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Plants acquire potassium (K) not only from exchangeable K fractions but also from non-exchangeable K fractions. However, factors affecting the amount of K supplied from the non-exchangeable K fraction have not been well understood. In this study, the effects of soils and exchangeable K on the amount of K supplied to rice from the non-exchangeable K fraction were investigated for six Japanese paddy soils diluted with different rates of quartz sand. The amounts of K supplied from the non-exchangeable K fractions (recharged K) ranged from 14.4 to 137 mg K2O kg−1, equivalent to 10 to 61% of the total K acquired by rice. The amounts of recharged K were affected by the exchangeable K levels in three out of six soils. Although the cultivation experiments were conducted under various K conditions including severe K deficiency, exchangeable K was detected after cultivation in all soils, and the contents of exchangeable K were almost identical for each soil regardless of the dilution ratio of soil with quartz sand. Accordingly, there would be at least three types of non-exchangeable K fractions which dissolve into soil solution to attain a specific level of exchangeable K: (i) a non-exchangeable K fraction that releases K regardless of the exchangeable K level; (ii) a non-exchangeable K fraction that easily releases K with the decrease in exchangeable K under sufficient K conditions without inducing K-deficient symptoms in rice; and (iii) a non-exchangeable K fraction that releases K with the decrease in exchangeable K only under severe K-deficient conditions with accompanying deficient symptoms in rice. The application of K fertilizer would reduce the amount of recharged K acquired by rice from fractions (ii) and (iii), whereas fraction (i) would remain unaffected by the fertilized K until the level of exchangeable K reaches a specific level for each soil. The release of K from a fraction (iii) only occurred under conditions of severe K deficiency; hence, farmers should not rely on this fraction for K supply. [ABSTRACT FROM AUTHOR]

In recent years, computer simulation has been increasingly used to predict changes in actual ecosystems. In these studies, snapshots of ecosystems at certain points in time were instantly constructed without considering their evolutionary histories. However, it may not be possible to correctly predict future events unless their evolutionary processes are considered. In this study, we developed a new ecosystem model for reproducing the evolutionary process on an oceanic island, targeting Nakoudojima Island of the Ogasawara Islands. This model successfully reproduced the primitive ecosystem (the entire island covered with forest) prior to the invasion of alien species. Also, by adding multiple alien species to this ecosystem, we were able to reproduce temporal changes in the ecosystem of Nakoudojima Island after invasion of alien species. Then, we performed simulations in which feral goats were eradicated, as had actually been done on the island; these suggested that after the eradication of feral goats, forests were unlikely to be restored. In the ecosystems in which forests were not restored, arboreous plants with a high growth rate colonized during the early stage of evolution. As arboreous plants with a high growth rate consume a large amount of nutrient in soil, creating an oligotrophic state. As a result, plants cannot grow, and animal species that rely on plants cannot maintain their biomass. Consequently, many animals and plants become extinct as they cannot endure disturbances by alien species, and the ecosystem loses its resilience. Therefore, even if feral goats are eradicated, forests are not restored. Thus, the founder effect from the distant past influences future ecosystem changes. Our findings show that it is useful to consider the evolutionary process of an ecosystem in predicting its future events. [ABSTRACT FROM AUTHOR]

Disturbances caused by invasive ungulates alter soil environments markedly and can prevent ecosystem recovery even after eradication of the ungulates. On oceanic islands, overgrazing and trampling by feral goats has caused vegetation degradation and soil erosion, which can alter soil chemistry. To understand the effects of the changes on plant performance, we conducted a laboratory experiment to assess herbaceous species growth under various soil conditions with phosphorous, nutrients, and acidity. Subsoil was collected from Nakodo-jima in the northwest Pacific. Six herbaceous species dominating the island were grown in soils with three levels of added CaCO3 and P2O5 and two levels of added KNO3. After 4 weeks of growth, the total dry plant weight was significantly lower with no added P2O5, regardless of the addition of KNO3. Three species weighed more under P2O5 and KNO3 addition in high-pH soil, whereas the remaining three weighed less. Our results indicated that herbaceous species growth is limited primarily by phosphorous availability; the limitation is dependent on soil pH, and the trend of dependency differs among species. This implies that ecosystems with extreme disturbances cannot recover without improving the soil chemistry. [ABSTRACT FROM AUTHOR]

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland. [ABSTRACT FROM AUTHOR]

Rice bran contains appreciable amount of phosphorus (P), which can be used as P fertilizers. The efficiency of the P in the rice bran to plants, however, is low, and the fermentation of the rice bran is proposed to improve the P availability for plants. In the present study, 20 kg of rice bran was aerobically fermented by adding 5 kg of rice husk, 0.025 kg of mulch, and 7 L of water and incubating for 35 days with 6 times of stirring, and the changes in the chemical form of P during the fermentation process were investigated by 31P nuclear magnetic resonance spectroscopy and chemical extraction. Most part (84%) of P in the raw rice bran was myo-inositol-1,2,3,4,5,6-hexaphosphate (I6P), which is not available for plants. During the fermentation process, I6P was degraded and transformed into plant-available phosphate anions (orthophosphate). The proportions of the orthophosphate increased to 68% after incubating for 19 days with two times of stirring and 92% after incubating for 35 days with six times of stirring. After the fermentation, the orthophosphate was present as plant available precipitates associated with magnesium and the other monovalent cations. In conclusion, rice bran contains low-available I6P as a major P form, and the fermentation of rice bran accelerates the cleavage of the ester bond of I6P and results in the increased proportion of orthophosphate with high availability to plants. [ABSTRACT FROM AUTHOR]

