Limestone Soils Research Articles

Variation of Leaf Carbon Isotope in Plants in Different Lithological Habitats in a Karst Area

Drought is the major factor that limits vegetation recovery in rocky desertification areas. The leaf carbon isotope (δ13C) value is related to plant water-use efficiency (WUE) and is of great significance in revealing the WUE characteristics of species in karst areas. Measurements of the δ13C value in plant leaves and the nutrient and water contents of lithologic soils were obtained for six woody species (cypress, Cupressus funebris Endl.; mansur shrub, Coriaria nepalensis Wall.; camphor, Cinnamomum bodinieri Levl.; birch, Betula luminifera H. Winkl.; alder, Alnus cremastogyne Burk. and dyetree, Platycarya longipes Wu.) planted in three different lithologic soil types (dolomite, dolomite sandstone, limestone) in the karst area of Guizhou Province. The results showed that C. funebris in the dolomite sandstone soil had the highest δ13C value (−27.19‰), whereas C. bodinieri in the limestone soil had the lowest δ13C value (−31.50‰). In terms of lithology, the average leaf δ13C values were −28.66‰ (dolomitic sandstone), −28.83‰ (dolomite), and −29.46‰ (limestone). The δ13C values of C. funebris and A. cremastogyne were significantly lower in the limestone soil than in the dolomite and dolomite sandstone soil, indicating that the WUE of some tree species is affected by soil conditions under different lithological development processes. Moreover, the relationship between the δ13C value in the leaves and the comprehensive soil conditions varied among the species, and the δ13C value was negatively correlated with the soil water content in all three soil types. Our study provides basic data on the composition characteristics of the δ13C value of tree species, which is beneficial for the selection of tree species for vegetation restoration and afforestation in karst areas.

Urbanization-induced acid rain causes leaching loss of calcium from limestone-derived soil in South China

Acid rain events in Yuebei, a region of northern Guangdong Province, China, have been increasing due to rapid urbanization in recent years. A three-year study was conducted to assess the effect of rainfall on losses of dissolved calcium (Ca2+) from limestone soils in a karst area in Yuebei. Soil leachate was collected from 61 events that produced more than 100 ml leachate per event during a 3-year period. Each rainfall event caused on average a loss of 8.5 × 10−4 g Ca2+ kg−1 soil with a Ca2+ loss of 2.16 × 10−5 g kg−1 per mm of rain. Cumulative net Ca2+ loss from the soil for the 61 events monitored was 0.05 g kg−1. In terms of Ca-loss per mm rain, the largest net Ca2+ loss from the soil occurred with mild acid rain (pH 4.5–5.6), followed by non-acid rain (pH 5.6–6.29) and severe acid rain (pH < 4.5). Net Ca2+ losses through natural rainfall were significantly larger than those induced by simulated rainfall with distilled water (control) or rainwater from the karst depression area of an adjacent talus slope. Total water soluble Ca2+ content in the soil continuously decreased due to acid rain, with a total reduction of 0.36 g kg−1 during the three-year experimental period. Net Ca2+ losses from the soil were positively correlated with leachate Ca2+ concentration and rainfall and negatively correlated with rainwater pH. The losses of Ca2+ from the soil can increase the risk of acidifying soils in the flat karst area in Yuebei, which may also affect the adjacent regions through changing the chemistry of groundwater and surface water.

Effect of Soil Moisture and Temperature on the Soil Inorganic Carbon Release of Brown Limestone Soil in the Karst Region of Southwestern China

In order to understand the influence of environmental factors on the carbonate conversion of the Karst soil, typical brown limestone and red soil samples were collected from the Karst ecosystem, and a 100-day incubation experiment was conducted. The characteristics of inorganic carbon release from the soil under three temperature gradients (15, 25, and 35℃) and water contents (30%, 65%, and 100% WHC) were studied by adding 14C-CaCO3 for 100 d. The results showed that under the different soil moisture and temperature conditions, the maximum rate and the cumulative amount of inorganic carbon release from the soil over 100 days varied between 0.7-16.8 mg·(kg·d)-1and 5.9-29.4 mg·kg-1, respectively, in the brown limestone soil, and varied between 39.7-103.3 mg·(kg·d)-1 and 83.3-135.1 mg·kg-1, respectively in the red soil. Under drought conditions (30% WHC), the cumulative amount of inorganic carbon release was the highest for the two soils and increased with increasing temperature. At 65% WHC and 100% WHC, increasing temperature can still promote inorganic carbon release from the soil. The temperature sensitivity of the soil inorganic carbon release in the brown limestone soil is greater than that of the red soil, which is significantly affected by soil moisture. The soil pH and MBC content were remarkably increased after adding CaCO3, and the difference between the two soils was significant. The variance partition showed that temperature and soil moisture can explain 7.6% and 2.0% of the soil inorganic carbon release variability, respectively. In conclusion, warming and drought aggravate inorganic carbon release from brown limestone soil in the southwestern Karst region. Therefore, in the context of global warming and more frequent extreme precipitation events, the effects of soil moisture and temperature on inorganic carbon conversion in soil should be fully considered when studying the soil carbon cycle and its dynamic changes in southwestern Karst. This research can provide a scientific basis for further understanding the influence of climate change on the global carbon cycle.

