Syuntaro Hiradate

National Institute for Agro-Environmental Sciences in Japan, Tsukuba, Ibaraki, Japan

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Publications (149)278.96 Total impact

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    ABSTRACT: The relationship between degradation speed of soil-buried biodegradable polyester film in a farmland and the characteristics of the predominant polyester-degrading soil microorganisms and enzymes were investigated to determine the BP-degrading ability of cultivated soils through characterization of the basal microbial activities and their transition in soils during BP film degradation. Degradation of poly(butylene succinate-co-adipate) (PBSA) film was evaluated in soil samples from different cultivated fields in Japan for 4 weeks. Both the degradation speed of the PBSA film and the esterase activity were found to be correlated with the ratio of colonies that produced clear zone on fungal minimum medium-agarose plate with emulsified PBSA to the total number colonies counted. Time-dependent change in viable counts of the PBSA-degrading fungi and esterase activities were monitored in soils where buried films showed the most and the least degree of degradation. During the degradation of PBSA film, the viable counts of the PBSA-degrading fungi and the esterase activities in soils, which adhered to the PBSA film, increased with time. The soil, where the film was degraded the fastest, recorded large PBSA-degrading fungal population and showed high esterase activity compared with the other soil samples throughout the incubation period. Meanwhile, esterase activity and viable counts of PBSA-degrading fungi were found to be stable in soils without PBSA film. These results suggest that the higher the distribution ratio of native PBSA-degrading fungi in the soil, the faster the film degradation is. This could be due to the rapid accumulation of secreted esterases in these soils.
    12/2015; 5(1). DOI:10.1186/s13568-014-0088-x
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    ABSTRACT: To evaluate organic carbon (OC) accumulation processes in peat deposits in tropical mangrove ecosystems, solid-state 13C cross-polarization and magic angle spinning nuclear magnetic resonance signals were measured to determine the OC compositions of decomposed leaves and roots. These account for a large majority of mangrove litters and mangrove peat in a coral reef-type Rhizophora forest on Pohnpei Island, Federated States of Micronesia. Radiocarbon dating was also used to understand the sources of peat deposits at each depth. The mass loss rate of mangrove leaves during 1-year litterbag incubation was much higher than that of roots. These mass loss rates are expected to be affected by the varying chemical characteristics of leaves and roots and the different aerobic/hydrological conditions present in the two litter types during decomposition. The decomposability of individual OC components also varied markedly between leaf and root litters. Significant increases in aryl-C/O-alkyl-C and aliphatic-C/O-alkyl-C ratios and minor increases in the aryl-C/aliphatic-C ratio during leaf decomposition implied that O-alkyl-C was more labile than aryl- and aliphatic-C and that aliphatic-C was also slightly more decomposable than aryl-C, but not significantly so, in leaf litters on the forest floor. Regarding roots, a stable aryl-C/O-alkyl-C ratio during decomposition suggested that aryl- and O-alkyl-C components did not differ greatly in decomposability in the peat deposit, while the minor increase in the aliphatic-/O-alkyl-C ratio and the substantial decrease in the aryl-/aliphatic-C ratio with decomposition implied that aliphatic-C was more recalcitrant than aryl- and O-alkyl-C in the peat. The OC compositional properties were quite homogenous throughout the peat profile, and 14C dating mostly indicated modern, which suggest that large amounts of mangrove roots penetrate to at least 80 cm depth. These findings provide quantitative and qualitative insights into the potential importance of very high production of mangrove fine roots for OC accumulation in peat in tropical mangrove ecosystems.
