一株克锡勒氏菌对小麦苗期的促生耐盐效应研究

土壤盐渍化已经成为全球重要的生态环境问题之一,农业生态系统中土壤盐分增加会影响作物生长发育、导致减产。近年来,随着微生物组学研究的深入,微生物提升植物抗逆性功能认识的加深,生物肥料开始应用于盐碱地植物修复中。为探究根际促生菌在高盐环境中对小麦生长及代谢的影响,本文选取一株分离自盐地碱蓬根际土中、具有耐盐和分泌植物生长素功能的克锡勒氏细菌(Kushneria indalinina JP-JH),选取耐盐小麦品种‘小偃60’,在无盐(0 mmol·L~(-1))、低盐(200 mmol·L~(-1))和高盐(400 mmol·L~(-1))的水培条件下接种耐盐促生菌JP-JH,分析其对小麦苗期生长及根系分泌有机酸的影响。培养40 d后,在无盐、低盐、高盐条件下,接种JP-JH组小麦幼苗鲜重显著高于未接种对照组(P0.05);在无盐、低盐时,接菌组的小麦幼苗干重显著高于对照组(P0.05);且在高盐胁迫时,接菌组株高显著高于对照处理(P0.05)。在无盐条件下,接菌未对小麦幼苗根系分泌的6种有机酸产生显著影响;在盐胁迫(低盐以及高盐)条件下,接菌显著提高了根系分泌草酸和酒石酸含量(P0.05)。上述结果表明耐盐促生菌能够在苗期促进小麦的生长发育,且对根系分泌的部分有机酸产生了显著影响,草酸和酒石酸可能在微生物-植物互作中具有重要作用。本研究揭示了细菌K. indalinina JP-JH对小麦的耐盐促生效应以及对根系分泌有机酸的影响,为开发具有提升小麦耐盐促生功能的生物肥料提供理论依据和菌种资源。     

转录组分析揭示了棉花根系盐胁迫调控的生物进程和主要代谢途径

高盐是限制棉花生长和生产力的主要因子。研究报道,植物响应高盐主要是由参与离子和渗透压平衡信号、解毒和生长调节等途径来控制的,同时植物对渗透胁迫的应答还影响脱落酸(ABA)的代谢和信号传导途径、盐胁迫和干旱胁迫是紧密相关的。植物遭遇盐胁迫的时候,根部是最敏感的,在受到盐胁迫的棉花幼苗中,根的长度和鲜重减少的程度远远大于子叶下胚轴。     

土壤中有机污染物的植物修复研究进展

植物修复是土壤有机污染物修复的有效途径之一，主要包括植物吸收、根际土壤酶促进降解和微生物对其的一系列降解。本文简述了植物修复的含义，系统综述了植物修复有机污染物的机理，并阐述了利用植物对农药、氯代化合物、多环芳烃和其它有机污染物进行修复的研究成果与应用，展望了今后进一步研究的重点。     

两种盐生植物在南北疆地区的适生性及吸盐能力

为了摸清盐生植物在南北疆改良盐碱地的实际应用效果,更好地利用盐碱植物,在南北疆地区进行田间试验,研究了两种盐生植物在新疆南北疆盐碱地的适应性及吸盐能力。结果表明,盐生植物在南疆的成活率明显高于北疆;而盐地碱蓬成活率明显要高于海篷子;北疆种植的盐生植物其植物体内的总含盐量明显高于南疆种植的盐生植物,其中盐地碱蓬高出约55%,海篷子高出约46%。由此可以看出,盐地碱蓬和海篷子更适合于南疆地区生长,而在北疆环境两种盐生植物吸盐能力均强于南疆环境,海蓬子吸盐能力明显强于盐地碱蓬。     

有机污染物污染土壤环境的植物修复机理

利用活的生物体对有毒有机物污染土壤环境的修复是一种被人们认为安全可靠的方法。植物修复是生物修复研究的热点。植物修复的机理包括植物对有机污染物的直接吸收、植物根系分泌物、微生物对根际环境中有机污染物降解的促进作用。     