Deprivation of root-derived resources affects microbial biomass but not community structure in litter and soil.

The input of plant leaf litter has been assumed to be the most important resource for soil organisms of forest ecosystems, but there is increasing evidence that root-derived resources may be more important. By trenching roots of trees in deciduous and coniferous forests, we cut-off the input of root-derived resources and investigated the response of microorganisms using substrate-induced respiration and phospholipid fatty acid (PLFA) analysis. After one and three years, root trenching strongly decreased microbial biomass and concentrations of PLFAs by about 20%, but the microbial community structure was little affected and the effects were similar in deciduous and coniferous forests. However, the reduction in microbial biomass varied between regions and was more pronounced in forests on limestone soils (Hainich) than in those on sandy soils (Schorfheide). Trenching also reduced microbial biomass in the litter layer but only in the Hainich after one year, whereas fungal and bacterial marker PLFAs as well as the fungal-to-plant marker ratio in litter were reduced in the Schorfheide both after one and three years. The pronounced differences between forests of the two regions suggest that root-derived resources are more important in fueling soil microorganisms of base-rich forests characterized by mull humus than in forests poor in base cations characterized by moder soils. The reduction in microbial biomass and changes in microbial community characteristics in the litter layer suggests that litter microorganisms do not exclusively rely on resources from decomposing litter but also from roots, i.e. from resources based on labile recently fixed carbon. Our results suggest that both bacteria and fungi heavily depend on root-derived resources with both suffering to a similar extent to deprivation of these resources. Further, the results indicate that the community structure of microorganisms is remarkably resistant to changes in resource supply and adapts quickly to new conditions irrespective of tree species composition and forest management.

Capsaicinoids in Chili Habanero by Flow Injection with Coulometric Array Detection

AbstractThis study presents a sensitive electroanalytical method for the determination of capsaicinoids in chili extracts using flow injection with coulometric array detector. Flow injection method was developed based on the coulometric signal of capsaicinoids obtained by high performance liquid chromatography with coulometric detector (HPLC‐ECD). Capsaicinoids concentration in 18 chili samples from Yucatán México cultivated in different types of soils was quantified using UHPLC‐DAD and HPLC‐ECD and expressed in Scoville units. The plants were cultivated in a greenhouse on three types of limestone soils, namely, red, black and brown. Chili peppers were harvested in two stages of maturity: immature (green), and mature (orange). HPLC‐ECD method showed ten times higher sensitivity compared to the UHPLC‐DAD. Capsaicinoid content in 18 chili samples was measured by flow injection method. The best correlation with the Scoville units was obtained by the analysis of the current signal of the sensor poised at +450 mV (R2=94). ANOVA analysis showed that the soil type and the harvest date were significant for the capsaicinoid content. Chili plants cultivated in red soil had higher capsaicinoid content. In addition, the capsaicinoid content was increasing at later harvest dates. In summary, the suggested flow injection method with coulometric array detector decreased the time of analysis from 15 min to 30 s. Therefore it can be successfully applied for the routine capsaicinoid analysis in chili.

Dynamics of soil gross nitrogen transformations during post-agricultural succession in a subtropical karst region

Gross nitrogen (N) transformations are crucial in determining soil N status, but how gross N transformations change during post-agricultural succession remains poorly understood. Here, gross N transformations were measured using a 15N isotope dilution technique in a subtropical karst region, southwest China. A stratified random sampling scheme was adopted and the succession sequence included grassland (~4 years), shrubland (~15 years) and secondary forest (~30 years) with cropland as reference. The soil was leptosols (limestone soil). Soil total N concentrations were significantly (P < 0.05 hereafter) elevated in the shrubland and forest relative to the cropland and grassland. No clear pattern was found for NH4+ concentration, but NO3− concentration increased from the grassland to the forest. The gross rates of N mineralization and nitrification (GN) were significantly lower in the grassland than in the cropland, but increased significantly during post-agricultural succession. There were no clear patterns for the rates of dissimilatory NO3− reduction to NH4+ and gross NO3− immobilization. Gross NH4+ immobilization (GAI) in the forest was lowest but there was no significant difference among the cropland, grassland and shrubland. Gross N mineralization rate correlated significantly with protease activity, implying that the depolymerization of N-containing polymers was likely the rate-limiting step of gross N mineralization. Net nitrate production rate and GN:GAI ratio increased significantly from the grassland to the forest, supporting that soil N cycling likely became more open during post-agricultural succession in the karst region of southwest China.