    Geoderma 05/2015; 245. DOI:10.1016/j.geoderma.2015.01.008 · 2.51 Impact Factor
  • Rota Wagai, Masako Kajiura, Maki Asano, Syuntaro Hiradate
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    ABSTRACT: Organic matter (OM) bound to soil mineral particles (higher-density particles) tends to be more stabilized, enriched in 13C and 15N, and has a lower C:N ratio. Yet how these variations in OM chemistry are linked to the nature of organo-mineral assemblage remains poorly understood, especially in allophanic soils where high amounts of OM are stabilized by interactions with reactive inorganic phases such as short-range-order (SRO) minerals. We thus assessed the extent to which the degree of aggregation and its disruption during fractionation control the distribution and chemistry of the soil organo-mineral particles across six density fractions using a volcanic soil (allophanic Andisol) based on selective dissolution, microscopy (SEM), solid-state 13C NMR spectroscopy and δ13C and δ15N analyses. Intermediate-density fractions (2.0-2.5 g cm− 3) accounted for 63-86% of organic C and N, 73-93% of pyrophosphate-extractable iron and aluminum (Fep, Alp), and 78-95% of oxalate-extractable metals (Feo, Alo) in the bulk soil sample. While air-drying pretreatment had little effect, sonication during fractionation led to (i) fragmentation of both plant detritus and some of the aggregates of 30-100 mm sizes, (ii) release of occluded low-density fraction (< 1.6 g cm− 3) which largely originated from the aggregates of 1.6-2.0 g cm− 3 density range, and (iii) redistribution of organo-mineral particles (15-16% of total OM and 7-19% of the extractable metals) within the intermediate density fractions. Positive correlation of Alp with C:N ratio and negative correlation of Alp with δ15N among the fractions suggest preferential binding of Alp phase (e.g., organo-Al complexes) to decaying plant detritus. Positive correlation of Alo and Feo with δ15N, together with theoretical density calculations of idealistic organo-mineral association modes, suggests that 15N enrichment may be coupled with OM binding to SRO minerals and with the formation of physically-stable aggregates of micron/submicron sizes in accord with our conceptual model (Asano and Wagai, 2014). The general pattern of 13C and 15N enrichment and C:N decline with increasing particle density remained largely unchanged despite the sonication effects detected, indicating that sonication-resistant organo-mineral assemblages largely control the observed patterns. The similarity in the density-dependent changes of OM chemistry between the studied Andisol and the soils with crystalline clay and metal oxide mineralogies in previous studies strongly suggests a common biogeochemical control which deserves further investigation.
    Geoderma 03/2015; 241-242:295-305. DOI:10.1016/j.geoderma.2014.11.028 · 2.51 Impact Factor
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    ABSTRACT: This study examined the recovery, via biotic and abiotic pathways, of a grassland ecosystem after eradication of introduced exotic goats. We used path analyses to evaluate the relative strength of relationships among aboveground biomass, soil chemical properties (carbon, nitrogen, and phosphorus content; soil acidity), presence of nesting seabirds after goat eradication, extent of vegetation degraded by goats before their eradication, plant species composition after removal of goats, and topography. Models including the same variables with different paths were constructed using the Bayesian estimation method, and the best-fit models were constructed by comparing deviance information criterion values. Results of the path analyses demonstrated that vegetation degradation and soil erosion prior to goat eradication increased soil exchangeable acidity, which resulted in limitation of aboveground biomass. Seabird nesting after goat eradication increased the quantity of soil nutrients, possibly through inputs of feces, eggshells, and dead chicks or adults. The increase in nutrients was affected indirectly, via seabird nesting, by topography and vegetation type after goat eradication. The direct and indirect relationships demonstrated by our results suggest the existence of complex interrelationships during recovery of ecosystem function after eradication of exotic mammals.
    Ecosystems 09/2014; 17(6). DOI:10.1007/s10021-014-9780-6 · 3.53 Impact Factor
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    ABSTRACT: Aluminum (Al) accumulators are widely distributed in the plant kingdom but phylogenetic implications of internal Al detoxification mechanisms are not well understood. We investigated differences in the characteristics of Al accumulation (i.e., accumulation potential, chemical form, and localization) in three woody Al accumulators, Symplocos chinensis (Symplocaceae, Ericales), Melastoma malabathricum, and Tibouchina urvilleana (both Melastomataceae, Myrtales). The order of Al accumulation potential under hydroponic conditions was S. chinensis ≈ M. malabathricum > T. urvilleana. Oxalate was at least partly involved in the internal Al detoxification mechanisms in leaves of all three Al accumulators, based on a correlation analysis between Al and organic acid in water and 0.02 M HCl extracts and the 27Al nuclear magnetic resonance spectra of intact leaves. However, the Al forms in the leaves were not simple Al-ligand complexes in a specific cell structure. Al localization in leaf sections differed among the three species. Extremely high levels of Al were found in trichomes of the lower epidermis in leaves of T. urvilleana. These data illustrate that woody Al accumulating angiosperms have independently developed various internal Al tolerance mechanisms in which oxalate plays a significant role.
