基于Ypt1基因为靶标的木香疫病病组织及病田土壤分子检测技术(英文)

A species-specific PCR assay was established for rapid and accurate detection of the oomycete pathogen Phytophthora tentaculata in diseased plant tissues and infected soil.A pair of species-specific primers Pt1/Pt2 were designed on the basis of Ras-related protein(Ypt1) gene sequences of the Phytophthora species.PCR amplification with the Pt primers resulted in a 386 bp product only from isolates of P.tentaculata.The detection threshold with Pt primers was 100 pg of genomic DNA.A nested PCR procedure was developed using Ypt1F/Ypt1R as the first-round amplification primers and Pt1/Pt2 as the second-round primers,which increased the detection sensitivity 100-fold to 1 pg.PCR using these Pt primers can also be used to detect P.tentaculata in naturally infected plant tissues and soil.The PCR-based method developed in this study provides a rapid and sensitive tool for detection of P.tentaculata.

高分子土壤改良剂对种籽萌芽之影响研究(英文)

以高分子材料为土壤改良剂可使土壤团粒化,增加水份入渗效率,减少土壤冲蚀,为研究环境问题之重要课题。但此类土壤改良剂可能抑制植物种籽萌芽,为使用此种材料的一大问题。以压克力与聚乙烯醇对Bahia种籽做一系列萌芽实验探讨。实验结果发现,压克力对种籽萌芽率与萌芽势能有严重之抑制作用。但适量之聚乙烯醇添加可克服此问题。

生物质炭施用对水稻土有机质分子结构和组成的影响

农田土壤施用生物质炭(BC)被认为是提高表层土壤固碳潜力的有效措施,但其对深层土壤有机质分子结构和组成特征的影响还认识不足.本文以BC施用4年后的水稻土为研究对象,基于傅里叶变换红外光谱(FTIR)和热裂解气质联用(Py-GC/MS)技术,探究BC施用对耕作层(A层,0~15 cm)、犁底层(Ap层,15~28 cm)和潴育层(W,28~50 cm)土壤有机碳(SOC)含量和有机质分子结构与组成的影响.结果表明:①与不施炭的对照(CK)处理相比,BC处理下A层SOC和可溶性有机碳(DOC)含量分别显著增加了13.0%和22.3%,Ap层DOC含量增加了20.8%,而W层SOC和DOC含量均无显著性变化.②从有机质化学结构来看,BC施用增加了各土层芳香族碳组分的相对峰强度,而降低了A层和Ap层多糖等碳水化合物的相对峰强度,有机质结构趋于芳香化.③BC施用明显增加了不同深度水稻土有机质分子的相对丰度并改变了分子组成.与CK处理相比,BC处理降低了各土层中氨基酸、氨基化合物、二元羧酸、羟基酸和糖类的相对丰度,特别是Ap层和W层;而BC处理则增加了各土层中烷烃类、胺类、杂环氮化合物、苯酚酯和多酚类的相对丰度.研究显示,施用BC增加了表层土壤中疏水性分子和芳香性化合物向深层土壤的迁移,增强了深层土壤碳库的稳定性.

不同土地利用方式下土壤有机质分子组成变化的整合分析

利用生物标志物研究土壤有机质(SOM)分子组成可用于分析有机质的来源及降解,从分子层面揭示土壤有机碳(SOC)的稳定机制.为了进一步明确不同土地利用方式对土壤有机质分子组成的影响,通过对已发表的研究数据进行整合分析,研究了全球尺度上农田、草地和森林这3种土地利用方式下有机质分子组成(游离脂质、角质、木栓质和木质素)的变化.结果表明,不同土地利用方式下有机质分子组成有明显差异,森林土壤游离态脂类(烷烃、烷酸、烷醇和环脂)、角质和木质素酚含量显著高于草地和农田,草地和森林土壤的木栓质含量无显著差异,草地木栓质与角质的比值最高,平均为2.96,农田和森林平均分别为1.68和2.21.农田土壤的丁香基的酸醛比(Ad/Al)S和香草基的酸醛比(Ad/Al)V最大,分别为1.25和1.58,显著高于草地(0.46和0.69)和森林(0.78和0.7).且相关性分析结果表明,农田土壤中,木栓质与年均降雨量(MAP)和黏粒呈显著相关,角质与黏粒呈显著相关,木质素与年均温度(MAT)、MAP、砂粒和容重呈显著相关;草地土壤中,总游离脂质与MAP和容重呈显著相关,木栓质和角质均与MAT和MAP呈显著相关,木质素与MAP、pH、砂粒和容重呈显著相关;森林土壤中,仅木质素与MAP和砂粒呈显著相关.总体而言,3种土地利用方式下,森林土壤中有机碳和各分子组分含量均较高,草地土壤中植物根系对于土壤有机质的贡献更大,农田土壤中,由于人为耕作活动而加速了木质素的降解.未来研究应进一步关注土壤理化性质和气候条件对于有机质分子组成的调控.