To clarify the effects of long-term fertilization on the depth profile of plant nutrients and soil acidity in non-allophanic Andosols, a soil survey was conducted on fertilized grassland and adjacent secondary forest in Kuju highland, Oita Prefecture, Japan. Both of the experimental plots had been managed as a semi-natural grassland (managed by cutting, mowing, and burning for raising cows) before mid of the 1960s, and then, the former had been converted into reclaimed grassland with applying agricultural materials such as fertilizers, manure, and lime, and the latter had been abandoned which resulted in secondary succession into the secondary forest. The comparison of the depth profiles between the two plots revealed that the applied Ca2+ and Mg2+ reached at least 100 cm depth of the non-allophanic Andosol profile. The soil pH was increased at least at the depth of 100 cm, and the plant-toxic level of soil acidity (≥12 mmol kg−1), which is one of the characteristic properties of non-allophanic Andosols, was decreased in the fertilized grassland soil. Soil available P was also observed to be increased at least 80 to 100 cm depth, although the mobility was smaller than those of exchangeable cations and soil acidity. Other soil chemical properties, such as cation exchange capacity, total C and N contents, pyrophosphate-extractable Al (Alp) and Fe (Fep), acid-oxalate-extractable Al (Alo), Fe (Feo), and Si (Sio), Alp/Alo ratio, and Alo + 1/2 Feo, were not significantly altered by the modern grassland management activities. This study reveals considerable loss of plant nutrients from the fertilized grassland soil of a non-allophanic Andosol during a half-century. The loss of plant nutrients should be reduced for sustainable agriculture and conserving the natural environment. [ABSTRACT FROM AUTHOR]

Leaf ionome indicates plant phylogenetic evolution and responses to environmental stress, which is a critical influential factor to the structure of species populations in local edaphic sites. However, little is known about leaf ionomic responses of local plant species to natural edaphic mineral variations. In the present study, all plant species and soil samples from a total of 80 soil sites in Shiozuka Highland were collected for multi-elemental analysis. Ioniomic data of species were used for statistical analysis, representing 24 species and 10 families. Specific preferences to ionomic accumulation in plants were obviously affected by the phylogeny, whereas edaphic impacts were also strong but limited within the phylogenetic preset. Correlations among elements resulted from not only elemental synergy and competition but also the adaptive evolution to withstand environmental stresses. Furthermore, ionomic differences of plant families were mainly derived from non-essential elements. The majority of variations in leaf ionome is undoubtedly regulated by evolutionary factors, but externalities, especially environmental stresses also have an important regulating function for landscape formation, determining that the contributions of each factor to ionomic variations of plant species for adaptation to environmental stress provides a new insight for further research on ionomic responses of ecological speciation to environmental perturbations and their corresponding adaptive evolutions. [ABSTRACT FROM AUTHOR]

The article discusses the use of biochar, a carbonated biomass generated through pyrolysis, for improving agricultural productivity and carbon sequestration. The benefits of biochar have been observed in regions such as East and Southeast Asia, where there is a long history of biochar utilization. The article highlights the importance of sharing information on biochar in order to effectively use it in other countries. The special section in the journal Soil Science & Plant Nutrition serves as a starting point for research on biochar utilization for soil sustainability from Asian agronomical and ecological perspectives. [Extracted from the article]

Selective removal of lignin and other recalcitrant compounds, collectively registered as acid-unhyrolyzable residue (AUR), results in bleaching of leaf litter, but the importance of bleaching in decomposition processes on forest soil has not been fully evaluated. The aims of this study were to elucidate the occurrence of bleached area in decomposing leaf litter and to compare chemical composition between bleached and nonbleached portions in a subtropical forest in Japan. Field incubation of leaf litter was performed over an 18-month period with the litterbag method. The decomposition processes during the first 9 month were characterized by the relatively rapid mass loss and increase of bleached area, whereas the mass loss was slowed down and the bleached area decreased thereafter. Mass loss of leaf tissues was faster and AUR content was lower in bleached than in nonbleached portions, indicating the acceleration of mass loss in bleached leaf tissues by the selective decomposition of recalcitrant compounds. The decrease in carbonyl-C in the bleached portions was associated with the increase of extractable nitrogen. The results suggest that the bleaching plays a dominant role in the transformation and turnover of organic compounds and nitrogen in decomposing leaf litter. [ABSTRACT FROM AUTHOR]