    Botany 05/2014; 92(5):327-331. DOI:10.1139/cjb-2013-0298 · 1.04 Impact Factor
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    Japanese Geoscience meeting; 04/2014
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    ABSTRACT: Okayama and Tochigi, all sites are under forest. New Zealand sites were Ngahinapouri, Waihora and Whatawhata. They are under pasture. Soil samples were collected from different soil depths (Fig. 1 & Table 1). The degree of SWR was measured as the soil-water contact angle using the SDM and the MED test. The persistence of SWR was determined with the WDPT. MED: Measures the molarity of an ethanol (M) droplet requires for a droplet to infiltrate in 5 s. Contact angle (α i) was measured using following equations. íµí»¾ íµí± = 61.05 − 14.75 ln(íµí±€ + 0.5) cos α i = (γ c / γ L) 1/2 -1 (Carillo et al., SDM Microphotograph of a water droplet placed on an adhesive tape was taken using digital microscope. The soil-water contact angle was directly measured. ~100 o 100 µm  The relationships between SWR parameters and SOC were agreed well with recently published work of Kawamoto et al. (2007) and Karunarathna et al. (2010).  While the Japanese soils had high SOC contents below 10 cm depths, these horizons were not water repellent. Therefore, further studies are scheduled to analyze quality of SOC utilizing a C-solid NMR technique, targeting to characterize surface functional groups of soil organic materials.
    JPGU; 04/2014
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    ABSTRACT: Soil water repellency (SWR) is known to lead to preferential flow and to degrade the soil's filtering efficiency. However, no method is available to quantify directly how SWR affects the transport of reactive solutes. We propose a new method for conducting solute transport experiments in water-repellent soils. It involves sequentially applying two liquids, one water, the other a reference fully wetting liquid, namely aqueous ethanol, to the same intact soil core with air-drying between liquids. We applied this approach to quantify the impact of SWR on the filtering of the herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) in two Andosols. In batch experiments conducted prior to the transport experiments, 2,4-D sorption was not influenced by aqueous ethanol for one soil. However, sorption in the second soil followed the co-solvency theory, which predicts decreasing sorption with increasing solvent fractions. Thus, sorption experiments are necessary to complement our new method. Breakthrough curves were characterized by preferential flow with large initial concentrations, tailing and a long prevalence of solutes remaining in the soil. In the soil in which 2,4-D sorption was unaffected by aqueous ethanol, SWR increased 2,4-D losses by four and 50 times in the first 5-mm outflow compared with the 2,4-D losses with water. After 50-mm outflow, the 2,4-D losses were similar for one core, but in the other core they were still about four times greater with water than with aqueous ethanol. This method to quantify the reduction of the soil's filtering efficiency by SWR is needed for assessing the increased risk of groundwater contamination by solutes exogenously applied to water-repellent soils.