Effects of long-term straw incorporation on lignin accumulation and its association with bacterial laccase-like genes in arable soils.

In this study, we aimed to investigate lignin accumulation and its relationship with the composition of bacterial laccase-like genes in three arable lands (i.e., upland limestone soil (UL), upland red soil (UR), and upland-paddy rotation red soil (UPR)), which are subjected to long-term straw incorporation. After 9-13years of straw incorporation, the lignin content significantly increased from 337.1, 414.5, and 201.6mg/kg soil to 2096.5, 2092.4, and 1972.2mg/kg soil in UL, UR, and UPR, respectively. The dominant lignin monomer changed from vanillyl (V)-type to cinnamyl (C)-type in UR. Both V- and C-types were the dominant monomers in UPR, and V-type monomer remained the dominant monomer in UL. Compared with the treatment without straw, straw incorporation significantly promoted the activity of laccase enzyme and the abundance of bacterial laccase-like genes in all soils. The redundancy analysis showed that the main influencing factors on lignin accumulation patterns with straw incorporation were the laccase enzyme activity, nitrogen availability, and some specific bacterial communities possessing the laccase-like genes (e.g., Thermotogae and Acidobacteria). The variation partitioning analysis confirmed that the strongest influencing factor on lignin accumulation was the composition of bacterial laccase-like genes (explained 31.4% of variance). The present study provides novel insights into the importance of bacterial laccase-like genes in shaping lignin monomer accumulation with straw incorporation in arable soils.

不同类型土壤栽培对苦丁茶树叶片生长和光合特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同类型土壤栽培对苦丁茶树叶片生长和光合特性的影响 DOI: 10.5846/stxb201806111303 作者: 作者单位: 福建农林大学林学院,贵州大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省科技攻关项目（黔科合NY字[2007]3040号） Effects of different soil types on growth and photosynthetic characteristics of Ligustrum robustum Author: Affiliation: College of Forestry,Fujian Agriculture and Forestry University,College of Forestry,Guizhou University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究苦丁茶树叶片生长与光合特性对不同类型土壤栽培的响应特征，确定最适苦丁茶栽培的土壤类型，可为高产优质化的苦丁茶种植业及其规模化生产基地的建立提供科学依据。通过土壤栽培实验研究了不同类型的土壤对苦丁茶树叶片生长、叶片解剖结构、叶绿素含量和光合特性的影响。结果表明：石灰岩土壤栽培条件下，苦丁茶叶长和叶面积比其他6种土壤栽培下的显著提高了34%-57%和43%-68%，叶绿素总量显著增加9%-33%，叶片、上下表皮、海绵组织和栅栏组织的厚度均显著高于其他6种土壤栽培。不同类型土壤栽培下苦丁茶净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和饱和蒸气压亏缺（Vpdl）的日变化趋势均呈单峰型，日均Pn和Tr值大小依次为：石灰岩 > 石英砂岩 > 玄武岩 > 长石石英砂岩 > 第四纪红色黏土 > 变余砂岩 > 煤系砂页岩，其中石灰岩土壤栽培下的日均Pn值相比其他6种土壤下的显著提高了13%-45%，且叶片最大净光合速率、表观量子效率、暗呼吸速率、光补偿点（LCP）和光饱和点（LSP）也最大，而煤系砂页岩栽培时最低，其LSP和LCP较石灰岩栽培的分别显著下降了40%和46%。综上，在7种类型的土壤中，石灰岩土壤栽培最有利于苦丁茶树叶片的生长发育、并促进叶绿素的合成和加强对光能的吸收利用，最终提高其叶片光合能力，其次为玄武岩土壤，而煤系砂页岩土壤是最不利于苦丁茶树叶片生长发育和光合作用。建议在苦丁茶种植业的发展和规模化生产基地建立时因选择由石灰岩性母岩发育的土壤进行栽培，从而提高苦丁茶的产量和品质。 Abstract:In this study, we investigated the effects of seven types of cultivation soil on leaf growth and photosynthetic characteristics of Ligustrum robustum (kuding tea) seedlings, aiming to provide scientific advices for cultivation and management of the species for cultivation and management of the species. We measured leaf length, width, area, spongy tissue thickness, palisade tissue thickness, layer of palisade tissue, chlorophyll content, and photosynthetic parameters of the seedlings grown in different soil types. The results showed that cultivation in limestone soil increased the length and area of the leaves by 34%-57% and 43%-68%, respectively, when compared with the other six soil types. In addition, leaf thickness, spongy tissue, and palisade tissue were significantly higher, and total chlorophyll content was 9%-33% higher in the limestone soil than in the other six soil types. The soil types did not affect the diurnal variation in net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and vapor pressure deficit (Vpdl). The daily average of Pn and Tr values in the seven soil types in descending order were as follows:limestone > quartz sandstone > basalt > feldspathic quartz sandstone > quaternary red clay > blastopsammite > coal sand shale. The daily average of Pn value was 13%-45% higher in limestone soil than in the other six soil types. Pn, Gs, and Tr were positively correlated, but they were negatively correlated with Vpdl. The maximum net photosynthetic rate, light saturation (LSP), light compensation (LCP), dark respiration rate, and apparent quantum yield were observed in limestone soil. LSP and LCP were significantly lower in coal sand shale soil (40% and 46%, respectively) than in the limestone soil. In summary, limestone soil is most beneficial for the growth and development of leaves. It can promote the production of chlorophyll and thus enhance the absorption and utilization of light energy and improve leaf growth and photosynthetic capacity. The second appropriate soil type is basalt. In contrast, coal sand shale soil is most unfavorable for the growth and development of leaves and photosynthesis. Therefore, limestone soil should be used for the large-scale plantation of L. robustum and improvement of the yield and quality of kuding tea. 参考文献 相似文献 引证文献