Soil erosion after vegetation degradation induced by disturbance by feral goats, an invasive mammal, can lead to loss or accumulation of soil at a local scale and can alter soil chemical properties. This alteration of soil properties can in turn affect the establishment of plant species. We evaluated relationships among the extent of soil erosion, soil chemical properties, and the distribution of plant species in grassland ecosystems after goat eradication on Nakodo‐jima Island in the northwestern Pacific. In 105 1 × 1–m quadrats, changes were measured in the position of topsoil over 2 years. Surface soils were sampled for analysis of chemical properties, and plant species in the quadrat were recorded. Changes in the position of topsoil were related to the area of bare ground. Soil loss occurred at sites where areas of bare ground were extremely large. Significantly higher values of soil exchange acidity and smaller amounts of available phosphorus, total carbon, and total nitrogen were detected in soils at sites with large soil losses. Most of the 11 dominant plant species were absent from sites with large losses of soil. The presence of eight species was significantly negatively related to soil exchange acidity, and three species were significantly positively related to available phosphorus. Our results indicated that exposure of subsoils at the soil surface after vegetation degradation can increase soil loss, which can alter soil chemical properties, and this alteration can continue to limit the establishment of plant species, even long after goat eradication. [ABSTRACT FROM AUTHOR]

Effective conservation of global species diversity requires a clear understanding of spatial scales that support overall diversity across broad scales. Abandonment of semi-natural grasslands has increased their fragmentation and decreased their areal extent. We quantified diversity patterns of plant communities in Japan across hierarchical scales to facilitate the development of an effective nationwide strategy for conserving species diversity in remnant semi-natural grasslands. We applied additive partitioning of plant species diversity, using a nested hierarchical design at three spatial scales (quadrat, grassland, and western and eastern regions of Japan) for three groups of plant species (all species, grassland species and national Red Listed species). We consistently found lower proportions of among-quadrats diversity, and higher proportions of among-grasslands diversity and between-regions diversity in the overall diversity of the entire species complement than would be expected by chance. The high contribution of among-grasslands diversity to overall diversity suggests that each grassland had a unique species content. The second-ranking contributor to overall diversity differed between grassland species and Red Listed species: the second-ranking contributor for grassland species was diversity at the among-quadrats scale but the second-ranking contributor for all species and for Red Listed species was diversity at the between-regions scale. Thus, effective conservation of diversity of the entire species complement in remnant semi-natural grasslands requires preservation of beta diversity in individual grasslands. Our findings highlight the importance of strengthening local preservation and restoration activities within each grassland, and of nationwide strategies for conserving Red Listed species in remnant semi-natural grassland communities. [ABSTRACT FROM AUTHOR]

Soil organic phosphorus (P) is an important P source for biota especially in P-limited forests. Organic P has various chemical formations which differ in bioavailability and these organic P can be degraded by phosphatase enzymes. Here, we report soil P fractions inferred from solution 31P-NMR spectroscopy and soil phosphatase activities of two tropical rain forests on contrasting parent materials; sedimentary and ultramafic igneous (serpentinite) rocks. Compared to the sedimentary soils　and previous studies, P fractions of the serpentinite soils have distinctly high proportions of pyrophosphate and scyllo-inositol hexakisphosphate (scyllo-IP6). The accumulation of pyrophosphate and scyllo-IP6 may be related to strong sorptive capacity of iron oxides present in the serpentinite soils, which implies a consequent low P availability in the serpentinite soils. Mean value of soil phosphatase activities was higher in the serpentinite soils than in the sedimentary soils, suggesting that biota in these serpentinite forests depend more on soil organic P as a P source. [ABSTRACT FROM AUTHOR]

Tricholoma matsutake, a basidiomycete, forms ectomycorrhizas withPinus densifloraas the host tree. Its fruiting body, “matsutake” in Japanese, is an edible and highly prized mushroom, and it grows in a circle called a fairy ring. Beneath the fairy ring ofT. matsutake, a whitish mycelium-soil aggregated zone, called “shiro” in Japanese, develops. The front of the shiro, an active mycorrhizal zone, functions to gather nutrients from the soil and roots to nourish the fairy ring. Bacteria and sporulating fungi decrease from the shiro front, whereas they increase inside and outside the shiro front. Ohara demonstrated that the shiro front exhibited antimicrobial activity, but the antimicrobial substance has remained unidentified for 50 years. We have identified the antimicrobial substance as the (oxalato)aluminate complex, known as a reaction product of oxalic acid and aluminum phosphate to release soluble phosphorus. The complex protects the shiro from micro-organisms, and contributes to its development. “Antimicrobial activity of the matsutake shiro” for left figure.“The antimicrobial substance, the (oxalato)aluminate complex, from the matsutake shiro” for right figure. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

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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 13C- 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. [ABSTRACT FROM AUTHOR]

