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Harada H.,Japan National Agriculture and Food Research Organization | Harada H.,Forestry and Fisheries Research Council Secretariat | Sunaga Y.,Japan National Agriculture and Food Research Organization | Kawachi T.,Japan National Agriculture and Food Research Organization
Soil Science and Plant Nutrition | Year: 2015

Radioactive 137Cs concentrations of forage corn (Zea mays L.) and Italian ryegrass (Lolium multiflorum Lam.) in a double cropping system under continuous cattle farmyard manure (FYM) application were observed for more than 2 years after the Fukushima Daiichi Nuclear Power Station accident in 2011. The experiment field is located 110 km southwest of the Fukushima Daiichi Nuclear Power Station, and the soil contains 137Cs of 920 Bq kg−1 on average. For crop cultivation, nitrogen fertilizer was applied in addition to FYM. The 137Cs concentrations in corn decreased significantly between 2011 and 2012, but only differed significantly between 2012 and 2013 for the plot with no FYM application. For Italian ryegrass, no significant differences were observed between the harvest in 2012 and 2013 despite the FYM application rate. To minimize corn 137Cs concentrations, the FYM application rate should be more than and equal to 30 Mg ha−1 when FYM is used as the major nutrient source. Exchangeable potassium oxide (K2O) greater than around 0.3 g kg−1 was mostly maintained with the FYM application rates. Corn 137Cs concentration appeared to increase at exchangeable K2O levels below 0.15 g kg−1. These results suggest that continuous FYM application can maintain soil nutrients including K2O and thereby control radioactive Cs transfer from the soil. FYM application rate of 30 Mg ha−1 is within the levels recommended by the prefectural governments around Fukushima Prefecture for crop production before the accident. These levels are sufficient to decrease the radioactive Cs concentrations for corn. However, unlike corn, differences in soil chemical properties by FYM application did not affect 137Cs concentrations in Italian ryegrass in this study, although low exchangeable K2O seemed to increase concentrations of stable 133Cs. Further experiments should be conducted to understand the observed differences between corn and Italian ryegrass. © 2015 Japanese Society of Soil Science and Plant Nutrition.


Hamamoto S.,University of Tokyo | Dissanayaka S.H.,Rajarata University | Kawamoto K.,Saitama University | Nagata O.,Japan National Agricultural Research Center | And 3 more authors.
European Journal of Soil Science | Year: 2016

Gas and water transport in peat soil are of increasing interest because of their potentially large environmental and climatic effects under different types of land use. In this research, the water retention curve (WRC), gas diffusion coefficient (Dg) and air and water permeabilities (ka and kw) of layers in peat soil from two profiles were measured under different moisture conditions. A two-region Archie's Law (2RAL)-type model was applied successfully to the four properties; the reference point was taken at -9.8kPa of soil-water matric potential where volume shrinkage typically started to occur. For WRC in the very decomposed peat soil, the 2RAL saturation exponents (n) obtained for both the wetter (nw) and drier regions (nd) were smaller than those for the less decomposed peat. For Dg, the saturation exponent in the wetter region was larger than that in the drier one for all layers, which indicated enhanced blocking effects of water on gas diffusion in the wetter region. For the peat layers within each soil, there was a linear relation between saturation exponents in the drier region for ka and Dg. The larger saturation exponent of the wetter region for kw in peat than in sand suggests a need for specific hydraulic functions for peat soil. The 2RAL model for Dg agreed well with measured data, and performed better than existing unimodal models. To facilitate use of the 2RAL for Dg, we developed a simple predictive expression for Dg at the reference point. The pore-network tortuosity factor and equivalent pore diameter for gas transport confirmed very different pore structure and mass transport behaviour for peat soil and uniform sand. © 2016 British Society of Soil Science.


Ohta S.,Japan National Agriculture and Food Research Organization | Endo T.,Japan National Agriculture and Food Research Organization | Shimada T.,Japan National Agriculture and Food Research Organization | Fujii H.,Japan National Agriculture and Food Research Organization | And 8 more authors.
Tree Genetics and Genomes | Year: 2015

