明胶对土壤微生物数量及矿质氮含量的影响

考察了不同浓度的明胶对不同土壤微生物数量及矿质N的影响．将0％,0．1％,0．2％,0．5％,1．0％,1．5％的明胶分别添加入土壤中,分别于第3,7,14,24,34,44,54,64天采取土样分析其微生物种群数量和氮营养水平变化．结果表明：随着明胶量的增加,土壤中三大类微生物的数量及硝态氮和铵态氮的含量均增加,但随着时间增长,有恢复原有水平的趋势．以培养采样时间为横轴。各测量指标为纵轴得到的趋势曲线表明,数量的拐点：细菌在24天,真菌34天,园艺土放线菌44天、菜地土放线菌34天．前期显著增加了对细菌和真菌的数量,后期显著增加了放线菌数量;硝态氮的拐点：园艺土在54天,菜地土在44天;氨态氮的拐点随明胶浓度的不同表现不太一致,但都在第14天后恢复．土壤微生物学特性及N营养水平的变化反映出：在控制范围内,明胶量的增加,提高了土壤健康的生物指标及营养指标．     

重金属对香蕉生长影响的试验研究

对香蕉园土壤与灌溉水添加Cd、Hg、As、Pb、cr、cu重金属元素,研究该重金元素对香蕉生长影响,以及香蕉叶片对该重金元素的富集能力。结果表明：当重金属的浓度累集到一定值时,会对香蕉的生长发育产生抑制作用,浓度太高会造成香蕉的生长停滞甚至死亡。随着土壤中Pb、Cd、As、Hg、cr、Cu重金属含量的增加,香蕉叶片中富集的重金属含量和富集系数表现为正相关的递增,香蕉叶片富集系数为Cr〉Cd〉Hg〉As〉Cu〉Pb,重金属的添加量与香蕉叶片体内含量的相关系数（r）分别为0．9630～0．9994、0．9128～0．9983。     

学科实践是发展生物学科核心素养的重要途经——以“探究海拔高度对南京紫金山土壤微生物功能的影响”为例

以南京紫金山不同海拔高度的土壤为研究对象,探究了土壤理化性质、土壤微生物生物量和土壤酶活性对海拔高度变化的响应。实验结果表明：随着海拔升高,土壤含水量和pH显著降低;土壤有机碳、总氮和总磷均随海拔升高而显著增加,而土壤速效养分如DOC、有效氮和有效磷以及土壤微生物生物量碳、微生物生物量氮和微生物生物量磷则随着海拔的升高而显著降低;土壤碳分解酶、氮分解酶和磷分解酶也随着海拔升高而活性降低。研究表明,土壤微生物生物量和土壤酶活性对海拔升高反应敏感,随着海拔高度增加,土壤含水量和温度的降低影响了微生物和酶的活性,使得土壤有机质分解缓慢,积累较多;而在低海拔处土壤酶活性较强,土壤有机质分解迅速,土壤有效养分含量提高。     

杂草五爪金龙对其入侵地土壤酶活性与微生物群落的影响

五爪金龙是粤东地区入侵性极强的外来杂草,其对入侵地土壤生态系统可能存在明显的改造作用．在野外调查的基础上,确定3个被五爪金龙重度入侵的生境作为采样地,通过室内实验测定与分析五爪金龙对入侵地土壤酶活性、土壤微生物群落的影响．结果表明：与非入侵地比较,杂草五爪金龙种群在粤东地区的入侵明显改变了入侵地的土壤生态系统的部分结构与功能,包括显著提高了入侵地土壤中蔗糖酶、脲酶、磷酸酶及硝酸还原酶的活性,其提高幅度均在2倍以上;增加了真菌、自生固氮菌及氨氧化细菌的数量,降低了细菌与反硝化细菌的数量,其改变率均大于20％．土壤酶活性与土壤微生物群落的改变可能导致土壤肥力的变化,因此,五爪金龙成功入侵的土壤微生物学机制有待进一步探讨．     

