黄河口湿地土壤中生物硅的分布与植硅体的形态特征

硅是地壳中重要元素之一,深刻影响着地表物质循环。湿地是全球碳、硅循环和气候变化研究的重要组成部分,然而针对湿地硅循环方面的研究较少。本文分别运用化学提取法和无损提取法,得出了黄河口三角洲湿地地表土壤中生物硅的含量、组成,并对湿地硅的分布特征与影响因素进行了研究。结果发现:黄河口湿地生物硅含量介于2.48~19.3 g/kg之间,并具有冬季高、秋季低的特点;生物硅与颗粒有机碳和颗粒有机氮含量具有显著的正相关关系,表明三者具有相似的来源;生物硅和植物可利用硅之间显著的相关性表明生物硅在土壤硅循环中起着主要作用。土壤中生物硅的含量与距离河道和海岸的长度均呈负相关关系,在生物硅的"距离效应"中海洋的作用较为显著。湿地表层土壤中植硅体的形态丰富,在黄河沿岸分别以哑铃形或突起棒形为主要植硅体形态,这与其植被特点有关;在II区域则主要以平滑棒形为主,且硅藻对生物硅的贡献比例明显增加。I区大部分站位发现的硅藻为圆筛藻,而在II区发现的硅藻主要为月形藻和舟形藻(羽纹硅藻纲),这与湿地水陆相互作用有关。植硅体主要来源于本地植物,是土壤中生物硅的最主要贡献者,同时黄河泥沙携带的来自上游流域的植硅体也对湿地生物硅含量和组成有一定的贡献。黄河口湿地土壤中生物硅的含量和组成受到河流和海洋的共同影响,具有一定的区域特性,并可能对河流和海洋硅循环产生重大影响。     

土壤植硅体碳积累潜力影响因素分析

土壤植硅体封存有机碳(phytolith-occluded organic carbon,PhytOC)是植物在地质历史时期固碳的重要形式之一,不同植物、不同器官、不同组织、不同生长时期的植硅体形态、含量、大小、分布、组合有所不同。土壤中植硅体碳积累潜力主要受气候变化、植物生产力、植硅体固碳效率、植硅体碳稳定性、土地利用方式、农艺措施、国家宏观政策等因素的影响。本文对各因素进行了较深入的分析。同时指出,固碳机理、植硅体固碳高效品种选育、人为干扰下农林生态系统植硅体碳循环过程为今后植硅体碳汇研究的重点。     

野生型水稻及其低硅突变体中植硅体和植硅体碳的含量与分布特征

【目的】水稻是典型的富硅植物,植硅体沉积在水稻体内可封存有机碳。本文分析不同吸硅能力基因型水稻植硅体含量、形态、分布及其固碳特征,探究水稻植硅体固碳机理。【方法】盆栽试验在浙江大学玻璃房内进行。供试材料为水稻低硅突变体Lsi1和Lsi2及其野生型,所有施肥和管理措施一致。于成熟期,取水稻地上部茎、叶、鞘样品,常规方法测定硅、植硅体、植硅体碳含量。【结果】1)不同基因型水稻体内硅含量、植硅体含量、生物量干物质植硅体碳含量存在显著差异,均表现为突变体显著低于其野生型,大小依次为Lsi1野生型> Lsi2野生型> Lsi2突变体> Lsi1突变体,Lsi1和Lsi2突变体水稻植硅体碳含量显著高于其野生型,大小依次为Lsi1突变体> Lsi2突变体> Lsi2野生型> Lsi1野生型。2)野生型水稻硅与植硅体含量为鞘>叶>茎,而突变体水稻硅与植硅体含量为叶>鞘>茎,水稻叶片中的植硅体碳与生物量干物质植硅体碳含量最高,植硅体碳含量整体分布趋势为叶>茎>鞘,生物量干物质植硅体碳含量整体变化趋势为叶>鞘>茎。3)水稻植硅体含量与硅含量之间呈极显著正相关(P <0.01),高吸硅的水稻植硅体含量高,且形成的植硅体比表面积小,表明植硅体含量及其形态受其遗传特性的影响。植硅体含量与生物量干物质植硅体碳含量之间呈极显著正相关(P <0.01),植硅体碳含量与生物量干物质植硅体碳含量之间呈极显著负相关(P <0.01),表明生物量干物质植硅体碳含量除了受植硅体含量影响,还受植硅体所包裹的有机碳浓度影响。4) Lsi1及Lsi2野生型水稻生物量、植硅体储量、植硅体碳储量显著高于其突变体。【结论】具有高吸硅能力的野生型水稻与其突变体相比,生物量、硅、植硅体、生物量干物质植硅体碳含量增加,分布不同,虽然植硅体碳含量降低,但植硅体碳储量增加。Lsi1及Lsi2野生型水稻比低硅突变体水稻具有更高的固碳潜力。     