Effects of parent material on soil microbial biomass carbon and basal respiration within young afforested areas

ABSTRACTAfforestation is economically and ecologically important for protecting land and improving soil quality. This study evaluates how soil basal respiration, physicochemical and microbiological characteristics are affected by parent material variety in afforesting degraded areas. For this, some soil physical and chemical parameters, microbial respiration (MR), soil microbial biomass carbon and microbial indexes (Cmic/Corg and MR/Cmic) were determined. The results showed that the physical, chemical and microbiological properties of the soil formed from limestone were better than those of the basaltic-andesite soil. An independent samples t-test demonstrated that the afforested area on the limestone parent material had significantly higher microbial biomass C than the basaltic-andesite parent material. The microbial quotient (Cmic/Corg) of the limestone soil was positively affected by afforestation. In addition, the highest basal respiration value (1.01 ± 0.33 CO2–C 10−2 µg g−1 h−1) was observed for the limestone at the topsoil. The lowest metabolic quotient values were determined for the basaltic-andesite parent material on both topsoil and subsoil (1.99 and 1.42 μg CO2-C mg Cmic−1 h−1, respectively). This study revealed the importance of determining the parent material and its soil characteristics for successfully managing forest applications in degraded areas. Limestone soil sequesters more carbon and promotes microbial activities with a higher Cmic/Corg than the basaltic-andesite soil. Furthermore, the microbial quotient remained low during the 10 years in which the forest was in its sapling stage.

Diversity and functional characterization of antifungal-producing Streptomyces-like microbes isolated from the rhizosphere of cajuput plants (Melaleuca leucodendron L.)

The study was undertaken to evaluate the diversity of actinomycetes from the rhizosphere of the cajuput plant (Melaleuca leucodendron L.) using ARDRA, and to examine their in vitro antifungal potency against selected fungi. A total of 78 Streptomyces-like microbes were isolated from the limestone rhizosphere of cajuput plants and cultured in SN agar medium. The ability to inhibit fungal growth was observed using a dual culture assay. The diversity of the isolates was examined by morphological and genotype profiling using ARDRA (Amplified 16S ribosomal DNA restriction analysis), following which they were assigned to eight groups. Seventeen (21.8%) strains showed the ability to produce the antifungal compound as evidenced by their antagonism in vitro against the tested fungi, namely Saccharomyces cerevisiae BY 47420, Candida albicans CGMCC 2538, Aspergillus flavus NRLL 3357, and Fusarium oxysporum KFCC 11363P in the dual culture assay. One isolate, GMR22, which showed potent antagonism against unicellular and filamentous fungi, displayed 97% 16S rRNA sequence similarity to Streptomyces vayuensis. Keywords:Antifungal, Streptomyces-like microbes, Melaleuca leucadendron L., limestone soil, rhizosphere