    European Journal of Soil Science 03/2014; 65(3). DOI:10.1111/ejss.12136 · 2.39 Impact Factor
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    ABSTRACT: At 12,900 a BP, the eruption of the Laacher See volcano generated a new parent material forHolocene soil formation in parts of Western Germany. Weathering of these ashes commonly includes the formation of poorly crystalline minerals such as allophane, imogolite and ferrihydrite. Detection of these minerals in soil is difficult, yet an important task, because they may govern soil functions and processes, e.g., stabilisation of organic matter and nutrient availability. Therefore, we characterised three forested Andosols by a combination of wet-chemical and spectroscopic techniques including infrared and (27Al, 29Si) nuclear magnetic resonance (NMR) spectroscopy together with X-ray diffractometry. Deconvoluting the 29Si-NMR spectra revealed that 1.6 to 10.4% of total Si was present as allophanic compounds, which coincided with the amounts of oxalate-extractable Si. Since extraction methods are not completely selective,we observed a slight overestimation of allophanic Si estimated from oxalate extraction. Although the sites under study are located close to each other in similar relief positions and with similar vegetation, the combination of our results revealed varying amounts of loess in the parent materials and varying weathering intensity. High weathering intensities correlate with the amounts of allophane.
    Chemical Geology 01/2014; 363:13-21. DOI:10.1016/j.chemgeo.2013.10.029 · 3.48 Impact Factor
  • Journal of Pesticide Science 01/2014; 39(2):85-90. DOI:10.1584/jpestics.D13-090 · 0.51 Impact Factor
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    ABSTRACT: 1-O-cis-Cinnamoyl-β-d-glucopyranose is known to be one of the most potent allelochemical candidates and was isolated from Spiraea thunbergii Sieb by Hiradate et al. (2004), who suggested that it derived its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. In this study, key structural features and substituent effects of cis-cinnamic acid (cis-CA) on lettuce root growth inhibition was investigated. These structure-activity relationship studies indicated the importance of the spatial relationship of the aromatic ring and carboxylic acid moieties. In this context, conformationally constrained cis-CA analogues, in which the aromatic ring and cis-olefin were connected by a carbon bridge, were designed, synthesized, and evaluated as plant growth inhibitors. The results of the present study demonstrated that the inhibitory activities of the five-membered and six-membered bridged compounds were enhanced, up to 0.27μM, and were ten times higher than cis-CA, while the potency of the other compounds was reduced.
    Phytochemistry 10/2013; DOI:10.1016/j.phytochem.2013.10.001 · 3.35 Impact Factor
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    ABSTRACT: 1-O-cis-Cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure-activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA.
    Phytochemistry 09/2013; 96. DOI:10.1016/j.phytochem.2013.08.013 · 3.35 Impact Factor
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    ABSTRACT: In addition to the 17 essential elements needed for plants to complete their life cycle, the soil contains various non-essential elements, which plants may absorb. Interestingly, some plant species accumulate very high concentrations of non-essential element in their shoots. These species are often called “(hyper) accumulators”. It has been suggested that the distribution of accumulators is phylogenetically determined. Whereas many studies focused on accumulation of various elements in angiosperms, little information about is available for pteridophytes (ferns). Therefore, we performed a comprehensive element analysis in leaves of pteridophytes, and examined their aluminium (Al) accumulation in more detail.
    17th International Plant Nutrition Colloquium, Istanbul, Turkey; 08/2013
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    ABSTRACT: Eucalyptus (Eucalyptus camaldulensis) has relatively high resistance to aluminum (Al) toxicity than the various herbaceous plants and model plant species. To investigate Al-tolerance mechanism, the metabolism of organic acids and the chemical forms of Al in the target site (root tips) in Eucalyptus was investigated. To do this, 2-year old rooted cuttings of E. camaldulensis were cultivated in half-strength Hoagland solution (pH 4.0) containing Al (0, 0.25, 0.5, 1.0, 2.5 and 5.0mM) salts for 5weeks; growth was not affected at concentrations up to 2.5mM even with Al concentration reaching 6000μgg(-1) DW. In roots, the citrate content also increased with increasing Al application. Concurrently, the activities of aconitase and NADP(+)-isocitrate dehydrogenase, which catalyze the decomposition of citrate, decreased. On the other hand, the activity of citrate synthase was not affected at concentrations up to 2.5mM Al. (27)Al-NMR spectroscopic analyses were carried out where it was found that Al-citrate complexes were a major chemical form present in cell sap of root tips. These findings suggested that E. camaldulensis detoxifies Al by forming Al-citrate complexes, and that this is achieved through Al-induced citrate accumulation in root tips via suppression of the citrate decomposition pathway.