温度对钼蓝比色法测定植物样品中硅的影响

钼蓝比色法是常用的测硅方法,但其测定结果受温度影响很大。本试验以硅的标准植物样—灌木枝叶为试材,样品在瓷坩埚中灰化后,用氢氟酸浸提,采用钼蓝比色法在811nm波长下测定硅的含量。显色温度设为15℃、25℃、30℃、35℃,显色时间分别为10min、20min、40min、60min和120min,研究不同温度和显色时间对硅测定结果的影响。结果表明,温度显著影响显色反应的速度,15℃显色20min时,测定值才接近标准值,高于15℃显色时间加快,显色10min测定值即达到标准值。温度同样影响显色稳定时间,在30℃和35℃放置40min时测定值已显著低于标准值,相反在15℃和25℃时,即使保持2小时对硅的测定仍没影响,且测定结果准确性较高。结果表明在本实验条件下,可以在25℃下进行大批量植物样品的测定。     

水稻秸秆中硅体的光催化活性研究

采用干燥-灼烧-煅烧工艺从水稻秸秆中制备硅体,并对硅体进行表征和光催化活性研究。结果表明,制备的硅体由无定形的微米、纳米二氧化硅颗粒组成,并具有光驱类脱氢酶活性和光催化降解甲基紫的能力。在模拟的光源下,在人工模拟的光源下,硅体催化红四氮唑(TTC)迅速转变成不溶于水的三苯甲簪(TPF),硅体的光驱类脱氢酶活力值达到2622μg TPF ·g-1 ·min-1;光催化降解甲基紫染料的结果表明硅体对甲基紫的去除率2 h内达到94.4%。秸秆中硅体的光催化特性为生物质资源的开发利用提供新途径,同时也对自然界中生物材料结构与功能的研究提供了新的思路。     

喷施硅肥对茶树生长及硅素分布的影响

【目的】研究喷施硅肥对茶树生长和茶叶品质的影响,以及硅在茶树中的累积和分布,为优质安全茶叶生产提供依据。【方法】采用室内盆栽与田间试验相结合的方法,供试硅肥为硅酸钠(Na2SiO3·9H2O)。室内盆栽试验设置7个硅喷施浓度：0、50、150、300、500、750、1500 mg/L,每7天喷施一次,共喷施3次。通过测定茶苗生物量、SPAD值、叶绿素荧光特性、植保素含量及气孔特性,以确定最佳喷施硅肥浓度。然后,以该最佳喷施浓度进行室内茶苗盆栽和田间试验,在室内试验中测定了茶苗不同部位和组织的硅含量,在田间试验中测定了茶园春、夏、秋季茶叶产量及新梢品质成分。【结果】喷施硅300、500 mg/L处理的茶苗地上部和根部生物量高于其他处理,幼苗叶绿素含量、叶片光化学猝灭系数(qP)、非光化学荧光淬灭系数(qNP)、表观电子传递速率(ETR)及植保素含量也高于Si0和其他处理,综合茶苗生长和生理指标结果,选用500 mg/L作为最佳硅喷施浓度。第一次喷施硅肥7天后,硅主要积累在叶部,从顶芽往下数的不同叶位硅含量分布为第3叶>第5叶>第1叶;第三次喷施7天后,第5叶硅含量显著高于第...     

航天搭载对硅链霉菌菌株生理生化特性的影响

研究航天搭载对硅链霉菌菌株生理生化特性的影响。通过神舟九号飞船搭载硅链霉菌进行实验,对航天诱变菌株的生理生化特性进行分析,为我国微生物肥料行业整体的技术进步奠定基础。结果表明:(1)搭载诱变菌株和CK菌株可以利用10种碳源,也可以利用10种氮源;(2)搭载诱变菌株和CK菌株都可以水解淀粉,但都不产生H2S;(3)在4～45℃条件下,搭载诱变菌株与CK菌株均可以生长,并且生长状况差异不显著;但在55℃条件下,2种菌株均不能生长;(4)搭载诱变菌株在pH=6～10条件下生长良好,而CK菌株在pH为7、8、9条件下生长良好。搭载诱变菌株和CK菌株相比较,在碳源利用、氮源利用、水解淀粉、不产生H2S和温度耐受方面均无明显差别,表现出相似性,但在耐pH方面,与CK菌株相比,搭载诱变菌株生长的pH范围更广,有更好的耐受性,显示了搭载诱变菌株具有更强的抗逆性。     