Implication of different humic acid fractions in soils under karst rocky desertification

Karst rocky desertification, a kind of intense soil degradation, has become an urgent environmental issue in the karst region of southwest China. It was found that limestone soil, a typical soil of the karst region, is more vulnerable to karst rocky desertification than adjacent other soils although limestone soil has relatively high TOC (total organic carbon) content, but underlying mechanisms remain unclear. To investigate roles of soil properties in karst rocky desertification, three major soils, limestone soil, yellow soil and yellow brown soil, of the karst region of southwest China were sampled and their total extractable humic acid (THA) were fractionated into three sub-fractions, namely, free HA (HAf), encapsulated HA (HAe) and interacted HA (HAi), with a sequential extraction method. These soils and fractionated HA samples were systematically characterized with various analysis methods and discussed. The results showed that limestone soil had higher contents of total organic content (TOC) and THA content, but its THAC/TOC (carbon in THA to TOC) ratio (23.39%) was lower than those of yellow soil (31.44%) and yellow-brown soil (30.74%); C/N ratios and total acid contents of HAe and HAi fractions, which were physically protected by soil minerals/aggregates, were much higher than those of HAf fractions, indicating that HAe and HAi could be more active and degraded easier than HAf once exposed to microbes or/and runoff erosions. Therefore, lower HAf content and significantly lower HAfC/TOC (carbon in HAf to TOC) ratio of limestone soil may underlie the observation that limestone soil showed weak resistance to karst rocky desertification compared to other adjacent soils when the site had been artificial disturbed. We believe that roles of different HA fractions to overall quality and stability of soil deserve more attention.

Interpretation of regional-scale distribution of high Hg in soils of karst area in southwest China

The abundance and spatial distribution of mercury in soil samples covering nearly the whole of China ( c . 9 million km 2 ) were obtained by the China Geochemical Baseline (CGB) project from 2008 to 2015. From the data and maps, it was found that the Hg contents both in the top (0–25 cm) and deep soil (below 100 cm or C-horizon) of the karst area in southwestern China are richer than that of any other geographical landscape areas. Median Hg values for this karst area are 113 and 90 µg/kg respectively ( n = 126), in the top and bottom soils, much higher than the corresponding data of 26 and 18 µg/kg for the entire country ( n = 3380). This regional-scale high Hg distribution is due mainly to high Hg geochemical backgrounds in bedrock and soil formation on limestone. A large-scale epithermal metallogenic domain developed in southwestern China and the extensive distribution of Lower Cambrian black shale in southwest China led to a high Hg geochemical background for parent rocks of soils. The chemical weathering of carbonate minerals and the geochemical behaviour of Hg in the epigenetic environment result in Hg enrichment by ferric oxides, iron hydroxide and organic carbon in limestone soils. Human activities mostly result in local-scale Hg anomalies, but have little effect on this regional-scale anomaly.

Significant release and microbial utilization of amino sugars and d-amino acid enantiomers from microbial cell wall decomposition in soils

Amino sugars and d-amino acid enantiomers are major components of bacterial and fungal cell walls (i.e. peptidoglycan and chitin) and are often used as biomarkers of microbial residue turnover in soils. However, little is known about the in situ decomposition rates of microbial cell wall residues and how soil physicochemical properties affect this process. In this study, we investigated the in situ gross production and consumption rates of free amino sugars (glucosamine and muramic acid) and amino acids (meso-diaminopimelic acid, l-alanine, and d-alanine) by a novel isotope pool dilution assay using 15N-labeled amino compounds. Soils were obtained from six sites differing in land management (cropland, pasture, and forest) and bedrock (silicate and limestone) and incubated at three temperatures (5, 15, and 25 °C). Free glucosamine released during the decomposition of peptidoglycan and chitin contributed significantly to the extractable soil organic nitrogen pool. Gross production and consumption rates of glucosamine were higher than those of individual amino acids, i.e. L- and d-alanine. Muramic acid had a longer mean residence time (68 h compared to 2.7 h for glucosamine, L- and d-alanine) and made a negligible contribution to soil organic nitrogen fluxes, indicating that free muramic acid was not a major decomposition product of peptidoglycan in soils. Meso-diaminopimelic acid and d-alanine exhibited comparable gross production and consumption rates with l-alanine. These amino acids can be used as indicators to estimate the decomposition of peptidoglycan from bacterial cell wall residues. We found that chitin decomposition was greater in silicate soils, while peptidoglycan decomposition dominated in limestone soils. Glucosamine production rates were not correlated with soil total amino sugars, microbial community structure, or hydrolytic enzyme activities, but were highest in soils with low pH and high sand content, indicating that soil texture and soil pH may strongly influence the decomposition of amino sugar polymers. In contrast, mDAP, L- and d-alanine gross production and consumption rates were positively correlated with soil pH and clay content, due to greater depolymerization of peptidoglycan stem peptides in limestone soils. This isotope pool dilution approach strongly improves our understanding of the mechanisms and environmental controls on microbial cell wall decomposition in soils.