Carbon dynamics during litter decomposition have been described in a variety of forest ecosystems and provided insights into carbon flow in soils. To quantitatively assess how decomposition processes vary between litter types, solid-state C cross-polarization and magic-angle spinning nuclear magnetic resonance (CPMAS NMR) technique was applied to analyze conifer (cedar, cypress) and hardwood (chinquapin, beech, oak, birch) litter which had degraded during a 3 year litterbag experiment throughout Japan. The results were used to identify compositional changes and estimate decomposition constants ( k values) in exponential equations. Total litter and carbon type mass losses during decomposition varied significantly between litter types, being affected by the initial physicochemical litter quality. Concomitant increases and decreases in carbonyl and O/N-alkyl C compositions, respectively, were observed for all litter types, but aromatic and aliphatic C dynamics were less consistent. In hardwoods, [aromatic/aliphatic C ratio] was generally stable during decomposition, suggesting that, in hardwoods, the decomposabilities of aromatic and aliphatic C were similar. In the conifers, an increasing [aromatic/aliphatic C ratio] during decomposition suggested that aromatic C was more recalcitrant than aliphatic C. These results suggest that different decomposition processes between litter types might be related to different aromatic and aliphatic C behaviors, as affected by lignin stability and lipid leachability and biosynthesis. Variations in the k values for total litter and carbon types were not obvious between litter types, although the mass loss patterns differed significantly. The k values estimated in this study may contribute to predictions of soil carbon dynamics and the validation of carbon compartment models in forest ecosystems. [ABSTRACT FROM AUTHOR]

Sorghum accumulates sugars (sucrose, glucose and fructose) in the stem after anthesis. Brix is commonly used to indicate total sugar content; however, the relationship between Brix and specific sugar components has not been sufficiently investigated in sorghum juice in Japan. In this study, we measured the sugar components of sorghum juices from 109 varieties using capillary electrophoresis, which can quantify each sugar component in crude juice without further purification. The results indicated that the Brix of sorghum juice was proportional to the total sugar and sucrose concentrations ( r = 0.900 and r = 0.894, P < 0.01, respectively). Glucose concentration had a significant positive correlation with fructose concentration ( r = 0.964, P < 0.01), but no correlation was detected between Brix and the two hexose sugars, glucose and fructose. Our results showed that sucrose comprised approximately 75% of the total sugar in varieties with Brix values greater than 15. These findings may be applied in sorghum breeding efforts to develop varieties that accumulate high levels of sugars in the juicy stems of sorghum plants. [ABSTRACT FROM AUTHOR]

Questions What 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? Location Semi-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). Results Only 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. [ABSTRACT FROM AUTHOR]

Physiological and biochemical studies on the leaf apoplast have been facilitated by the use of the infiltration–centrifugation technique to collect intercellular washing fluid (IWF). However, this technique has been difficult to implement in rice (Oryza sativa L.) for various reasons. We compared the collection efficiency of leaf IWF between two types of rice varieties (Indica and Japonica), as well as between rice and other species (spinach, snap bean and wheat). Although the extraction of IWF in most species took only 2–3 min, it took up to 35 min in rice. The difficulty in infiltration with rice was ascribed to the small stomatal aperture and hydrophobicity of the leaves. In this study, we have established an improved method for collecting IWF and determining the apoplastic air and water volumes in rice leaves. We have shortened the infiltration time to 8 min via the following improvements: (i) infiltration under outdoor shade in the daytime to prevent stomatal closure and a rise in temperature of the infiltration medium; (ii) soaking of leaves in a surfactant solution to decrease the leaf hydrophobicity; and (iii) continuous pressurization using a sealant injector to facilitate the infiltration. The rapid collection of IWF achieved using this technique will facilitate study of the leaf apoplast in rice. [ABSTRACT FROM AUTHOR]

Mealybugs, which include several agricultural pests, are small sap feeders covered with a powdery wax. They exhibit clear sexual dimorphism; males are winged but fragile and short lived, whereas females are windless and less mobile. Thus, sex pheromones emitted by females facilitate copulation and reproduction by serving as a key navigation tool for males. Although the structures of the hitherto known mealybug pheromones vary among species, they have a common structural motif; they are carboxylic esters of monoterpene alcohols with irregular non-head-to-tail linkages. However, in the present study, we isolated from the Matsumoto mealybug, Crisicoccus matsumotoi (Siraiwa), a pheromone with a completely different structure. Using gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy, we identified the pheromone as 3-methyl-3-butenyl 5-methylhexanoate. Its attractiveness to males was confirmed in a series of field trapping experiments involving comparison between the isolated natural product and a synthetic sample. This is the first report of a hemiterpene mealybug pheromone. In addition, the acid moiety (5-methylhexanoate) appears to be rare in insect pheromones. [ABSTRACT FROM AUTHOR]

We investigated 10 soils from six states in the United States to determine the relationship between potentio-metric titration derived soil surface charge and the concentration of water-extractable P (WEP). Phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy was used to determine the chemical speciation of soil P. The surface charge value at the native soil pH was correlated to the WEP concentration, indicating that electrostatic interactions are involved in determining soil phosphate solubility. The titration curves were fit to a two-site Langmuir model and analysis showed that the native pH surface charge was accounted for by the low pH Type Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. site, attributed to positively charged metal (oxy)hydroxides. The 31P NMR data indicated that 98% of the inorganic form of P was composed of orthophosphate species and 95% of the organic P was composed of the P monoester class compounds. The inorganic orthophosphate form of P was directly related to the total soil P content, suggesting that external fertilizer inputs control the level of this form of soil P. In contrast, P monoester class compound content was not related to total soil P content, suggesting that organic soil P is controlled by P cycling independent of external P inputs. The 31P NMR speciation data indicated that the inorganic orthophosphate, pyrophosphate, and DNA P concentrations in the soils were significantly associated with oxalate-extractable AI and Fe concentrations, which further demonstrates that metal (oxy)hydroxides are important surfaces where P species are interacting with soils. [ABSTRACT FROM AUTHOR]