不同吸硅型植物各器官硅素及氮、磷、钾素分布特征

通过采集浙江省不同生态地区玉米、黄瓜、冬瓜和番茄植株,研究不同吸硅型植物各器官硅含量分布特征及其与大量营养元素氮、磷、钾的关系。结果表明,喜硅植物玉米和不喜硅植物黄瓜、冬瓜不同器官硅含量均分别满足"末端分布规律",即从根到茎叶呈现逐渐增加的趋势;喜硅植物根、茎、叶中硅含量显著大于不喜硅植物,且各器官之间差异显著。喜硅植物叶片硅含量最高,种子中硅含量最低,表明大量硅可能以沉淀硅形态积累在茎叶中,导致其向生殖器官的转移受到抑制。不同吸硅型植物氮、磷含量在果实、茎叶中的累积较根中显著提高。喜硅植物各器官氮、钾含量与其硅含量呈一定的相关性,其含量变化呈现叶>茎>根的趋势。且喜硅植物不同器官硅含量受生长环境、土壤有效硅含量影响差异显著。     

白洋淀芦苇湿地生态系统中植硅体的产生和积累研究

植硅体(phytoliths),又称植物蛋白石,存在于大部分植物组织细胞中,主要是依靠植物的根系吸取土壤溶液中的可溶性二氧化硅,在植物细胞或细胞内沉淀硅化而形成的一种固体的非晶质含水二氧化硅颗粒物[1].植硅体主要组成部分是二氧化硅(67％～95％)、水(1％～12％)、碳(0.1％～6％)及少量的无机元素Na、K、 Ca、 Fe、 AL、 Ti等[2],由于其具有较强的抗分解、抗腐蚀和耐高温等特性,可以长时间较稳定地保存在一些岩石和土壤中[3-5],在硅的生物地球化学循环中有着重要的作用,是全球硅循环的重要参与者[6].虽然植硅体作为生物硅的重要组成部分,在全球硅的生物地球化学循环中占据着重要地位,但在湿地生态系统中植硅体产生和积累研究则鲜见报道[7].     

中国不同生态系统土壤硅的研究进展

硅是土壤和岩石的一种基本成分,具有促进植物的生长、增强植物抗性、参与生物地球化学循环过程、调节全球碳循环和缓解全球气候变暖趋势等方面的作用.本文在全面介绍土壤硅的形态、有效性及生物循环特征基础上,分析了我国不同生态系统中土壤硅及植硅体含量状况,阐明了影响土壤有效硅及植硅体的因素,重点阐述了近年来有关稻田土壤有效硅与水稻...     

电感耦合等离子体原子发射光谱(ICP-AES)测定土壤中有效硅

利用ICP-AES测定土壤中有效硅含量,经分析可得出ICP-AES测得的数据在精确度和准确度上均能满足实验的要求;说明ICP-AES可以作为一种快速、简捷的测试手段。     

Establishing Soil Silicon Test Procedure and Critical Silicon Level for Rice in Louisiana Soils

Calibration of crop responses to applied silicon (Si) serves as a basis for developing Si fertilizer recommendation guidelines. A greenhouse experiment was set up in a randomized complete block design with five replications, two sources of Si (wollastonite and slag) and four Si rates (0, 170, 340 and 680 kg ha^?1) to calibrate plant-available Si for growing rice in Louisiana soils. Silicon concentrations were determined in soils using seven different extraction procedures. Based on a quadratic model (p < 0.05), the estimated soil Si critical level using 0.01 M calcium chloride (CaCl₂) for Sharkey clay soil was 110 mg kg^?1 while for Crowley silt loam and Commerce silt loam, levels were 37 and 43 mg kg^?1, respectively. These results suggest that suitability of an extractant that gives the best estimate of plant-available Si could considerably depend on soil type and it is unlikely that there is a universal extractant for all soils.     