Concentration of some metals in soil and plant organs and their biochemical profiles in Tulipa luanica, T. kosovarica and T. albanica native plant species

The purpose of this study was to determine the concentration of some metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, Ca and Mg) in soil of serpentine and limestone sites, their bioaccumulation and impact on some biochemical parameters in T. luanica, T. kosovarica and T. albanica plants. T. kosovarica and T. albanica grows in serpentine soil, while T. luanica grow in limestone soil. The research showed that concentrations of Cd, Co, Cr, Fe, Mn and Ni were significantly higher at serpentine soil sites in comparison with limestone sites, while concentrations of Pb, Cd, Co and Cr in bulbs, leaves and seeds were under the limit of detection. The concentration of Ni in plant samples of T. kosovarica was significantly higher in comparison with its concentration in T. albanica, but itwas under the limit of detectionin T. luanica. Moreover, concentrations of Al and Fe in leaves of T. kosovarica and T. albanica were higher in comparison with T. luanica. The concentration of Mg was significantly higher in T. kosovarica and T. albanica than in T. luanica. The δ-aminolevulinic acid dehydratase activity, malondialdehyde and glutathione contents in leaves of T. luanica were higher in comparison with T. kosovarica and T. albanica. In addition, the amounts of total chlorophyll and δ-aminolevulinic acid (ALA) in leaves of T. albanica were higher in comparison with T. kosovarica and T. luanica. Our findings show that target organs of metal accumulation in three Tulip species appears to be leaves > seeds > bulbs, while the biochemical parameters show that limestone sites represent a less stressful habitat for growing these plant species in comparison with serpentine sites.

Microbiome and ecotypic adaption of Holcus lanatus (L.) to extremes of its soil pH range, investigated through transcriptome sequencing

BackgroundPlants can adapt to edaphic stress, such as nutrient deficiency, toxicity and biotic challenges, by controlled transcriptomic responses, including microbiome interactions. Traditionally studied in model plant species with controlled microbiota inoculation treatments, molecular plant-microbiome interactions can be functionally investigated via RNA-Seq. Complex, natural plant-microbiome studies are limited, typically focusing on microbial rRNA and omitting functional microbiome investigations, presenting a fundamental knowledge gap. Here, root and shoot meta-transcriptome analyses, in tandem with shoot elemental content and root staining, were employed to investigate transcriptome responses in the wild grass Holcus lanatus and its associated natural multi-species eukaryotic microbiome. A full factorial reciprocal soil transplant experiment was employed, using plant ecotypes from two widely contrasting natural habitats, acid bog and limestone quarry soil, to investigate naturally occurring, and ecologically meaningful, edaphically driven molecular plant-microbiome interactions.ResultsArbuscular mycorrhizal (AM) and non-AM fungal colonization was detected in roots in both soils. Staining showed greater levels of non-AM fungi, and transcriptomics indicated a predominance of Ascomycota-annotated genes. Roots in acid bog soil were dominated by Phialocephala-annotated transcripts, a putative growth-promoting endophyte, potentially involved in N nutrition and ion homeostasis. Limestone roots in acid bog soil had greater expression of other Ascomycete genera and Oomycetes and lower expression of Phialocephala-annotated transcripts compared to acid ecotype roots, which corresponded with reduced induction of pathogen defense processes, particularly lignin biosynthesis in limestone ecotypes. Ascomycota dominated in shoots and limestone soil roots, but Phialocephala-annotated transcripts were insignificant, and no single Ascomycete genus dominated. Fusarium-annotated transcripts were the most common genus in shoots, with Colletotrichum and Rhizophagus (AM fungi) most numerous in limestone soil roots. The latter coincided with upregulation of plant genes involved in AM symbiosis initiation and AM-based P acquisition in an environment where P availability is low.ConclusionsMeta-transcriptome analyses provided novel insights into H. lanatus transcriptome responses, associated eukaryotic microbiota functions and taxonomic community composition. Significant edaphic and plant ecotype effects were identified, demonstrating that meta-transcriptome-based functional analysis is a powerful tool for the study of natural plant-microbiome interactions.