Velvetbean ( Mucuna pruriens) plants impede the growth of neighboring plants. One compound, 3-(3′,4′-dihydroxyphenyl)- l-alanine ( l-DOPA), is responsible for the allelopathic capacity of velvetbean. This compound is an active allelochemical that decreases root growth of several plant species. In mammals, l-DOPA is a well-known therapeutic agent for the symptomatic relief of Parkinson's disease. However, its mode of action in plants is still not well understood. To address such issues, gene expression in Arabidopsis thaliana plants, which had been exposed to l-DOPA, was analyzed using DNA microarrays. After 6 h of l-DOPA exposure, the expression of 110 genes was significantly upregulated, and the expression of 69 genes was significantly downregulated. These induced genes can be divided into different functional categories, mainly on the basis of subcellular localization, metabolism, and proteins with a binding function or cofactor requirement. Based on these results, we suggest that l-DOPA acts by two mechanisms: it influences amino acid metabolism and deregulates metal homeostasis, especially that of iron, which is required for the fundamental biological processes of all organisms. [ABSTRACT FROM AUTHOR]

In this study, we discovered and isolated an attractant for a mealybug-parasitic wasp Anagyrus sawadai from an esterification product prepared with commercialized lavandulol (2-isopropenyl-5-methyl-4-hexen-1-ol) and butyryl chloride. Using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy, we determined the structure of the compound to be (2,4,4-trimethyl-2-cyclohexenyl)methyl butyrate (cyclolavandulyl butyrate). This is a novel compound as far as we know, although the alcohol moiety has been known as a cyclization product from lavandulol. Cyclolavandulyl butyrate has two enantiomers, and the (−)-isomer, which is suggested to have S configuration, showed higher attractiveness. A potential use for the A. sawadai attractant for mealybug management in agricultural fields is discussed. [ABSTRACT FROM AUTHOR]

The mycotoxin deoxynivalenol (DON) causes serious problems worldwide in the production of crops such as wheat and barley because of its toxicity toward humans and livestock. A bacterial culture capable of degrading DON was obtained from soil samples collected in wheat fields using an enrichment culture procedure. The isolated bacterium, designated strain WSN05-2, completely removed 1,000 μg/mL of DON from the culture medium after incubation for 10 days. On the basis of phylogenetic studies, WSN05-2 was classified as a bacterium belonging to the genus Nocardioides. WSN05-2 showed significant growth in culture medium with DON as the sole carbon source. High-performance liquid chromatography analysis indicated the presence of a major initial metabolite of DON in the culture supernatant. The metabolite was identified as 3- epi-deoxynivalenol (3- epi-DON) by mass spectrometry and H and C nuclear magnetic resonance analysis. The amount of DON on wheat grain was reduced by about 90% at 7 days after inoculation with WSN05-2. This is the first report of a Nocardioides sp. strain able to degrade DON and of the yet unknown 3- epi-DON as an intermediate in the degradation of DON by a microorganism. [ABSTRACT FROM AUTHOR]

We quantitatively clarified the early humification processes on Japanese cedar and Hinoki cypress forest floors by using a litterbag experiment and the solid-state C CPMAS NMR technique. There was no significant effect on litter mass loss during early humification between both coniferous litters regardless of the shape of their needles. Carbon composition in both litters showed similar trends during early humification. A/ O-A as a humification index was low, around 0.6, in both litters throughout the experiment period although 60% of litter mass was lost. Coniferous litter incubated for 3 years might not be well-humified and would be susceptible to physical fragmentation. Carbon mass loss rates in conifers were in the following order: O-alkyl > aliphatic > aromatic > carbonyl carbons, differing with hardwoods. Conifers had concomitantly higher and lower mass loss rates of aliphatic and aromatic carbons than hardwoods. Soil organic carbon (SOC) accumulated in topsoil for conifers had relatively high and low contents of aliphatic and aromatic carbons than that for hardwood. These compositional differences of SOC among forests could be caused by the high and low supply rates of aliphatic and aromatic carbons from litter to topsoil. Consequently, initial litter nature and humification processes can affect the compositional qualities of SOC accumulated in soil. [ABSTRACT FROM AUTHOR]

The 13C labels of [13C]carbon dioxide and D-[13C6]glucose were incorporated into cyanamide (NH2CN) when they were administered to Vicia villosa subsp. varia shoots. In contrast, the administration of sodium [2,3-13C2]pyruvate did not affect the relative area of the [M + 1]+ ion of cyanamide in the gas chromatography-mass spectrometry analysis. [2,3-13C2]Pyruvate was incorporated into organic acids that are part of the citric acid cycle, such as succinate and fumarate, confirming that the shoots absorbed and metabolised it. These observations demonstrated that the carbon atom of cyanamide is derived from any of the carbohydrates that are present upstream of pyruvate in the metabolic pathway. [ABSTRACT FROM AUTHOR]