四川大头茶地理分布与环境因子的关系

The geographic distribution of Gordonia acuminata in four provinces of Yunnan,Guizhou,Sichuan and Guangxi is disconnected. The whole distribution region is divided into three parts: Sichuan(A), Guangxi(B), Yunnan(C). The Kira’ WI and CI indices and the Xu wenduo’ index were used to analyze the water and thermal range of the species distribution. The adaptive range of G. acuminata to light, soil type and pH was also discussed.

Phenotypic Plasticity in Response to the Heterogeneous Water Supplyin the Rhizomatous Grass Species, Calamagrostis epigejosin the Mu Us Sandy Land of China

Calamagrostis epigejos (L.) Roth. is a perennial grass with slender and long rhizome segments between interconnected neighbor ramets. To investigate the phenotypic plasticity in response to the heterogeneous soil water supply, ramet pairs of the species were subjected to heterogeneous water supply by which either mother ramets or daughter ramets were in high or low soil water supply, respectively, in the Maowusu (Mu Us) Sandy Land of Nei Mongol. The results showed that the phenotypic characteristics of the individual ramets of C epigejos were greatly influenced by the heterogeneous water supply. The ramets treated with high water supply significantly produced more new rhizomes and more offspring (ramets), and accumulated more shoot biomass, and allocated more biomass to their shoots than those treated with low water supply. In comparison with the daughter ramets in homogeneous soil water supply, phenotypic characteristics, in terms of new rhizome growth, the production of new offspring, and the biomass allocation pattern, of the daughter ramets within the pairs of the species were not significantly changed, no matter that high or low soil water supply to mother ramets. The phenotypic responses of mother ramets to soil water supply were similar to those of daughter ramets. From these results, it is inferred that the interconnected ramets of C epigejos response phenotypically to their local soil water rather than to the soil water experienced by the interconnected ramets. The interconnected ramets of C epigejos might be independent of each other in water relationship, although they are physically interconnected with rhizome segments. The physiological independence of interconnected ramets might facilitate the risk spreading and thus enhance the genet survivorship under the frequent drought stresses in Mu Us Sandland.

Effect of Water Supply on Seed Germination of Soil Seed-bank in Desert Vegetation

在温室条件下 ,进行了水涝和保湿 2种水分供应试验。结果表明 ,在土壤种子库中 ,有 3种植物的种子在水涝条件下的萌发数量明显较大 ;9种植物在保湿条件下的萌发数量明显较大 ;18种植物在 2种水分供应条件下的萌发数量没有明显差异。当植物的土壤种子密度较低时在不太合适的萌发条件下表现为不存在。研究结果强调在进行土壤种子库分析之前预备萌发试验的必要性。同时也揭示出利用一种标准的水分供应处理方法去分析来自不同生境土样里种子库的危险性。

Effects of Different Illumination Intensity and Soil Moisture on Seed Germination of Parashorea chinensis

Objective] This study almed to soIve technical probIems in artificial breed-ing of Parashorea chinensis. [Method] The effects of different iI umination intensity and soiI moisture on seed germination rate and emergence of P. chinensis were in-vestigated. [Result] Under conditions of ill umination intensity of 40% and soiI mois-ture of 60%, the seeds of P. chinensis showed the highest germination rate. [Con-clusion] This study wiI provide some basic information for the ex-situ conservation, repopuIation and deveIopment and utiIization of P. chinensis.