Cadmium bioavailability well assessed by DGT and factors influencing cadmium accumulation in rice grains from paddy soils of three parent materials

High Cd resulted from natural background or agricultural activities in some of the paddy soils in South China is a concern. It is imperative to understand the relationship between Cd bioavailability in high Cd soils and Cd accumulation in rice grains. Therefore, our objectives are to explore the relationship between Cd accumulation in rice grains and Cd availability which was characterized with five different methods, and to investigate factors influencing Cd accumulation in rice. One hundred and twenty-two paired soil and rice plant samples were collected from paddy fields of three parent materials (sandshale, limestone, and Quaternary red earth) in Guangxi Province. Soil Cd availability was assessed using three chemical extractants (0.43 M HNO3, 0.01 M CaCl2, and 0.005 M DTPA) and compared with Cd in soil solution and that sampled by the diffusive gradients in thin films (DGT) method. A five-step sequential fractionation of Cd was also carried out. Random forest (RF) was employed for assessing factor relative importance in Cd accumulation in rice plants and grains in high Cd soils. All of the soil samples had a total Cd content exceeding the maximum permissible concentration (0.3 mg kg−1) for soils with the exchangeable fraction taking up 50, 56, and 39%, respectively. For the rice grains harvested from the soils derived from sandshale, limestone, and Quaternary red earth, 67, 95, and 28%, respectively, had a Cd content exceeding the maximum permissible concentration for grain (0.2 mg kg−1). The results demonstrated high Cd bioavailability in these areas and indicated potential health risk when people ingest the rice grains. Cd measured by DGT best reflected Cd bioavailability. The Cd in soil solution (Cdsoln), which is directly available, and CaCl2-extracted Cd were also significantly related to grain Cd content. Factor relative importance assessment based on random forest (RF) showed that soil pH was among the top two most important physicochemical factors of the three types of soils influencing Cd accumulation in rice grains. Besides, dissolved organic carbon (DOC), clay, and dithionite-citrate-bicarbonate-extracted Mn (MnDCB) was the other major influencing factor in the sandshale soils, limestone soils, and Quaternary red earths, respectively. The results indicated that DGT technique better predicted Cd bioavailability. Manipulating soil pH could be used to reduce Cd bioavailability and its accumulation in plants. However, manipulating soil DOC, clay and Fe/Mn content were soil-type-dependent.

Does soil moisture availability explain liana seedling distribution across a tropical rainfall gradient?

AbstractLiana density tends to increase with decreasing rainfall and increasing seasonality. However, the pattern of liana distribution may be due to differences in soil water retention capacity, not rainfall and seasonality per se. We tested the effect of rainfall and soil substrate with respect to the distribution of liana seedlings in six sites across a rainfall gradient from the wet Atlantic to the dry Pacific in central Panama. Soils were either limestone, with low water‐holding capacity, or laterite, with higher water‐holding capacity. We sampled liana seedlings at each site using three 1 × 100 m transect. We found that relative liana seedling density was higher on limestone soils compared to laterite soils regardless of the amount of rainfall. Furthermore, liana community composition on limestone soils was more similar to dry forest sites than to adjacent wet and moist forest sites. Liana seedling species diversity relative to trees was significantly higher in a low‐fertility dry forest site compared to a high‐fertility forest, but did not differ from the other sites. Thus, liana seedling density and community structure may be driven more by soil type and thus by soil moisture availability than strictly by mean annual rainfall and the seasonality of rainfall.

Relationship between resistivity and soil strength based on geoelectric data

Geoelectric method was applied in geophysical research to know the relationship between resistivity with soil strength based on geoelectric data has been conducted at Cassa Villa Jimbaran, Badung, Bali. The study lies in the position of 8°46'50,6 LS and 115°10'02,6 BT. The data was collected by injecting an electric current inside the Earth's surface using a Wenner configuration with a path length of 148.8 meters. The data was processed using SiberTool Software to export *.d2d to *.dat file. Therefore, it can be read by Res2dinv software. The further data was processed using Res2dinv for data inversion. Thus, it was able to show the contour of the cross-section of the trajectory. The research result was obtained resistivity value at position 51.15 was 6, 40 - 11, 98 ?m. The data of the soil strength was applied Standard Penetration Test (SPT) method by drilling and taking soil samples then testing in the laboratory. The soil sample was taken at position 51.15. The soil strength test result was obtained about 6 - 5, 3 (kg/cm) ^2 at a depth of 0, 58 - 20, 0 meters. The two magnitudes were analyzed to find the relationship in the form of the two poly nomialorde y=-60,811 x^2+1433,4 x-8442,4 with correlation coefficient value 0, 9799. It means there was a correlation between resistivity values with soil strength. It is as well as to define the soil strength value can be reviewed based on resistivity especially limestone soil.