The methanol extract of Bletilla striata, an ornamental orchid in eastern Asia, exhibited plant growth-inhibitory activity. It was purified by continuous chromatography, based on the inhibitory activity against the growth of lettuce seedlings, resulting in two glycosidic compounds, militarine and dactylorhin A. The EC50 values of militarine and dactylorhin A against the radicle elongation of the lettuce seedlings were 0.28 and 0.88 mmol L−1, respectively. The amount of militarine and dactylorhin A in the methanol extract of the aerial part of B. striata was calculated to be 5.6 and 7.5 mg g−1 fresh weight, respectively. The inhibitory activity of militarine and its content in the methanol extract revealed that the plant growth-inhibitory activity of the extract of B. striata was mainly related to militarine. The inhibitory activity of militarine against the growth of Italian ryegrass and timothy were of the same level as that of lettuce. [ABSTRACT FROM AUTHOR]

We isolated an antimicrobial compound from the aerial tissue of Geranium carolinianum and identified it as ethyl 3, 4, 5-trihydroxy benzoate (ethyl gallate) by 1H-NMR and 13C-NMR and gas chromatography–mass spectrometry. The antimicrobial activity of ethyl gallate against three potato pathogens was assayed by the paper disk method. The activity against Ralstonia solanacerum, Streptomyces scabies, and Streptomyces acidiscabies was observed at concentrations >200, >300, and >300 µg disk−1, respectively. These results suggest that the antimicrobial activity of Geranium carolinianum against soil-borne plant disease pathogens is partly related to ethyl gallate. [ABSTRACT FROM AUTHOR]

Natural cyanamide (NH2CN) has recently been found in three Leguminosae plants: Vicia villosa subsp. varia, Vicia cracca and Robinia pseudo-acacia. As cyanamide has long been thought to be absent in nature, its physiological role and biosynthesis are totally unknown. In the present study, we demonstrated the incorporation of 15N from [15N]nitrate and [15N]ammonium into cyanamide using shoots of V. villosa subsp. varia, which ruled out the possibility that nodules are essential in cyanamide biosynthesis. We also applied [15N2]cyanamide to shoots of V. villosa subsp. varia to monitor its turnover, and detected [15N2]cyanamide in the leaves within 4 h; it was present without detectable degradation for more than 4 days. In contrast, maximum incorporation of 15N into cyanamide molecules was observed after 4 days of feeding the shoots with 15N-labeled inorganic ions andl-[amide-15N]-glutamine, indicating that these nitrogenous compounds are distant precursors of cyanamide. Although the guanidino group ofl-arginine (-NH-C(NH2)=NH) and urea (NH2C(=O)NH2) were candidate precursors of cyanamide on the basis of structural similarity, direct incorporation of the guanidino group ofl-[13C6,15N4]-arginine and [13C,15N2]urea into cyanamide was not observed. These results eliminated the possibility that cyanamide is biosynthesized by the addition of ammonia to an electrophilic carbon or by the conversion of the tested compounds that were structurally relevant to cyanamide. [ABSTRACT FROM AUTHOR]

A new scheme for fine fractionating and purifying a crude fulvic acid fraction was proposed. The fractionation procedure includes an adsorption process of the fulvic acid fraction on a hydrophobic resin (e.g. XAD-8 and DAX-8) and a sequence of successive elution processes. This procedure yields a non-adsorbed fraction (FA-1), a 0.1 mol L−1 HCl eluted fraction (FA-2), a distilled water eluted fraction (FA-3) and a 0.1 mol L−1 NaOH eluted fraction (FA-4). To remove salts and water, the fractionated organic molecules were co-precipitated with Al hydroxides at pH 5 and collected by centrifugation. Recoveries of carbon from the crude fulvic acid fraction of an Andosol were 42, 20, 19 and 14% for FA-1, FA-2, FA-3 and FA-4, respectively, and 96% of carbon was recovered in total. Optical properties and 13C nuclear magnetic resonance spectra indicated that the chemical properties of FA-1 were similar to those of FA-2 and were hydrophilic, while the chemical properties of FA-3 were very close to those of FA-4 and were hydrophobic (estimated hydrophobicity: humic acid >> FA-4 ≥ FA-3 >> FA-2 ≥ FA-1). A fulvic acid that can be isolated using the International Humic Substances Society method would be, in practice, a mixture of hydrophilic fulvic acid (FA-2) and hydrophobic fulvic acid (FA-3 + FA-4). The method developed in the present study will provide more detailed, quantitative and complete information of the fulvic acid fraction of soils. [ABSTRACT FROM AUTHOR]