Identification and Cu Enrichment Capacity of TLSB_2-K, a Cu-tolerant Strain

[Objective] The Cu-tolerance and Cu enrichment capacity of TLSB2-K were investigated. [Method] The previously isolated TLSB2-K strain was identified though morphological observation, gram staining and 16S rDNA sequence alignment. In ad- dition, the effects of temperature, pH and osmotic pressure on the growth of strain were also investigated by using shaking culture. The Cu-tolerance and Cu enrich- ment capacity of TLSB2-K strain under Cu stress were also studied. [Result] The results showed TLSB2-K belongs to Bacillus spp., and its optimum growth conditions were as follows： temperature, 27 ~C; pH, 7.0; osmotic pressure, 1.1% NaCI. When the Cu concentration ranged from 100 mg/L to 500 mg/L, the strain grew well; when the Cu concentration ranged from 100 mg/L to 400 mg/L, the Cu content in bacteria was increased with the increase of Cu concentration; when the Cu con- centration was 400 mg/L and the incubation time was 30 h, the Cu content in bac- teria reached the peak （2 250 mg/kg）; the highest tolerant concentration was 700 mg/L. [Conclusion] TLSB2-K strain had relatively high Cu tolerance and Cu enrich- ment capacity. They had important theoretical research and engineering application values.

Dissolution of Aluminum in Variably Charged Soils as Affected by Low-Molecular-Weight Organic Acids

Low-molecular-weight （LMW） organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and A1 detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of A1 in the two investigated soils in the following order： citric 〉 oxalic 〉 malonic 〉 malic 〉 tartaric 〉 salicylic 〉 lactic 〉 maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of A1 increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-I, the dissolution of A1 changed Iittle with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L^-1,the dissolution of A1 increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of A1 were also related to their sorption-desorption equilibrium in the soils.

Species concepts and biodiversity in Trichoderma and Hypocrea:from aggregate species to species clusters?

Trichoderma/Hypocrea is a genus of soil-borne or wood-decaying fungi containing members important to mankind as producers of industrial enzymes and biocontrol agents against plant pathogens, but also as opportunistic pathogens of immunocompromised humans. Species identification, while essential in view of the controversial properties of taxa ofthis genus, has been problematic by traditional methods. Here we will present a critical survey of the various identification methods in use. In addition,we will present an update on the taxonomy and phylogeny of the 88 taxa (which occur as 14 holomorphs, 49 teleomorphs and 25 anamorphs in nature) of Trichoderma/Hypocrea that have been confirmed by a combination of morphological, physiological and genetic approaches.

Fractionation of Heavy Metals in Soils as Affected by Soil Types and Metal Load Quantity

Two series of soil subsamples, by spiking copper (Cu), lead (Pb), zinc (Zn) and cadmium (Cd) in an orthogonal design, were prepared using red soil and brown soil, respectively. The results indicated that heavy metal fractions in these soil subsamples depended not only on soil types, but also on metal loading quantity as well as on interactions among metals in soil. Lead and Cu in red soil appeared mostly in weakly specifically adsorbed (WSA), Fe and Mn oxides bound (OX), and residual (RES) fractions. Zinc existed in all fractions except organic bound one, and Cd was major in water soluble plus exchangeable (SE) one. Different from the results of red soil, Pb and Cu was present in brown soil in all fractions except organic one, but over 75% of Zn and 90% of Cd existed only in SE fraction. Meanwhile, SE fraction for any metal in red soil was lower than that in brown soil and WSA and OX fractions were higher. It is in agreement with low cation exchange capacity and large amounts of metal oxides included in red soil. Metal fractions in soil, especially for water soluble plus exchangeable one, were obviously influenced by other coexisting metals. The SE fraction of heavy metals increased with increasing loading amounts of metals in red soil but not obviously in brown soil, which suggest that metal availability be easily affected by their total amounts spiked in red soil. In addition, more metals in red soil were extracted with 0.20 mol L-1 NH4Cl (pH 5.40) than that with 1.0 mol L-1 Mg(NO3)2 (pH 7.0), but the reverse happened in brown soil, implicating significantly different mechanisms of metal desorption from red soil and brown soil.

