission was 102 kg N_2O-N ha^<-1> with litter, versus 21 kg N_2O-N ha^<-1> without litter. The N_2O emission factor (N_2O-N emitted for applied fertilizer-N) was 17.0% in the litter areas. When fertilizer was applied on accumulated litter, the N loss increased and soil N did not improve sufficiently. Therefore, we tried accelerating the decomposition of this organic matter by deep plowing to control N_2O emission between the hedges. This decreased N_2O emission to 41% of the value in plots with accumulated litter.
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Koji ODAHARA, Yusuke FUKUSHIMA, Masato ARAKI, Akira KANEKO, Kouichiro ...
Article type: Article
2012 Volume 83 Issue 4 Pages
405-411
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Continuous cropping has led to declining soybean productivity. We investigated the relationship between soybean yield and soil fertility in fields with different histories of upland and paddy rice cultivation in Japan's Chikugo River basin to identify the primary factors that influence soybean productivity. The total soil carbon (C) and nitrogen (N) contents and the available N content decreased with repeated soybean cropping. The air-filled pore ratio of the soil at a water potential of -3.1 kPa decreased as the soil's C content decreased. Available N decreased during soybean cultivation, but partially recovered within half a year. Soybean yield decreased with increasing number of soybean crops; it was weakly but significantly correlated with available N (P<0.05), but was strongly and significantly correlated (P<0.01) with the soil's air-filled pore ratio at a water potential of -3.1 kPa. These results suggest that soybean productivity could be improved primarily by increasing soil porosity and secondarily by increasing available N.
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Kanako FUJIWARA, Azusa SHIGEMASA, Tomoyuki KASHIMA, Hiroki ONO, Yoshik ...
Article type: Article
2012 Volume 83 Issue 4 Pages
412-417
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An iron coating for rice seeds increases the specific gravity and improves direct sowing in flooded paddies. This reduces labor requirements and improves rice production handling system. The coated seeds also exhibited desirable antimicrobial activity, but the reason for this activity was unclear. We examined the antimicrobial activity after inoculation of the coated seeds with pathogenic Pseudomonas plantarii in sterilized deionized and distilled water. The bacterium's growth rate decreased markedly and the bacteria disappeared. Seed coated with iron at ratios of 0.1 and 1.0 (w/w) showed similar levels of antimicrobial activity. The concentration of hydroxyl free radicals increased with increasing iron ratio. The presence of Fe^<2+> and hydroxyl radicals was confirmed by chemoluminescence and electron spin resonance methods, respectively. When the radicals were scavenged by chlorogenic acid, the main radical components were hydroxyl radicals. The antimicrobial activity appears to result from damage caused by the radicals, and a hydroxyl radical concentration of around 80 nM completely eliminated the bacteria. The presence of both Fe^<2+> and oxygen in solution is essential for hydroxyl radical production, and autoxidation of F^<2+> is believed to induce production of these radicals, though without the H_2O_2 that occurs in the Fenton reaction. Radical formation continued for at least 12 days in the laboratory, and we predict that small amounts of radicals would be produced shortly after adding water to paddy soils, thereby triggering autoxidation and free radical formation and extending the antimicrobial function.
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Katsuhiko NAGASAKA, Syuhei YAMASAKI, Kumiko MOCHIDUKI, Tsutomu HOSINO
Article type: Article
2012 Volume 83 Issue 4 Pages
418-421
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Yuiko TOMIZAWA, Tetsuo YAGI, Junji FUJIKURA
Article type: Article
2012 Volume 83 Issue 4 Pages
422-426
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Takahiro ONO, Naoki MORITSUKA, Tatsuya INAMURA
Article type: Article
2012 Volume 83 Issue 4 Pages
427-430
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Tamotsu OKAMOTO
Article type: Article
2012 Volume 83 Issue 4 Pages
431-433
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Takehiko MATSUMOTO, Toshiya SAIGUSA
Article type: Article
2012 Volume 83 Issue 4 Pages
434-437
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Shigeru ARAKI
Article type: Article
2012 Volume 83 Issue 4 Pages
438-448
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Takashi IKKA, Akio MORITA, Hiroyuki KOYAMA
Article type: Article
2012 Volume 83 Issue 4 Pages
449-454
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Syuntaro HIRADATE
Article type: Article
2012 Volume 83 Issue 4 Pages
455-461
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Kaori MATSUOKA, Naoki MORITSUKA
Article type: Article
2012 Volume 83 Issue 4 Pages
462-470
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Jiro SETO, Naoto KATO, Kuni SUEYOSHI, Jun WASAKI, Naoki MORITSUKA, Yos ...
Article type: Article
2012 Volume 83 Issue 4 Pages
471-477
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Takashi KOSAKI, Katsutoshi SAKURAI
Article type: Article
2012 Volume 83 Issue 4 Pages
478-482
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Masahiko SAIGUSA, Takeshi OHTA, Takuro SHINANO, Kiwamu MINAMIZAWA, Tat ...
Article type: Article
2012 Volume 83 Issue 4 Pages
483-486
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Naoki MORITSUKA, Kaori MATSUOKA
Article type: Article
2012 Volume 83 Issue 4 Pages
487-494
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Hiroshi OBARA, Toshiaki OHKURA, Yusuke TAKATA, Kazunori KOHYAMA, Yuji ...
Article type: Article
2012 Volume 83 Issue 4 Pages
495-501
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Kaori GOTO
Article type: Article
2012 Volume 83 Issue 4 Pages
502-503
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Satoshi MATSUMOTO
Article type: Article
2012 Volume 83 Issue 4 Pages
504-505
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Yusuke TAKATA, Kazuyuki YAGI
Article type: Article
2012 Volume 83 Issue 4 Pages
506-507
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Article type: Bibliography
2012 Volume 83 Issue 4 Pages
508-511
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Article type: Appendix
2012 Volume 83 Issue 4 Pages
512-513
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[in Japanese]
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2012 Volume 83 Issue 4 Pages
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[in Japanese]
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2012 Volume 83 Issue 4 Pages
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Article type: Appendix
2012 Volume 83 Issue 4 Pages
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2012 Volume 83 Issue 4 Pages
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Article type: Cover
2012 Volume 83 Issue 4 Pages
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