Aluminum (Al)–humus complexes are abundant in the A horizons of non-allophanic Andosols and contribute to the unique properties of volcanic ash soils, such as high reactivity with phosphate ions and a low bulk density. Natural non-allophanic Andosols commonly show Al toxicity to plant roots. There have been very few studies examining the contribution of Al–humus complexes to the Al toxicity of plant roots, although the complexes are the probable source of the toxic Al. We extracted humic substances from the A horizon of a non-allophanic Andosol using NaOH solution and reacted the humic substances and partially neutralized the AlCl3 solution at three pH conditions (pH 4.0, 4.5 and 5.5) to prepare pure Al–humic substance complexes. The Al solubility study (equilibrium study in 10−2 mol L−1 CaCl2) and the Al release study (a stirred-flow method using 10−3 mol L−1 acetate buffer solution adjusted to pH 3.5) indicated that all the synthetic complexes easily and rapidly release monomeric Al into the liquid phase with slight changes in pH and ion strength, although the Al contents and their extent of polymerization are considerably different among the complexes. A plant growth test was conducted using a medium containing the Al–humic substance complexes and perlite mixture. Root growth in burdock ( Arctium lappa) and barley ( Hordeum vulgare L.) was reduced equally by all three complex media, and the roots showed the typical injury symptoms of Al toxicity. These results indicate that in soils dominated by Al–humus complexes the Al released from the Al–humus complexes, as well as the exchangeable Al adsorbed by soil minerals, is definitely toxic to plant roots. [ABSTRACT FROM AUTHOR]

14C ages and δ13C were examined for sclerotium grains to elucidate the characteristics of these grains distributed in forest soils. The ages of the grains from surface A horizons and buried A horizons were ca 100–200 bp and ca 300–1,200 bp, respectively. In comparison with humic acid extracts, the 14C ages were in the increasing order: humic acid fraction < humic acid Pg fraction < sclerotium grains. The δ13C values for sclerotium grains in surface A horizons and buried A horizons were approximately −31‰ to −28‰, and these values were approximately 2–4‰ smaller than those of humic acids and soils. The C content of the grains had a tendency to decrease with increasing 14C ages, while the C content of humic acid was constant with age. The 14C ages of sclerotium grains indicate the individual age of grain formation, which are more likely to assign closer ages to the beginning of soil forming than the 14C ages of humic acid. The low δ13C values for sclerotium grains have presumably originated from characteristically biological organics, which may be protected from attack in soils because of their structure. [ABSTRACT FROM AUTHOR]

The article offers a study on the decomposition of methylthio-s-triazine herbicides by Rhodococcus sp. strain FJ1117YT as well as the production of methylsulfinyl, methylsulfonyl and hydroxy analogs. It attempts to form the biodegradatioon of pathway of simetryn through the separation of the methylsulfonyl analog and the hydroxy analog by liquid chromatography-mass spectrometry (LC-MS) and/or nuclear magnetic resonance (NMR) analysis. Results highlight the oxidization and hydrolization of the methylthio group by the strain FJ1117YT. Apart from methylthio-s-triazines, the strain also metabolizes ametryn, desmetryn, dimethametryn, and prometryn. The authors stress the need for further study on the biodegrading function of the strain in agricultural environment.

Lycoris radiata Herb., a common medicinal plant of Far East Asia, was examined for its potential use in paddy weed control. The preliminary screening in greenhouse conditions indicated growth inhibitory activities. The emergence, root and shoot growth, and root dry weight of the bioassay species were reduced when grown in soil mixed with the leaves of L. radiata. Aqueous extracts of the fresh leaves at various concentrations inhibited the root and shoot growth of all tested plant species. To identify the active components, L. radiata ethanolic extract was subjected to bioassay-guided fractionation, purification, and spectroscopic analysis. This process led to the isolation of lycorine as a potential allelochemical. The concentration of lycorine in the dry leaves of L. radiata is estimated to be 0.08%. It is possible that lycorine is exuded from the roots or leaches from the living or decomposing leaves, along with other numerous inhibitors, and inhibits the growth of neighboring or successional plants. These results suggest that L. radiata has the potential to inhibit plant growth and lycorine acts as one of the most important plant growth inhibitors. This plant can be grown as a ground cover plant and its dead leaves could be applied as cover mulch. [ABSTRACT FROM AUTHOR]

Cyanamide (NH 2 CN) has recently been isolated as a plant growth inhibitor from Vicia villosa , which is the first discovery of cyanamide from natural sources. To reveal the presence of the biosynthesized cyanamide in plants, 3.4&ThickSpace;mM potassium ( 15 N)nitrate was administered to 15- to 35-day-old plants of V. villosa , from which the cyanamide was purified and subjected to GC/MS analysis. The isotopic ratio 15 N/( 14 N&ThickSpace;+&ThickSpace; 15 N) of the cyanamide was calculated to be 0.143, while that of the cyanamide extracted from V. villosa grown in the presence of a natural N source was 0.0065. The 15 N-enrichment proved de novo biosynthesis of cyanamide. [ABSTRACT FROM AUTHOR]

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Focuses on sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker). Discovery of two distinct electroantennographycally active components, A and B, and a weakly active component C in a solvent extract from virgin females of the Ishigaki strain of the tussock moth; Finding of components A, B, and C in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively; Confirmation that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1; Discussion of the attractiveness of the components to the males on both Japanese islands in the context of the activity and possible evolution of pheromonal polymorphism in the species.