Silicon alleviates mercury toxicity in garlic plants

Abstract

Silicon (Si) can increase plant stress tolerance. Mercury (Hg) is one of the major elements of heavy metal pollution. However, little attention has been paid to the possible effect of Si on Hg toxicity in plants. Here, the effects of Si on growth, photosynthesis, Hg accumulation and antioxidant defense were investigated in garlic grown in pots under Hg stress. Before sowing, Hg and Si were added at 3?mg Kg^?1 and 500?mg Kg^?1, respectively. The treatments included CT (control), Si, Hg and Hg?+?Si. The results showed that in non-stress conditions, added Si did not affect the garlic growth, photosynthetic gas exchange, malonaldehyde concentration or activities of antioxidant enzymes in leaves, except that it increased the superoxide dismutase activity. Under Hg stress, the garlic growth, leaf net photosynthetic rate, stomatal conductance, transpirational rate and superoxide dismutase activity in leaves were all inhibited, while the malondialdehyde concentration was increased; whereas these changes were all reversed in the presence of added Si. Added Si significantly decreased Hg concentrations in the root, bulb and shoot, and it also decreased exchangeable Hg level in the soil. These results suggest that Si could alleviate Hg toxicity in garlic through improving antioxidant defense ability, and decreasing Hg availability in soil and thus Hg uptake.     

叶面喷施硅调理剂对水稻砷累积及其赋存形态的影响

采用营养液培养生物学模拟方法,研究了喷施8种不同的叶面硅调理剂对苗期水稻累积总砷(As)和砷形态的影响。结果表明,叶面施用硅调理剂可降低水稻根和茎叶中砷含量,其中叶面施用Na2SiO3+鼠李糖脂处理(Si6)的水稻根系和地上部砷含量最低,分别为10.04,0.31mg/kg,比对照降低25.35%和33.10%(P<0.05);水稻中砷的赋存形态主要为As(Ⅲ),喷施该叶面硅调理剂减少水稻地上部和根系As(Ⅲ)含量,降幅分别为27.74%和21.50%(P<0.05);综合考虑水稻根系和地上部砷累积及砷由根系向地上部的转运,对不同的叶面硅调理剂处理进行聚类分析发现,喷施Na2SiO3+鼠李糖脂的处理为水稻砷低积累类群。因此,生物表面活性剂鼠李糖脂与含硅溶液配施是抑制水稻幼苗吸收和积累砷效果最好的叶面硅调理剂,可为我国砷污染区稻米生产安全提供技术支撑。     

Silicon fractions in Histosols and Gleysols of a temperate grassland site

The importance of silicon (Si) in nutrition is currently being recognized by its beneficial effects on many crops. Therefore, it is important to determine the soil Si status and to examine different extractants for testing plant‐available Si. Little information is available about the Si status of Histosols and C_org‐rich Gleysols in temperate climate. This study was undertaken (1) to characterize different Si pools in C_org‐rich groundwater soils of an experimental site and (2) to study the influences of small‐scale variability on element distribution. At the experimental site, the thickness of the C_org‐rich layer ranges between 4 and 5 dm overlying fine‐sandy fluvial sediments. Four extractants were evaluated: 0.01 M CaCl₂, 0.5 M acetic acid, 0.1 M sodium pyrophosphate, and 0.1 M Tiron (C₆H₄Na₂O₈S₂ · H₂O). Further, total element content was determined following HNO₃/HF digestion. Calcium chloride–soluble Si shows no significant relations to other parameters analyzed. On the basis of published data, the soils investigated could be classified as Si‐deficient. The Si fraction extracted with acetic acid displays relations to C_org content of the soil and a weak correlation to CaCl₂‐soluble Si, indicating that both solutions extract overlapping but not the same fractions. Sodium pyrophosphate extracts mainly organo‐mineral Fe and Al complexes in the soils studied, which is reflected in a highly positive correlation to C_org. Pyrophosphate‐soluble Si showed a negative relationship to C_org, which means a closer relation of this Si fraction to mineral matter than to C_org. The Tiron solution extracted most Si of all extractants, but this amounts only 1% of the total Si content. Taking into account the element‐specific relationship between pyrophosphate and Tiron‐extractable Fe, Al, and Si, it can be concluded that Tiron dissolves mainly the opaline silica present in Histosols and C_org‐rich Gleysols. The distribution of C_org and ash content shows clear spatial trend at the experimental site, which is correlated to pyrophosphate‐extractable as well as total Si. This small‐scale variability of soil parameters itself is related to a distinct microrelief.     