Most citrus tristeza virus (CTV) strains infect almost all Citrus species and have caused serious damage on citrus production in many countries. Poncirus trifoliata (trifoliate orange) has a single dominant resistance gene effective against a broad range of CTV strains. P. trifoliata is sexually compatible with Citrus species, and introgression breeding programs have been initiated to introduce the CTV resistance into Citrus. “Kankitsu Chukanbohon Nou 8 Gou” (Nou-8) was developed by crossing Citrus sp. “Kiyomi” with an F1 hybrid derived from Citrus hassaku × P. trifoliata, but it still had undesirable eating traits. In aim to progress marker-assisted introgression breeding for CTV resistance efficiently, we selected 189 DNA markers which could be applied to genotyping for Citrus and P. trifoliata and constructed a genetic linkage map of Nou-8. The map included 189 DNA markers on 10 linkage groups and extended about 722.8 cM in total length. CTV resistance locus was located at 2.4 cM position in linkage group 02_(1), with the same location found when progeny were scored for resistance using an ELISA assay and for DNA marker for CTV resistant (CTV103). Graphical genotypes of Nou-8 and its progeny suggested that (1) 36 % of the chromosome in the BC’2 population were inherited from Nou-8 without any recombination sites, (2) Nou-8 had been already completely substituted by Citrus genotype in two linkage groups, and (3) four of 93 progeny of Nou-8 had recombination sites in the flanking region of the CTV resistance gene locus. © 2014, Springer-Verlag Berlin Heidelberg.


Ohta S.,Japan National Agriculture and Food Research Organization | Endo T.,Japan National Agriculture and Food Research Organization | Shimada T.,Japan National Agriculture and Food Research Organization | Fujii H.,Japan National Agriculture and Food Research Organization | And 8 more authors.
Tree Genetics and Genomes | Year: 2014

Most citrus tristeza virus (CTV) strains infect almost all Citrus species and have caused serious damage on citrus production in many countries. Poncirus trifoliata (trifoliate orange) has a single dominant resistance gene effective against a broad range of CTV strains. P. trifoliata is sexually compatible with Citrus species, and introgression breeding programs have been initiated to introduce the CTV resistance into Citrus. “Kankitsu Chukanbohon Nou 8 Gou” (Nou-8) was developed by crossing Citrus sp. “Kiyomi” with an F1 hybrid derived from Citrus hassaku × P. trifoliata, but it still had undesirable eating traits. In aim to progress marker-assisted introgression breeding for CTV resistance efficiently, we selected 189 DNA markers which could be applied to genotyping for Citrus and P. trifoliata and constructed a genetic linkage map of Nou-8. The map included 189 DNA markers on 10 linkage groups and extended about 722.8 cM in total length. CTV resistance locus was located at 2.4 cM position in linkage group 02_(1), with the same location found when progeny were scored for resistance using an ELISA assay and for DNA marker for CTV resistant (CTV103). Graphical genotypes of Nou-8 and its progeny suggested that (1) 36 % of the chromosome in the BC’2 population were inherited from Nou-8 without any recombination sites, (2) Nou-8 had been already completely substituted by Citrus genotype in two linkage groups, and (3) four of 93 progeny of Nou-8 had recombination sites in the flanking region of the CTV resistance gene locus. © 2014, Springer-Verlag Berlin Heidelberg.


Okura M.,Japan National Agriculture and Food Research Organization | Takamatsu D.,Japan National Agriculture and Food Research Organization | Takamatsu D.,Gifu University | Maruyama F.,Tokyo Medical and Dental University | And 11 more authors.
Applied and Environmental Microbiology | Year: 2013

Streptococcus suis strains are classified into 35 serotypes on the basis of the antigenicity of their capsular polysaccharides (CPs). CP synthesis genes are known to be clustered on the chromosome (cps gene cluster). The entire cps gene clusters of S. suis have so far been sequenced in 15 serotypes and found to be located between orfZ and aroA. In this study, to provide comprehensive information about S. suis CPs, we sequenced the entire cps gene clusters of the remaining serotypes and analyzed the complete set of S. suis cps gene clusters. Among the 35 cps gene clusters, 22 were located between orfZ and aroA, whereas the other 13 were flanked by other gene(s) on the chromosomes, and the chromosomal locus was classified into five patterns. By clustering analysis, the predicted products of cps genes found in the 35 serotypes were assigned into 291 homology groups, and all serotypes possessed a serotype-specific gene, except for serotypes 1, 2, 1/2, and 14. Because of the presence of genes encoding flippase (wzx) and polymerase (wzy), CPs of all serotypes were thought to be synthesized by the Wzx/Wzy pathway. Our data also implied the possibility of the transfer of the entire or partial cps gene clusters among S. suis strains, as well as the influence of spontaneous mutations in a single gene or a few genes on the antigenicity of some serotypes. Accumulation of these gene transfers and smallscale mutations may have generated the antigenic diversity of S. suis CPs. © 2013, American Society for Microbiology.

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