不同土壤条件对蕹菜典型品种种子萌发和生长的影响

通过盆栽试验,研究了不同土壤条件对4个蕹菜Cd积累典型品种的种子萌发和生长特性的影响．结果显示品种和土壤对发芽率、株高和生物量的效应均极显著（P〈0．01）．各品种种子平均发芽率依次为T308〉QLB〉GDB〉QLQ,各土壤上依次为F〉A〉E〉C〉D〉B．各品种第一茬平均株高依次为T308〉QLB〉GDB〉QLQ;第二茬依次为T308〉GDB〉QLB〉QLQ．各土壤第一茬平均株高依次为D〉A〉E〉B〉C〉F,第二茬依次为A〉B〉C〉E〉D〉F．各品种平均生物量依次为GDB〉T308〉QLB〉QLQ．各土壤上平均生物量依次为A〉C〉E〉B〉D〉F．结果表明蕹菜Cd积累典型品种的发芽和生长在不同土壤上呈现一定的稳定性,相关分析表明其生长特性与土壤EC、速效P、有效Pb含量等土壤因子相关．     

长期氮添加对兴安落叶松林植物病原菌群落结构的影响

植物病原菌在生态系统功能中发挥重要作用。但在全球变化背景下,长期氮沉降如何影响植物病原菌群落尚未得到充分研究。因此,在大兴安岭兴安落叶松林进行了原位氮添加试验,共设置了4个氮添加梯度。2021年7月,采集了土壤、植物根系和叶片样品。利用16SrRNA和18SrRNA测序技术,探讨氮添加对土壤和植物共生病原菌群落的影响及其潜在机制。结果表明：氮添加显著增加了叶片细菌和真菌病原菌多样性,降低了土壤细菌病原菌多样性;氮添加引起根际和根系内生真菌病原菌群落结构发生了显著变化,但未显著改变土壤、根系和叶片细菌病原菌群落结构。冗余分析表明,土壤pH、NO^-₃-N、MBN和MBC是影响土壤和植物细菌和真菌病原菌群落结构的重要环境因子。基于上述,氮添加可能通过改变土壤性质,进而影响土壤和植物病原菌群落结构。     

冬种绿肥对水稻黄泥田脲酶活性的影响

作者讨论了冬种绿肥对黄泥田中脲酶活性的影响，冬种绿肥对土壤农化性状的影响，及脲酶活性与土壤农化性状的关系，得出结果表明，冬种绿肥能提高脲酶活性及其它土壤农化性状和水稻产量．     

土壤石油污染对两种藜科植物幼苗生长的影响

在实验室人工控制条件下,研究了不同浓度土壤石油污染对两种藜科植物幼苗生长的影响。实验结果表明：土壤石油污染质量分数为500—5000mg／kg时,对碱蓬幼苗株高的生长有一定的促进作用,土壤石油污染质量分数在15000～30000mg／kg时有显著的抑制作用;任何浓度的土壤石油污染都会抑制翅碱蓬幼苗株高的生长,随着石油浓度的逐级增加,抑制作用逐级增大。     

酸性土壤中铝的活化及其对植物生长的影响

本文综述了酸雨对酸性土壤性质的影响及由此产生的对植物生长的影响。酸雨pH值越低 ,我国南方酸性土壤酸化越严重 ,土壤中盐基离子淋失量越大 ,铝的活化量也越大。土壤中盐基离子大量淋失 ,造成植物必要养分缺乏 ;铝的活化能够对植物产生毒害 ,影响植物的正常生长 ,甚至引起植物的死亡     

中国最新植被恢复技术“高次团粒”正式通过鉴定

<正> 中新网2007年11月19日消息:中国最新植被恢复与环境生态性防护技术——"高次团粒"今天正式在京通过国家建设部组织的成果鉴定,并列为2007年全国建设行业科技成果推广项目。据介绍,此项新技术是针对植物在自然条件下生长困难的地方,比如岩质和土质边坡、瘠薄地、酸碱性土壤、干旱地带、海岸堤坝等,采用经特殊生产工艺制成的客土材料,加入植物的种子,并添加许多必要的其他材料,通过专业设备制成最适于植物生长的生育基盘。该种"人工土壤"具有农业、绿化领域所需最     

Preschool Children's Explanations of Plant Growth and Rain Formation: A Comparative Analysis

This paper explores the different types and characteristics of preschool children's explanations of plant growth and rain formation. The children's explanations were categorized as naturalistic, non-naturalistic, or synthetic, i.e., explanations containing both naturalistic and non-naturalistic parts. In regards to plant growth the children tended to rely on synthetic or on naturalistic explanations, which involved direct and indirect agents (such as water, a person, fertilizers, roots) enabling the plant to grow. Non-naturalistic explanations of plant growth, or the non-naturalistic parts of synthetic explanations, were mainly animistic (anthropomorphic). In the case of rain formation the children most frequently used non-naturalistic explanations, which were mainly teleological or metaphysical. The naturalistic explanations recorded on rain formation, as well as the naturalistic parts of synthetic explanations tended to have a non-agentive character, i.e., children considered rainwater as preexisting in containers such as the clouds. Overall, the explanations recorded about plant growth tended to be more complex than the ones for rain formation. It is suggested that science activities designed for preschool children should take into account the types and characteristics of their explanations in order to select which phenomena are appropriate for this age group, and aim at fostering the children's ability at formulating naturalistic explanations.     