Simple,Robust Method for Quantifying Silicon in Plant Tissue

Low silicon (Si) content in rice, sugarcane and other Si-accumulating crops can adversely affect crop performance because it creates reduced tolerance to both abiotic and biotic stresses. Assessing the Si status of a crop typically depends upon accurately measuring Si accumulation in plant tissue. Methods involving wet digestion of plant tissue followed by colorimetric determination of Si have proven attractive because they are both rapid and do not require costly, specialized instrumentation. Some popular wet-digestion methods are reported to provide highly variable and inconsistent results. A systematic study to identify and address the sources of variability associated with wet digestion for Si analysis found that modifications that reduce excessive foaming during wet digestion of plant tissue in strong alkali and peroxide significantly reduce variability. Unstable and variable color development associated with the molybdenum blue reaction is a concern in the colorimetric determination of Si in digests. Experiments showed that the inclusion of ammonium fluoride to facilitate the release of polysilicic acid prior to colorimetric determination results in reproducible readings that stabilize within 60 min and remain stable for at least 5 h. With this modification, the accuracy and precision of values obtained colorimetrically are comparable or superior to those obtained by inductively coupled plasma–optical emission spectroscopy (ICP-OES) analysis. A two-phase wet-digestion procedure is described for Si tissue analysis that is robust, accurate, and precise and requires equipment commonly found in most agricultural laboratories.     

Silicon concentrations in soil and bark in Irish Sitka spruce forests

The relationship between plant‐available silicon (Si) soil concentrations and bark Si concentrations in coniferous species is poorly understood. The objectives of this research were to generate baseline data on Si concentrations in soils and bark of Sitka spruce (Picea sitchensis) seedlings in Ireland and to understand better the relationship between soil and bark Si concentrations. Seedlings were harvested from eight plantation forestry sites and two tree nurseries, and Si concentrations in the bark tissue as well as plant‐available Si concentrations in soils (CaCl₂ extractant) were measured. Bark Si concentrations varied significantly between sites and were lowest [mean 790 (± 242 SD) mg kg^?1 dry plant tissue] on acidic, organic rich peat soils, while the highest Si concentrations occurred in seedlings [mean 3688 (± 633 SD) mg kg^?1 dry plant tissue] grown on soils with low C concentration and higher pH values (≈ 4.5 to 5.5 in H₂O). Plant‐available Si soil concentrations were not related to soil C concentrations. There was a negative (but statistically not significant) relationship between plant–soil concentrations and soil pH. A significant negative relationship was observed between plant‐available soil Si concentrations and bark Si concentrations, which may be related to the presence of soil from mixed soil horizons forming the mounds that seedlings were planted on. Uptake and sequestration of Si by seedlings may have been related to the rate of growth of the seedlings, as bark Si concentrations were highest on sites that were expected to have greater seedling growth rates. The negative relationship between bark and plant‐available Si soil concentrations suggest that uptake of Si by Sitka spruce is rejective at higher concentrations.     

Influence of Silicon on Growth,Relative Water Contents and Uptake of Silicon,Calcium and Potassium in Wheat Grown in Nutrient Solution

Growth performance, relative water contents (RWC), and mineral nutrition were studied in Triticum aestivum L. treated with different concentrations of silicon (25, 50, 100, 200, 400 and 800 ppm). Lower administrations of silicon (25–200 ppm) resulted in an enhancement in relative yield, relative water contents, calcium, and potassium contents. A significant (0.1% level) direct relationship between tissue silicon content and applied silicon concentrations and an inverse relationship between relative yield and higher applied silicon concentrations (400 and 800 ppm) were observed. Shoots were significantly richer in silicon content than roots. The results indicate a possible requirement of silicon for higher plants.     

陕西省耕地土壤有效硅分布规律初探

在陕西省17种土壤类型中,选取了其中分布面积较广且具有代表性的11种耕地土壤类型,共采集耕层土壤样品159个,利用柠檬酸浸提法分析土样中的有效硅含量。结果表明,陕西省土壤有效硅平均含量为390.99mg/kg,最高为980.32 mg/kg,最低为74.5 mg/kg;土壤有效硅的水平分布特征总体上呈现北低南高,在陕南地区呈现西高东低的特征。土壤有效硅含量与土壤有机质、土壤全氮、全磷的含量成正比关系,与土壤全钾的含量关系不明显。