Distribution of Exchangeable Calcium，Magnesium and Potassium as Affected by Fertilizer Application to Red Soil

A leaching experiment was carried out with repacked soil columns in laboratory to stndy the leachingprocess of a red soil derived from sandstone as affected by warions fertilization practices. The treatments wereCK (as a control), CaCO_3, CaSO_4, MgCO_3, Ca(H_2PO_4)_2, Urea, KCl, Mnltiple (a mixture of the above-mentioned fertilizers), and KNO_3. The fertilizers were added to the bare surface of the soil columns, andthen the columns were leached with 120 mL deionized water daily through peristaltic pumps over a periodof 92 days. At the end of leaching process, soils were sampled from different depths of the soil profiles, i.e.,0-5 cm, 5-10 cm, 10-20 cm, 20-40 cm, and 40-60 cm. The results showed when applying Ca, Mg, andK to the bare surface of the soil columns, exchangeable Ca￣(2+), Mg￣(2+), and K￣+ in the upper layer of thesoil profile increased correspondingly, with an extent depending mainly on the application rates of Ca, Mg,and K and showing a downward trend. CaCO_3, CaSO_4, MgCO_3, and Ca(H_2PO_4)_2 treatments had scarcelyany effect on movement of exchangeable K￣+, while CaCO_3, and CaSO_4 treatments significantly promotedthe downward movement of exchangeable Mg￣(2+) although these two treatments had no obvious effect onleaching losses of Mg. The fact that under Urea treatment, exchangeable Ca￣(2+) and Mg￣(2+) were higheras compared to CK treatment showed urea could prevent leaching of exchangeable Ca￣(2+) and Mg￣(2+). Theobvious downward movement of exchangeable Ca￣(2+) and Mg￣(2+) was noticed in KCl treatment. In Multipletreatment, the downward movement of exchangeable Ca￣(2+) and Mg￣(2+) was evident, while that of K￣+ was lessevident. Application of KNO_3 strongly promoted the downward movement of exchangeable Ca￣(2+) and Mg￣(2+)in the soil profile.

Experimental study on the moving characteristics of fine grains in wide grading unconsolidated soil under heavy rainfall

The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.

Isolation and Characterization of Phosphate-Solubilizing Bacteria from Seagrass Rhizosphere Soil

Phosphate-solubilizing bacterial strains(6 Nos.) were isolated from the rhizosphere soils of two seagrasses(Halophila ovalis(R.Br.) Hook and Halodule pinifolia(Miki) Hartog) in the Vellar estuary.Experimental studies found that the strain PSSG6 was effective in phosphate solubilization with Phosphate Solubilization efficiency index E = 375 ± 8.54,followed by the strain PSSG5 with Phosphate Solubilization efficiency index E = 275 ± 27.3.Of the 6 strains isolated,the strains PSSG4 and PSSG5 be-longed to the genus Bacillus,and PSSG1,PSSG2 and PSSG3 were identified as Citrobacter sp.,Shigella sp.,and Klebsiella sp.,respectively,by conventional method,and PSSG6 was identified as Bacillus circulans using conventional and molecular methods.

Changes of Soil Water, Organic Matter, and Exchangeable Cations Along a Forest Successional Gradient in Southern China

Information on the distribution patterns of soil water content （SWC）, soil organic matter （SOM）, and soil exchangeable cations （SEC） is important for managing forest ecosystems in a sustainable manner. This study investigated how SWC, SOM, and SEC were influenced in forests along a successional gradient, including a regional climax （monsoon evergreen broad-leaved forest, or MEBF）, a transitional forest （coniferous and broad-leaved mixed forest, or MF）, and a pioneer forest （coniferous Masson pine （Pinus rnassoniana） forest, or MPF） of the Dinghushan Biosphere Reserve in the subtropical region of southern China. SWC, SOM, and SEC excluding Ca^2＋ were found to increase in the soil during forest succession, being highest in the top soil layer （0 to 15 cm depth） except for Na^＋. The differences between soil layers were largest in MF. This finding also suggested that the nutrients were enriched in the topsoil when they became increasingly scarce in the soil. There were no significant differences （P = 0.05） among SWC, SOM, and SEC. A linear, positive correlation was found between SWC and SOM. The correlation between SOM and cation exchange capacity （CEC） was statistically significant, which agreed with the theory that the most important factor determining SEC is SOM. The ratio of K^＋ to Na^＋ in the topsoil was about a half of that in the plants of each forest. MF had the lowest exchangeable Ca^2＋ concentration among the three forests and Ca^2＋：K^＋ in MPF was two times higher than that in MF. Understanding the changes of SWC, SOM, and CEC during forest succession would be of great help in protecting all three forests in southern China.