河北省滨海盐碱地土壤与盐生植物养分特征的研究

对滨海盐碱地土壤和植物样品分析结果表明,生长不同盐生植物的土壤含盐量不同,以生长白刺(Nitraria sibirica Pall.)的土壤含盐量最高,达18.5 g/kg,盐地碱蓬(Suaeda salsa L.Pall.)次之,柽柳的最低。盐生植物的生长改变了土壤养分特征,4种生长盐生植物的土壤养分含量均高于光板地,土壤有机质含量增加44％以上,生长木本盐生植物白刺、柽柳(Tamarix chinensis Lour.)的土壤养分含量高于生长草本盐生植物碱蓬、碱茅(Puccinellia distans Jacq.Parl.)的土壤,且不同盐生植物养分特征不同,白刺、柽柳N和P含量均高于盐地碱蓬、碱茅,K含量则与植物耐盐特性有关。     

不同生境下盐生灌木盐岛效应的变化及生态学意义

为探明生境与植物种类对盐岛效应的影响,选取了分布于塔里木盆地北缘盐化草甸生境和灌丛生境的3种盐生灌木,即多枝柽柳(Tamarix ramosissima)、盐穗木(Halostachys caspica)、盐节木(Halocnemumstrobilaceum),分析了植丛下与植丛间土壤的pH、总盐和8种盐分离子含量的变化。研究结果表明在盐化草甸生境,只有盐节木植丛下的土壤盐分呈明显的富集状态,即形成了盐岛;而在灌丛生境,3种盐生植物均具有明显的盐岛效应,且盐岛效应以盐节木最高,多枝柽柳最低。数据分析进一步表明盐岛效应的强弱受植物种类和所处生境的影响:即分布于高盐环境的盐生植物和耐盐能力强的植物盐岛效应更为明显。而生境变化和植物种类的不同,对盐岛内盐分离子的富集也有不同的影响。盐岛效应的增强有加速草甸向盐生灌木为主的荒漠退化的趋势。     

土壤中铅污染及其植物修复技术综述

铅是土壤中一种常见的重金属污染物,对动植物生长及人类健康具有极大的潜在隐患,土壤中的铅不易被清除且难以被微生物分解。一些植物对重金属的耐性及积累特性对于修复土壤中铅的污染具有十分重要的作用。综述铅作为土壤重金属的危害,简述植物修复技术的优缺点。介绍植物修复技术之一——草坪草的修复作用,草坪草作为修复植物的优劣,草坪草作为修复植物的应用情况。结合国内外的实际情况,对未来重金属污染中植物修复技术的发展趋势作了展望。     

植物和微生物修复石油污染土壤的研究进展

阐述了植物和微生物降解环境中石油污染物及PAHs的重要作用和最新进展。国内外大量实验室研究表明,不同植物和微生物(细菌、真菌和放线菌)联合修复石油污染土壤均得到了较为理想的效果,在某种程度上微生物菌群要优于单一菌株;土壤中植物根系与微生物形成根际效应对污染物的降解起到了促进作用;生物表面活性剂较合成表面活性剂具有更好的生态适宜性和石油污染土壤修复能力;土壤中多组分污染物共同修复虽处于起步阶段,其作用机理也有待进一步研究,但是,发展前景值得期待。目前该领域的研究仍存在一些问题有待解决:植物–微生物菌群降解石油污染物过程中,微生物菌群间协同和竞争机制及试验结果的可重复性尚需证实;实验室研究与大田环境条件的差异,使得目前的研究成果尚需田间试验的验证和支持;根据土壤类型和气候特点,研究极端(高含盐量;氮、磷等营养元素缺乏;低温)条件下的石油高效降解菌株/群,制备有效的便于大田应用的固体菌肥意义重大;同时在确定石油污染物对环境致害的限值的基础上,建立石油污染土壤评价体系也势在必行。     

解磷微生物及其在盐碱土中的应用研究进展

解磷微生物能够将土壤中难溶性磷酸盐转化为可供植物吸收利用的磷，在提高土壤有效磷含量、缓解植物盐碱胁迫损伤及修复盐碱土中表现出良好的应用前景。本文从解磷微生物的研究及应用现状入手，综述了盐碱土中解磷微生物的分离、解磷机制，同时阐述了盐碱耐受性和解磷能力关系及其在盐碱土修复中的应用进展，以期为利用耐盐碱解磷菌缓解植物盐胁迫损伤及修复盐碱土提供重要参考。     