Fertilization increases paddy soil organic carbon density

Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC.     

Review:Mycorrhizoremediation—an enhanced form of phytoremediation

INTRODUCTION Biosphere pollution by heavy metals and nu-cleotides was accelerated dramatically during the last few decades due to mining, smelting, manufacturing, treatment of agricultural soils with agro-chemicals and soil sludge, etc. Problems associated with the contamination of soil and water such as animal wel-fare, health, fatalities and disruptions of natural eco-systems are well documented (He et al., 2005). Heavy metals such as Pb, Cr, As, Cu, Cd, and Hg, being added to our so…     

Mycorrhizoremediation an enhanced form of phytoremediation

Study of plant roots and the diversity of soil micro biota, such as bacteria, fungi and microfauna associated with them, is important for understanding the ecological complexities between diverse plants, microbes, soil and climates and their role in phytoremediation of contaminated soils. The arbuscular mycorrhizal fungi （AMF） are universal and ubiquitous rhizosphere mi- croflora forming symbiosis with plant roots and acting as biofertilizers, bioprotactants, and biodegraders. In addition to AMF, soils also contain various antagonistic and beneficial bacteria such as root pathogens, plant growth promoting rhizobacteria including free-living and symbiotic N-fixers, and mycorrhiza helping bacteria. Their potential role in phytoremediation of heavy metal （HM） contaminated soils and water is becoming evident although there is need to completely understand the ecological complexities of the plant-microbe-soil interactions and their better exploitation as consortia in remediation strategies employed for contaminated soils. These multitrophic root microbial associations deserve multi-disciplinary investigations using molecular, biochemical, and physiological techniques. Ecosystem restoration of heavy metal contaminated soils practices need to incorporate microbial biotechnology research and development. This review highlights the ecological complexity and diversity of plant-microbe-soil combinations, particularly AM and provides an overview on the recent developments in this area. It also discusses the role AMF play in phytorestoration of HM contaminated soils, i.e. mycorrhizoremediation.     

Yield and quality responses of citrus （Citrus reticulate） and tea （Podocarpusfleuryi Hickel.） to compound fertilizers

Experiments were carried out with citrus （Citrus reticulate） and tea （Podocarpus fleuryi Hickel.） to study the effects of compound fertilizers on their yields and quality. In the citrus experiment, application of compound fertilizers increased available P K and Mg contents in soil but decreased alkali-hydrolyzable N contents in soil and N, P and K contents in leaves. In the tea experiment, application of compound fertilizers increased available P, K and Mg contents in soil and N, P, K and Mg contents in leaves but decreased alkali-hydrolyzable N in soil compared with the urea treatment. Application of compound fertilizers could improve the quality of citrus and tea, increase their yields and enhance their economical profits significantly. Compared with the control, application of compound fertilizers increased citrus yields by 6.31, 12.94 and 17.69 t/ha, and those of tea by 0.51,0.86 and 1.30 t/ha, respectively. Correspondingly, profits were increased by 21.4% to 61.1% for citrus and by 10.0% to 15.7% for tea. Optimal rates of compound fertilizers were recommended for both crops.     

长期施用含硫化肥对水稻土化学性质和水稻吸收微量元素的影响

已持续26年的湖南祁阳红壤站长期肥料试验分三个处理:NH4C1 KCl KH2PO4;尿素 KCl 过磷酸钙;(NH4)2SO4 K2SO4 过磷酸钙.其土壤、水稻植株样品被用来研究长期施用含硫化肥对水稻土酸化、SO42--S在土壤中累积、土壤-水稻系统微量元素含量和水稻产量的影响.结果表明:大量(667 kg S hm-2yr-1)施用含硫化肥15年后已导致水稻土表层土壤pH明显下降.不施硫处理SO42--S逐年下降,而施硫处理SO42--S有明显累积.施用含硫化肥24年后(1998),土壤有效Cu、B、Mn及全Ca含量有增加趋势,全Fe有减少趋势,对有效Mo、Zn及总Mg似乎没有影响.长期施用含硫化肥已显著减少水稻(特别是晚稻)吸收Fe、Mo、B、Mg、Cl,并导致水稻(特别是晚稻)产量显著下降.可见,长期施用含硫化肥可能影响水稻土性质进而影响水稻生长.     