Call for Papers-Molecular Soil Biology(ISSN 1925-2005)

Molecular Soil Biology (ISSN 1925-2005), an open access, peer reviewed journal, publishing original contribution related to the soil biology at the molecular level. All manuscripts

Comparative analysis of some selected macronutrients of soil in orange orchard and degraded forests in Chittagong Hill Tracts,Bangladesh

Status of organic carbon (C), total nitrogen (N), available potassium (K), calcium (Ca) and phosphorus (P) in three different depths (0-5 cm, 5-15 cm and 15?30 cm) on two hill slopes of 35% and 55% in orange orchard cultivated by the Mro tribe of Chittagong Hill Tracts (CHTs) were evaluated and compared with those in degraded bush forests, through digging three profiles in each land use. The content of all the five nutrients was found to be higher in the soil of orange orchard than in the soil of forest. But the variation was not consistent for both the slopes. The content varied depth wise also, having the highest value in surface soil in case of both the land uses on both the slopes. A mean available K content was significantly higher in orange orchard than in forest on 55% slope, while it was lower on 35% slope. Surface soil contained the nutrients of K and Ca with the amount of 0.2905-mg·g^(-1) soil and 3.025-mg·g^(-1)soil respectively in the orchard, while 0.1934-mg·g^(-1) soil and 1.6083-mg·g^(-1) soil were respectively in the forest. Organic carbon and total nitrogen were found more or less similar in surface soil on both the land uses showing a slight difference. Available P was found only in orange orchard, and in forest it was too little in amount to detect by the spectrophotometer. The degraded forests were poor in nutrient content due to high rate of soil erosion, which would be possible to be improved by bringing it under tree cover as proved by the adaptation of orange orchard there.

Salt－Water Dynamics in Soils：IV．Changes of Ionic Composition in Soil Profiles During Water Evaporation and Infiltration

Through a simulation test carried out with soil columns (61.8 cm in diameter), the changes of ioniccomposition in soil profile during the processes of water evaporation and infiltration were studied. Underevaporation conditions, ions moving upward with fresh groundwater were mainly Cl￣-, SO, Ca￣(2+), andNa￣+. When the mineralized groundwater took part in the salt accumulation, the ionic composition in soilswas close to that in ground water supplemented. Under rainfall infiltration conditions, the salt-leaching roleoccurred mainly in the top soil. With the decrease of total salt content, NO and Cl￣- reduced rapidly, SOdecreased slowly, but HCO had a little change only. Among cations, Na￣+ and Ca￣(2+) contents lowered atthe same speed, and Mg￣(2+) decreased slowly.

Experimental study on dispersive soil in western Jilin

In order to research engineering geological properties of the soil in Zhenlai of western Jilin, especially the dispersivity of soil, the authors carried out the basic physicocbemical test and dispersivity identification test. The results show that the dispersivity of the soil increases with the increase of depth within 0-30 cm （surface soil） ; it decreases as the depth increases within in 30-100 cm. Furthermore, the statistical analysis of the dispersivity indexes and physicochemical propertity indexes show that the DP is positively linear correlated with total soluble salt content, sodium ion content, ESP, pH and organic matter content. Meanwhile, it is negatively linear correlated with clay content, and the linear relationship is better. Through the study of the dispersion mechanism of soil samples, it can be concluded that sodium montmorillonite, higher percentage of exchangeable sodium and high pH are the main reasons for the dispersion of soils in western Jilin.