复垦土壤盐分污染的微波频谱分析

复垦工程完成后，复垦土壤的结构、层次等受到破坏，易发生盐碱化，微波的穿透性为土地质量的监测提供可能。该试验通过对复垦土壤在不同水分条件下，不同盐分污染程度的探地雷达探测，旨在揭示盐分污染下，微波信号的变化规律。结果表明：中心频率为400 MHz的天线在不同程度的盐分污染下，主频发生偏移，出现在250 MHz。随着盐分污染的加重，出现双峰现象，次主频出现在530 MHz，且随着盐分污染的加重次主频的相对振幅逐渐加强，不同的水分含量系列下，出现相同的现象。由于探地雷达可以快速、大面积的无损探测，因此，能够及时提供复垦土壤盐分变化的信息，可以对复垦土地的质量实时监测、及时治理。     

宁夏引黄灌区日光温室集约种植区浅层地下水硝态氮含量与耕层土壤硝态氮含量的关系

  目的  探讨宁夏引黄灌区日光温室集约种植区地下水硝态氮污染现状及其与土壤硝态氮含量之间的关系,为有效防治地下水硝态氮污染及土壤盐渍化提供理论依据。  方法  通过抽样调查方法,采集7个典型日光温室集约种植区不同时期的214个地下水样及102个0 ~ 20 cm土壤样品,分析了地下水和土壤的硝态氮含量及电导率等。  结果  地下水样本硝态氮含量超过Ⅲ类水标准的达53.3%;近80%的土壤样本呈现出不同程度的盐渍化,其中中度盐化土占57%。当地下水硝态氮含量大于40 mg L?1时,地下水电导率、土壤电导率和土壤硝态氮含量均随地下水硝态氮浓度增加而急剧增加。土壤电导率与土壤硝态氮含量之间呈极显著线性函数关系,决定系数达0.376。土壤硝态氮含量与地下水硝态氮含量之间呈极显著的指数函数关系,土壤电导率与地下水电导率之间呈极显著的线性函数关系。  结论  宁夏典型日光温室集约种植区的地下水硝态氮污染和次生盐渍化严重,并与土壤硝态氮含量和盐渍化密切相关。     

黄土母质生土当年施肥对谷类作物生产力与根际土壤营养及生物活性的影响

连续3年试验研究了黄土母质生土当年施肥对谷类作物生产力与根际土壤营养及生物活性的影响。结果表明:黄土母质生土当年施肥促进了作物根系生长、生产力增加,强大的根土系统又促进了微生物的繁衍、酶活性及土壤营养的提高。黄土母质生土的熟化利用过程需用地养地相结合,重视生物改土。本研究表明,高粱、玉米均可作为生土改良沃化的先锋作物,高粱根系强壮,入土深,生物量大;而玉米虽根重、最大根长、一级节根数低于高粱,但根际土壤微生物数量多,酶活性高。而黍子根系柔弱,根际土壤生物活性较低,与高粱、玉米相比,不宜作为生土改良的先锋谷类作物。黄土母质生土对外源的辅助能(当年施肥)反应十分敏感,施肥的增产效应与土壤培肥都十分显著。黄土母质生土熟化沃化过程既是一个生土培肥改良过程,也是一个物质能量(营养)投入转化过程,并经植物物质生产过程、土壤微生物分解矿化过程及土壤生物化学酶系统促进过程三者互动,共同构成根土苗微生物物质能量转化的生态系统。     

控制排水条件下农业非点源污染物流失特征

通过在宁夏回族自治区青铜峡灌区进行的自由排水与控制排水的对比监测试验,系统分析了控制排水条件下排水量以及农田排水中盐分、总磷、硝酸盐氮、氨氮浓度和负荷的变化特征,分析了控制排水的节排减污机理。研究结果表明：相比于自由排水,控制排水在稻田生长期可累计减少排水43.01%,并降低农田排水中各类污染物浓度,盐分、总磷、硝酸盐氮、氨氮浓度分别减少7.68%、17.39%、18.16%、9.20%;农田排水中盐分、总磷、硝酸盐氮、氨氮污染负荷相应减少46.49%、44.46%、57.51%、38.89%;污染负荷的     