Plant Growth Promoting Rhizobacteria

Plant Growth Promoting Rhizobacteria (PGPR) are a group of bacteria that enhances plant growth and yield via various plant growth promoting substances as well as biofertilizers. Given the negative environmental impact of artificial fertilizers and their increasing costs, the use of beneficial soil microorganisms such as PGPR for sustainable and safe agriculture has increased globally during the last couple of decades. PGPR as biofertilizers are well recognized as efficient soil microbes for sustainable agriculture and hold great promise in the improvement of agriculture yields.     

土料分散特性试验研究

分散性土具有遇水分散流失的特性,容易造成堤坝等水利工程的破坏。采用双比重计、针孔、碎块、孔隙水可溶性阳离子和交换性钠离子百分比等5种试验方法,对宁夏某水电站大坝防渗土料分散性进行了研究分析,认为该防渗土料属于过渡性土。但是值得注意的是,4组土样的权重分析中分散性占的比重比较大,在设计中应注意当土样周围环境发生变化时（如河水水质）对土样分散性判别结果的影响。     

Effects of ammonium application rate on uptake of soil adsorbed amino acids by rice

In recent years, excessive use of chemical nitrogen (N) fertilizers has resulted in the accumulation of excess ammonium (NH ₄ ⁺ ) in many agricultural soils. Though rice is known as an NH ₄ ⁺ -tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH ₄ ⁺ content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH ₄ ⁺ concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils;’ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH ₄ ⁺ content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine:NH ₄ ⁺ concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%;–22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH ₄ ⁺ application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the ¹³C, ¹⁵N double labeling technology.     

Phosphate-solubilizing microbes in rhizosphere soils of 19 weeds in southeastern China

Low phosphorus (P) availability is one of the most important factors limiting plant growth in red soils across southeastern China. Many non-symbiotic microorganisms in rhizosphere can enhance P solubility, but little is known about the magnitude of their phosphorus-solubilizing ability (PSA) and the difference in phosphorus-solubilizing microorganisms (PSM) among plant species. The number of phosphorus-solubilizing microorganisms and their PSA in rhizosphere soils of 19 weed species in a citrus orchard on red soil at Changshan, Zhejiang, China, were investigated. Inorganic P (powdered phosphate rock, PR) and organic P (lecithin, OP) were respectively used as the sole P-source to examine the PSA of isolated microbes. The PS actinomycetes community varied greatly among the different weed rhizospheres while the PS fungus community showed to be most stable to the weed rhizosphere. The highest number of PR-PS and OP-PS bacteria was found in rhizosphere soil of Mollugo pentaphyll, and the highest number of PR-PS and OP-PS actinomycetes was found in rhizosphere soil of Polygonum lapathifolium. The highest number of PR-PS fungi was found in Erigeron annuus and Mollugo pentaphyll rhizosphere soil, and the highest number of OP-PS fungi was found in rhizosphere soil of Mazus stachydifolius. Mazus stachydifolius showed the strongest PR-PS ability (6340.75μg) while Eragrostis pilosa showed the strongest OP-PS ability (1301.84μg). The PR-PS ability and OP-PS ability of Mollugo pentaphyll was 4432.87μg and 1122.05μg respectively. A significant correlation between the number of PR-PSM and OP-PSM was found. Significant correlation was only found between the PR-PS fungi number and its PSA(r=0.75, P<0.05) and between the number of OP-PS fungi and its PSA(r=0.87, P<0.01}). It indicated that plant species had significant influence on components of the non-symbiotic PSM community and their activity in its rhizosphere soil. Fungi play a leading role in phosphorus solubilization in weed rhizopshere. It suggested that weed conservation could benefit soil microbe development in agroecosystems, especially in the initial stage of agroecosystem development because there is less organic carbon in bare soil. The results suggested that weed conservation could increase PSA of PSM.