    Phytochemistry 07/2013; 94. DOI:10.1016/j.phytochem.2013.06.016 · 3.35 Impact Factor
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    ABSTRACT: Temperature sensitivity of soil organic matter (SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction (LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35 °C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (<1.6 and 1.6-1.8 g cm(-3) ) and bulk soil was measured by solid-state (13) C-NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors controlling long-term decomposition Q10 are more complex due to protective effect of mineral matrix and thus remain as a central question.
    Global Change Biology 04/2013; 19(4):1114-25. DOI:10.1111/gcb.12112 · 8.22 Impact Factor
  • American Journal of Plant Sciences 01/2013; 04(05):1095-1104. DOI:10.4236/ajps.2013.45136
  • Plant Biotechnology 01/2013; 30(5):465-471. DOI:10.5511/plantbiotechnology.13.0718a · 1.06 Impact Factor
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    ABSTRACT: QuestionsWhat is the best way to identify plant indicators for monitoring the responses of semi‐natural grassland communities to various management practices (i.e. burning, burning and mowing, burning and grazing)? Can a multi‐trait plant functional group (PFG) approach extract indicator species more effectively than a single‐trait approach? LocationSemi‐natural and artificial grasslands in the northern and eastern parts of the somma of Mt. Aso, Kumamoto Prefecture, Japan. Methods We analysed a data set from 203 semi‐natural and artificial grassland vegetation plots (each 1 m × 1 m), and compared species and functional compositions among the management types and between the northern and eastern locations using non‐metric multidimensional scaling (NMDS). Potential indicator species were extracted by indicator species analysis (INSPAN) and compared with the results of single‐trait and multi‐trait PFG approaches, which classify plant species into groups based on individual or combinations of traits (growth form, life span, dispersal mode, flowering season and plant height). ResultsOnly the multi‐trait PFG approach successfully clustered the vegetation plots for each management type. Semi‐natural burned‐and‐grazed grasslands in the eastern and northern regions were characterized by a specific PFG among 21 PFGs, whereas the same three PFGs characterized the burned‐and‐mowed semi‐natural grassland of the two regions. The extracted PFGs represent combinations of vegetative, dispersal and reproductive traits (e.g. short, wind‐ and animal‐dispersed species for grazed semi‐natural grasslands; tall, summer‐flowering forbs for mowed semi‐natural grasslands). As compared to indicator species extracted by the multi‐trait PFG approach, INSPAN extracted additional indicator species, but some of these were inappropriate. Conclusions We identified PFGs representing each management type and characterized species adaptations to different disturbance regimes, such as mowing and grazing. Among the species extracted by INSPAN, only those classified into the representative PFGs can serve as indicators for characterizing managed semi‐natural grasslands. Our findings indicate that using a multi‐trait PFG approach can provide reasonable plant indicators for monitoring grassland communities throughout the regions when combined with a species‐based INSPAN approach. This proposed method would contribute to the conservation of plant biodiversity in threatened semi‐natural grazed and mowed grasslands.
    Applied Vegetation Science 01/2013; 16(1):95-109. DOI:10.1111/j.1654-109X.2012.01204.x · 2.42 Impact Factor
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    ABSTRACT: 1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
    Phytochemistry 09/2012; 84. DOI:10.1016/j.phytochem.2012.08.001 · 3.35 Impact Factor

Publication Stats

2k Citations
278.96 Total Impact Points


  • 1998–2015
    • National Institute for Agro-Environmental Sciences in Japan
      • • Biodiversity Division
      • • Environmental Biology Division
      Tsukuba, Ibaraki, Japan
  • 2008–2012
    • The Graduate University for Advanced Studies
      Миура, Kanagawa, Japan
  • 2006
    • Shinshu University
      • Department of Bioscience and Biotechnology
      Matsumoto, Nagano-ken, Japan
  • 2005
    • Yamaguchi University
      Yamaguti, Yamaguchi, Japan