灌溉水盐度和施氮量对棉花产量和水氮利用的影响

淡水资源不足和盐渍化是干旱半干旱地区农业生产的重要限制因素,因此提高水、 肥利用效率和作物产量,减少根区盐分积累和地下水污染风险是这些地区水分养分优化管理的重要目标。通过田间试验研究了滴灌条件下灌溉水盐度和施氮量对棉花产量和水、 氮利用率的影响。试验设置灌溉水盐度和施氮量两个因素,灌溉水盐度（电导率,EC）设3个水平,为0.35（淡水）、 4.61（微咸水）和 8.04（咸水）dS/m,分别用SF、 SM和SH表示;施氮（N）量设4个水平,为0、 240、 360和480 kg/hm2,分别以N0、 N1、 N2和N3表示。研究结果表明,棉花干物质重、 氮素吸收量和氮肥利用率受灌溉水盐度、 施氮量及二者交互作用的影响显著。咸水灌溉处理（SH）棉花干物质重、 氮素吸收量、 产量和氮肥表观利用率均显著降低,而微咸水灌溉（SM）对棉花氮素吸收量和氮肥表观利用率影响不大,但干物质重和产量有所降低。施氮肥可显著促进棉花生长,增加干物质重、 氮素吸收量和产量,但随着灌溉水盐度的增加,其促进效应明显受到抑制。微咸水和咸水灌溉会导致水分渗漏增加、 蒸散量降低,增施氮肥则可显著降低水分渗漏、 增加蒸散量。微咸水灌溉水分利用率最高,其次是淡水灌溉,咸水灌溉最低;增施氮肥则可显著提高水分利用率。因此滴灌条件下,高盐度的咸水不宜用于灌溉。而短期的微咸水灌溉不会对棉花产量和水、 氮利用率产生严重的负面影响;同时,合理的配施氮肥也有助于促进棉花生长,提高棉花产量和水分利用率。     

上海市土壤中持久性毒害污染物和盐分含量特征研究

Some farmland soils in Shanghai had high salinity levels, suggesting secondary salinization of the soils. The soil problems in Shanghai were studied, including the salinity and nitrate nitrogen (NO₃^--N) concentrations, heavy metal pollution characteristics, and organochlorine pesticide (OCP) residual levels and polycyclic aromatic hydrocarbon (PAH) contents. Accumulation of NO₃^--N in vegetable soils was the most significant among different functional soils. Heavy metal pollution was significant in the samples collected from the sewage-irrigated land and roadside. The identification of the metal sources through multivariate statistical analysis indicated that Pb, Zn, Cu and Cr in urban soils were from the traffic pollutants; excessive application of fertilizer and irrigation were the main reasons for the metal pollution in agricultural soils; Ni in the observed soils was controlled by parent soils. OCPs could still be detected in farmland soils but degraded greatly in last 20 years after prohibition of their usage. PAHs with 2-3 rings were the main components in industrial soils. The concentrated PAHs in the investigated soils were likely from petroleum and coal combustion.     

石灰性土壤施磷、铁对柠条生长及根际土壤环境的影响

采用随机区组和裂区设计,通过盆栽和根箱模拟试验研究了石灰性土壤,在水分充足的条件下施磷及磷、铁对柠条生长发育及根际土壤养分有效性的影响。盆栽试验结果表明,柠条的生物产量随着施磷水平的增加而增加;在低磷或磷胁迫条件下,柠条的地上部生长受到抑制,根冠比增大,土壤pH值迅速降低。根箱模拟试验发现,不同的铁、磷施肥配比对柠条生物产量的影响不同,当磷和铁的施用量分别为P2O50.15 g kg-1 和FeSO4·7H2O0.03g kg-1时能明显提高柠条的生物量。不同铁、磷配比对柠条根际土壤有效磷含量影响的根际范围是0-6 mm之间,在此范围内供试土壤有效磷含量随距离快速下降,并与根际土壤pH值呈反比。柠条对根际土壤pH的调控主要受磷水平的影响,而施铁水平对根际和根外土壤pH值的影响比较小。     

Evaluation of Two Techniques: mFC AND mTEC for Determining Distributions of Fecal Pollution in Small,North Carolina Tidal Creeks

