Impact of a 5-year winter cover crop rotational system on the molecular diversity of arbuscular mycorrhizal fungi colonizing roots of subsequent soybean

The impact of winter cover crops, specifically wheat (Triticum aestivum L.), red clover (Trifolium pratense L.), and rapeseed (Brassica napus L.) or winter fallow, on community composition of arbuscular mycorrhizal fungi (AMF) in subsequent soybean roots was investigated in a 5-year field trial on andosolic soils in Japan. Soybean roots were sampled at full-flowering and analyzed for AMF communities using a partial LSU rDNA region. Phylogenetic analysis detected 22 AMF phylotypes, including eight Glomus, three Gigaspora, two Scutellospora, three Acaulospora, two Rhizophagus, and one of Funneliformis, Diversispora, Paraglomus, and an unknown glomeromycete in the roots. The 5-year rotation of different winter cover crops or winter fallow did not impact the molecular diversity of AMF communities colonizing the roots of subsequent soybean. In all of the rotations, Glomus and Gigaspora phylotypes were common to soybean roots over the 5-year period. Redundancy analysis (RDA) demonstrated that AMF communities in the roots of subsequent soybean were not significantly different among winter cover crop rotations or fallow. However, AMF communities in soybean roots were clearly influenced by rotation year suggesting that climate or other environmental factors were more important than winter cover cropping system management.     

Modified phases of diamond formed under shock compression and rapid quenching

Two modified forms of carbon were quenched by a rapid-cooling technique from graphite sheets shock-compressed to 65 gigapascals and 3700 K. One form, ;;n-diamond," which was obtained from the most rapidly cooled part, has a crystal structure close to that of cubic diamond. The other form, found in the relatively slow-cooled part, was comparable to an i-carbon prepared by an ion-beam technique. The n-diamond is interpreted as a metastable form, the same as hexagonal diamond, converted from graphite through a martensitic transition, for which either the region or the path may be different from that of hexagonal diamond. The second form was found to be produced through reconstruction.     

Effect of supplementation of rice bran and fumarate alone or in combination on in vitro rumen fermentation,methanogenesis and methanogens

This study investigated the effect of fumarate (FUM) and rice bran (RB), alone and together, on in vitro rumen fermentation, methanogenesis and methanogens. In vitro incubation was performed with six media that were either unsupplemented (control) or supplemented with 10% RB, 5 mmol/L FUM, 10% RB + 5 mmol/L FUM, 10 mmol/L FUM, or 10% RB + 10 mmol/L FUM. Methane (CH₄) production, dry matter digestibility, CH₄ per digested dry matter, total short‐chain fatty acid (SCFA) production, proportion of SCFA, acetate : proprionate ratio, production of NH₃‐N, and population density of rumen microbes were determined. Supplementation with 10% RB + 10 mmol/L FUM yielded a 36% decrease in CH₄ production compared to the control. Supplementation of FUM, in the presence or absence of RB, provided increases in total SCFA production and propionate proportion up to 61% and 31%, respectively. Total bacteria, methanogens and protozoa populations were significantly (P < 0.05) decreased with the 10% RB + 10 mmol/L FUM supplementation. The effect of anti‐methanogenesis of FUM was enhanced by the addition of RB. Notably, the CH₄ production attenuation was achieved by 10% RB + 10 mmol/L FUM without reduction of digestibility or of ruminal fermentation.     

Site-level model–data synthesis of terrestrial carbon fluxes in the CarboEastAsia eddy-covariance observation network: toward future modeling efforts

Based on the model–data comparison at the eddy-covariance observation sites from CarboEastAsia datasets, we report the current status of the terrestrial carbon cycle modeling in monsoon Asia. In order to assess the modeling performance and discuss future requirements for both modeling and observation efforts in Asia, we ran eight terrestrial biosphere models at 24 sites from 1901 to 2010. By analyzing the modeled carbon fluxes against the CarboEastAsia datasets, the strengths and weaknesses of terrestrial biosphere modeling over Asia were evaluated. In terms of pattern and magnitude, the carbon fluxes (i.e., gross primary productivity, ecosystem respiration, and net ecosystem exchange) at the temperate and boreal forest sites were simulated best, whereas the simulation results from the tropical forest, cropland, and disturbed sites were poor. The multi-model ensemble mean values showed lower root mean square errors and higher correlations, suggesting that composition of multiple terrestrial biosphere models would be preferable for terrestrial carbon budget assessments in Asia. These results indicate that the current model-based estimation of terrestrial carbon budget has large uncertainties, and future research should further refine the models to permit re-evaluation of the terrestrial carbon budget.     

New multilocus genotypes of <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in Japan

Twelve isolates of Japanese Phytophthora infestans, which differed from the major genotypes US-1, JP-1, JP-2, and JP-3, were analyzed for RG57 fingerprints, mtDNA haplotypes, two allozyme genotypes, and mating types. Genotypes JP-1.1, JP-2.1, JP-2.2, JP-3.1, and JP-4 were newly defined. JP-1.1 and JP-2.1 were isolated discontinuously from potato fields in several years, and JP-1.1 was found in Hokkaido and Kagoshima. These results show that some minor genotypes can overwinter and disperse from their original site.