X-射线荧光光谱压片法测定土壤中元素含量

利用X-射线荧光光谱压片法对土壤中元素的含量进行测定，并对测定的结果进行分析研究。结果表明，土壤中金属与非金属含量都较高，部分土壤元素含量比较接近于石灰岩土壤。 The content of elements in soil was determined by X ray fluorescence spectrometry (XRF), and the results were analyzed and studied. The results show that the content of some metal and non-metal elements in soil is high, and the content of elements in soil is close to that of limestone soil.

桂西北喀斯特地区石灰土养分空间变异特征

PDF HTML阅读 XML下载 导出引用 引用提醒 桂西北喀斯特地区石灰土养分空间变异特征 DOI: 10.5846/stxb201706081043 作者: 作者单位: 广西农业科学院农业资源与环境研究所,广西农业科学院农业资源与环境研究所,中国科学院亚热带农业生态研究所,广西桂江林业调查规划设计有限公司,广西农科院农业资源与环境研究所,广西农科院农业资源与环境研究所,广西农科院农业资源与环境研究所,广西农科院农业资源与环境研究所,广西农科院农业资源与环境研究所,中国科学院亚热带农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31460135）；广西第十八批"十百千人才工程"专项；广西农业科学院科技发展基金项目（桂农科2017JM08，2015JZ17）；广西农业科学院基本科研业务专项（2015YT31，桂农科2016YM56） Spatial variability of limestone soil nutrients in a Karst area of Northwestern Guangxi Author: Affiliation: Agricultural Resources and Environment Research Institute, Guangxi Academy of Agricultural Sciences,Agricultural Resources and Environment Research Institute, Guangxi Academy of Agricultural Sciences,,,,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:从区域尺度出发，将整个桂西北喀斯特地区作为研究区域，以大面积野外调查采样和室内分析数据为基础，采用经典统计学和地统计学方法，探索喀斯特区域内石灰土养分的空间异质性和分布格局。结果表明：桂西北喀斯特地区石灰土pH为弱变异，其他养分变异系数为30%-75%，变异程度中等。石灰土各养分的空间变异特征不同，土壤有机质（SOM）、速效磷（AP）和速效钾（AK）的最佳拟合模型依次为球状模型、高斯模型和线性模型，pH、碱解氮（AN）、全氮（TN）、全磷（TP）和全钾（TK）的最佳拟合模型均为指数模型。SOM、AP、TN和TP表现为中等空间相关性，空间差异是由随机因素和结构性因素共同作用引起的；pH、AN、AK和TK呈弱空间相关性，空间变异主要受随机因素的控制；SOM和TN的空间变异尺度较大，pH、AN和TK的空间变异尺度最小。SOM、TN、TP和AP养分含量呈自西向东逐渐减少的趋势，pH、AN、AK和TK在区域尺度上的分布没有呈现一定的规律性。相关分析结果表明，在区域大尺度下，地形因子（如海拔、坡度和岩石裸露率等）和植被类型是影响桂西北喀斯特石灰土空间变异特征的重要因素。 Abstract:Large-scale spatial heterogeneity and distribution patterns of limestone soil nutrients in the karst areas of northwestern Guangxi were evaluated in this study, based on regional field survey and laboratory analysis combing with classical statistics and geostatistics. The results showed that pH value of limestone soil had little variation in the karst areas of Northwestern Guangxi, while the variation coefficients of soil nutrients ranged from 30% to 75%, which can be considered as moderate variation. The characteristics of spatial variability differed among soil nutrients. Spherical model, Gaussian model, and linear model were the best-fit model for soil organic matter (SOM), available phosphorus (AP), and available potassium (AK), respectively. However, pH, available nitrogen (AN), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) could be best fitted by exponential model. In addition, SOM, AP, TN, and TP showed moderate spatial autocorrelation, and spatial variability was caused by both random and structural factors. On the other hand, pH, AN, AK, and TK showed weak spatial autocorrelation, and spatial variability was mainly controlled by random factors. The variation range for SOM and TN were large while that for pH, AN, and TK were small. The contents of SOM, TN, TP, and AP exhibited a decreasing trend from west to east but the distribution of pH, AN, AK, and TK did not show any regularity on a regional scale. The correlation analysis demonstrated that, on a large scale, topographic factors (i.e., altitude, slope and rock exposure rate) and vegetation type were important factors affecting the spatial variability of limestone soil nutrients in the karst areas of northwestern Guangxi. 参考文献 相似文献 引证文献