Most tidal creeks in North Carolina are closed or partially closed to shellfishing. These creeks often remain closed due to the inability to determine sources of fecal pollution. This study was designed for intensive fecal coliform monitoring of Futch Creek, N.C., to try and determine sources(s) of fecal pollution. Futch Creek is a mildly polluted tidal creek, with marginal levels of fecal coliforms and could potentially be reopened. Problems in interpreting levels of fecal coliforms and pollution risks are two fold and were extremely pronounced in this study. First, several environmental factors have been shown to influence levels of fecal coliforms. Therefore, effects of temperature, salinity, tidal cycles, and rain events on fecal coliform counts were examined. There were higher fecal coliform levels in the warmer temperatures. There was a strong inverse relationship with salinity, with highest fecal coliform counts in the 10–14 g L^-1 range for both the mFC and mTEC counts with no apparent source of pollution. This trend was also observed in three other tidal creeks. Tidal cycles did affect fecal coliform counts with substantially higher counts during low tide and appeared to be more important than rain events. It is apparent that when evaluating several stations in a creek, samples must be taken during the same tidal cycle stage in order to have comparative data. Counts obtained using the mTEC method were consistently higher than mFC counts in all salinity ranges. Basic taxonomic tests were performed on fecal coliforms isolated from three salinity regimes: 0 g L^-1, 10–14 g L^-1, and 23–26 g L^-1. The mFC method in the 10–14 g L^-1 (45%) and 23–26 g L^-1 (70%) salinity range had the highest incidence of false-positive counts (non E. coli). The mTEC method also had the highest incidence of false-positive counts in the 23–26 g L^-1 (27%) and 10–14 g L^-1 (24%), none as high as the mFC method. Therefore, the mTEC method appears to be the better of the two but is still not an ideal approach.     

Effects of salinity and flooding on the infectivity of salt marsh arbuscular mycorrhizal fungi in<Emphasis Type="Italic"> Aster tripolium</Emphasis> L.

Salt marshes are characterized by the occurrence of combined salinity and flooding stresses. The individual and combined effects of salinity and flooding on the establishment and activity of arbuscular mycorrhizal (AM) colonization in the salt marsh halophyte Aster tripolium L. by indigenous salt marsh AM fungi were evaluated. A. tripolium plants were cultivated in a mixture of sand and salt marsh soil under different salinity concentrations (5%, 50% or 100% artificial seawater) and water regimes (non-flooding, tidal flooding and continuous flooding). Plants were harvested after 3 and 8 weeks and their growth was negatively influenced by increased salinity and water level. Increased salinity level affected the establishment of AM colonization, AM fungal growth and activity (measured as succinate dehydrogenase activity) within roots, and extraradical mycelium growth. The influence of flooding on the establishment of colonization and on intra- and extraradical AM fungal growth was dependent on the water regime. Continuous flooding reduced colonization and AM fungal growth, whereas tidal flooding did not affect these parameters unless combined with intermediate salinity level (50% seawater) at the end of the experiment. The water regime did not influence AM active colonization. The ratio of root to soil AM fungal growth increased as the water level increased. The results of this study demonstrate that the establishment and activity of AM colonization in A. tripolium is more influenced by salinity than by flooding, and suggests that the functionality of salt marsh AM fungi is not affected by flooding.     

Effect of salinity × calcium interaction on cation balance in melon plants grown under two regimes of orthophosphate

Melon (Cucumis melo L.) plants were grown hydroponically in a greenhouse to investigate the interaction of phosphorus (P) and calcium (Ca) under saline conditions on vegetative biomass and cation balance. Three levels of Ca (0.4, 2, and 8 mM) were combined factorially with two levels of phosphate (0.1 and 1 mM) under two regimes of NaCl salinity (10 and 80 mM). An increase of phosphate and salinity level decreased shoot and root growth. A strong antagonism between Ca and magnesium (Mg) was observed regardless of the salinity level. Calcium effect on growth depended on the salinity level. At low salinity, an increase of Ca reduced sodium (Na) concentration in all plant fractions. At high salinity, this effect was only significant in young and medium leaves. At low salinity and low Ca the reduction of growth could be due to Na toxicity and an unbalanced Ca/Mg ratio. In addition to that, at high salinity, the restoration of growth by increasing Ca concentration in the root medium could be due to an effect on water relation and by increasing potassium K/Na selectivity.