We investigated the influences of humic acid on the removal of Al tridecamer (Al13) from a hydroxyaluminum (HyA) solution at various humic acid/Al ratios. The Al species contained in the solution were analyzed by using a liquid-state 27Al-NMR and an atomic absorption spectrometer and fractionated into three Al species: (i) Al13, (ii) Al monomer and dimer (AlSYM), and (iii) other undefined species including aggregated/precipitated Al (AlNON). By the addition of humic acid to the HyA solution, the concentration of Al13 was rapidly decreased within 0.007 d (10 mm). The decrease in Al13 and the increase in AlNON were more pronounced at a higher humic acid/Al ratio. When the molar ratio of humic acid carboxylic groups to Al exceeded 0.8, Al-3 was undetected from solution within 0.007 d. The formation of Al13-humic acid complexes and the aggregation/precipitation of those complexes were a predominant mechanism in removing aqueous Al13 at the early stage of the reaction. Approximately 10 mol of carboxylic groups in humic acid were required to remove 1 mol of Al13 from the HyA solution. Aqueous AID had greater preference in precipitating with humic acid than AlSYM. After 5 to 570 d of aging, the concentration of Al13 and AlNON also decreased and increased, respectively, both in the presence and absence of humic acid. In conclusion, aqueous Al13 would not exist in soil solution under a high humic acid condition. [ABSTRACT FROM AUTHOR]

In order to elucidate the allelopathic effect of leaf litter leachates under laboratory conditions, a modified ‘sandwich method’, which places leaves between two layers of agar, was used. Fifty mg of leaves was used per 10 cm2 cell. Agar concentrations at 0.5–1.0% were the best for gel support in determining radicle and hypocotyl elongation of lettuce. The optimum incubation time for bioassay was three days after imbibition onset. Among 20 typical tree species in Asia, Cymbopogon citratus and Derris scandens showed the strongest inhibitory activity determined by the sandwich method, followed by Piper betle, Tamarindus indica, and Gliricidia sepium. This bioassay seems to be a reliable method for screening allelopathic activity from leaf litter leachates. [ABSTRACT FROM AUTHOR]

A sex pheromone component of Pseudococcus cryptus has been isolated and identified. The crude pheromone extract obtained by airborne collection was fractionated by liquid chromatography (LC) on Florisil, and further purified by high performance liquid chromatography and preparative Gas Chromatography (GC). The pheromone component was shown to be an ester, the alcohol part of which was identical to the known alcohol moiety of the pheromone of Planococcus citri. The chemical structure was determined to be 3-isopropenyl-2,2-dimethylcyclobutylmethyl 3-methyl-3-butenoate by MS and `H NIMR analyses. The absolute configuration of the pheromone was assigned as (IR,3R) by comparison of the retention lime of the alcohol derived from the P. cryptus pheromone with those of the alcohol derived from P. citri pheromone, and a synthetic sample of alcohol enriched in the (1 R,3R)-enantiomer, using a chiral GC stationary phase. The structure of the pheromone was confirmed by synthesis, and by bioassays in a glasshouse. [ABSTRACT FROM AUTHOR]

Cyanamide was isolated from the leaves and stems of hairy vetch (Vicia villosa), guided by plant growth inhibitory activity against lettuce (Lectuca sativa) seedlings. A large proportion of the inhibitory activity in the crude extract was explained by the presence of cyanamide, suggesting it to be a possible allelochemical in this species. The amount in a 9-day-old seedling, which had been grown without nutrients, reached approx. 40 times that of a nongerminated seed, demonstrating cyanamide biosynthesis in the seedlings. This is the first report on the isolation of a possible allelochemical from hairy vetch and also of the finding of cyanamide as a natural product. [ABSTRACT FROM AUTHOR]

L-Canavanine is a nonprotein amino acid contained in jack bean [Canavalia ensiformis (L.) DC] and shows a plant inhibitory effect. The inhibitory effect was determined by an immersion test and a microdrop test that employed rice seedlings. L-Canavanine inhibited elongation of the second leaf sheath of rice seedlings more than other natural bioactive substances, such as salicylic acid and cinnamic acid. The modified microdrop test revealed that the mode of action of L-canavanine had no relation to gibberellin synthesis. In the microdrop test, the inhibitory effect of L-canavanine was decreased by simultaneous addition of L-arginine, an analog of L-canavanine. Free amino acid analysis of rice shoots clearly showed that L-canavanine induced an unusual accumulation of L-arginine. However, accumulation of L-arginine did not cause the inhibitory effect on plant growth. These results suggest that the mechanism of inhibition of L-canavanine is closely related to the inhibition of arginine metabolism. [ABSTRACT FROM AUTHOR]

The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl3 than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AlCl3 solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La3+ competes for the binding sites for Al3+ on the plasma membrane. The form of Al in the xylem sap was identified by 27Al-nuclear magnetic resonance analysis. The chemical shift of 27Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem. [ABSTRACT FROM AUTHOR]

Presents a study which investigated aluminum speciation in aluminum-silica solutions and potassium chloride extracts of acidic soils. Methodology employed to differentiate chemical species of Al in soil solutions; Utilization of nuclear magnetic resonance (NMR) technique to conduct study; How NMR was applied; Findings of study.