2005—2020年广西左右江革命老区耕地多功能耦合协调度时空分布及影响因素

[目的]分析广西壮族自治区左右江革命老区县级尺度耕地农业生产、社会保障与生态安全功能的空间分布特征,为优化耕地多功能配置,促进区域协调发展提供依据。[方法]通过构建耕地多功能评价体系,运用熵权法、耦合协调度方法测算广西左右江32个县域耕地多功能的协调关系,运用灰色关联度分析法揭露各指标对耕地多功能系统的影响。[结果] 2005—2020年广西左右江耕地农业生产能力和生态安全维持能力持续提高,社会保障功能有所下降;2005—2020年广西左右江各县区耕地多功能综合指数平均值呈现差异,即“边缘高,中间低”的状态;在耦合协调度方面,广西左右江耕地的3个功能尚未达到良性共振阶段,但整体上朝着正向发展;从总体来看,各指标对广西左右江耕地整体功能影响是从2005年的人口数量、耕地资源禀赋和要素投入过渡到2020年的经济发展水平和城市化水平。[结论]未来各县区可根据耕地主导功能的不同因地制宜地利用耕地,以促进耕地多功能子系统间的协调发展。     

城镇化进程中耕地多功能权衡/协同关系演变及其驱动机制

城镇化进程中中国耕地利用功能变化深刻，探究影响耕地多功能协同与权衡的城镇化因素更是平衡地区经济发展与耕地保护的关键。该研究以淮海经济区为例，选取2000-2018年连续年份时间，从耕地生产、社会和生态三个维度构建评价体系分析耕地多功能时空特征，利用Spearman秩相关分析揭示耕地多功能间权衡与协同的时空演化，运用调节效应模型定量剖析权衡与协同演化的城镇化驱动机制。结果表明：1）耕地生产功能整体呈持续增长趋势，社会功能整体呈持续下降趋势，生态功能整体呈波动下降趋势。2）耕地生产与社会功能整体呈弱权衡向弱协同转变，且大部分地市内部的两功能权衡关系有所缓解，协同区域逐渐向东部转移。耕地生产与生态功能整体呈权衡增长趋势，但部分地市内部的两功能关系趋向协同发展，主要分布在鲁南和苏北地区。3）耕地生产与社会功能相互关系主要受城乡收入差距、人口城镇化率以及居民消费能力的影响。耕地生产与生态功能相互关系则受居民消费能力的显著影响。同一驱动因子在不同水平下对耕地多功能之间权衡与协同关系的作用程度不同。为此提出促进淮海经济区耕地多功能协同发展的策略建议。     

中国耕地多功能耦合协调时空演变及其驱动因素

为探究耕地多功能耦合协调演变规律及其驱动因素，该研究依据2000-2018年中国30个省级行政区统计数据，综合评价耕地“生产-生活-生态”三维功能水平并采用核密度估计和可视化制图刻画耕地多功能时空特征，进而采用耦合协调度模型分析耕地多功能耦合协调关系，最终采用地理探测器识别耕地多功能耦合协调演变的驱动因素并解析其驱动机制。研究结果表明：1）耕地生产功能水平、生活功能水平和生态功能水平分别处于[0.030,0.608]、[0.042,0.672]和[0.058, 0.897]范围，生产功能呈现上升-下降-上升波动变化，生活功能水平先上升后下降，生态功能水平则整体小幅提升，各项功能均具有极化特征。耕地生产功能、生活功能和生态功能空间格局分别呈现“东高西低”“北高南低”和“西高东低”分布特征。2）耕地多功能耦合协调水平处于[0.093, 0.554]范围，整体稳步提升但水平仍然较低，多数省份耕地多功能仍为失调状态。耕地多功能耦合协调空间格局逐渐呈现集聚提升的演化特征，东北地区、京津冀地区和长三角地区耕地多功能耦合协调水平较高，西北地区则处于较低水平。3）耕地多功能耦合协调度演变受经营主体条件...     

浙江省耕地多功能时空格局变化、影响因素及空间溢出效应

探讨耕地多功能的时空变化规律、影响因素及其空间上的溢出效应或交互作用，对深化耕地多功能认知、提升耕地资源可持续利用能力具有重要意义。该研究选取浙江省为研究区域，基于耕地利用、气象、土壤、社会经济等数据，综合运用GIS制图、空间自相关分析和基于可拓展随机性环境影响评估（Stochastic Impacts by Regression on Population，Affluence and Technology，STIRPAT）的面板空间计量模型探讨了浙江省2000-2015年耕地多功能的时空变化特征、影响因素及空间溢出效应。结果表明：1）2000-2015年浙江省各区县耕地功能综合水平呈现"先减少，后增长"的变化趋势，耕地物质产出功能、净固碳功能和景观美学功能均呈上升趋势，水源涵养功能保持平稳，劳动力承载功能逐步降低；2）耕地多功能水平的提升对邻近地区有较强的辐射影响作用，本县域耕地多功能水平每增长1%将导致邻近县域耕地多功能水平增长0.224%。农业劳动力、农村居民可支配收入和农业机械水平对耕地多功能具有显著的正向效应，第二产业占比和城镇化水平对耕地多功能具有显著的负向效应；3）第二产业占比、农业现代化水平、农业劳动力投入对耕地多功能有直接效应，城乡居民收入、城镇化水平对耕地多功能水平有溢出效应。研究建议重视区县内部以及区县与邻近地区之间的空间交互作用，加强区域间土地整治、生态保护和农业技术升级等多方面合作。应充分考虑各县域资源禀赋的特殊性以及社会经济发展阶段的异质性，制定针对性的耕地保护和农业扶持适应策略。     

基于选择试验法的北京市城乡居民耕地保护支付意愿研究

[目的]测算北京市城乡居民耕地保护的支付意愿,检验二者的支付意愿差异,并分析差异形成的原因,为制定面向对象差异化的耕地保护政策提供理论借鉴。[方法]采用选择试验法(CE),R统计及部分经济学模型。[结果]农村居民对保护耕地面积、耕地质量和耕地景观生态环境的支付意愿分别为67.24,113.75,51.47元/a,而城镇居民的支付意愿分别为58.07,66.40,150.80元/a。[结论]城镇居民的支付意愿明显高于农村居民,个体支付意愿与其文化程度、家庭年总收入、家庭抚养人口数显著相关;从二者耕地功能需求的角度看,城乡居民对耕地各项功能需求最高的分别为生态功能与生产功能,在需求差异的驱动下样本在选择集中做出符合自己需求偏好的选择。     

2000—2020年华北平原耕地综合价值及其时空变化

[目的] 测算华北平原耕地的综合价值,分析价值差异和变化趋势,为中国耕地保护提供科学依据,促进形成耕地“多位一体”的保护新格局。[方法] 基于耕地的现实功能与人为耕作的影响,将耕地的价值分为正向价值(经济价值、社会价值、生态价值)和负向价值(农药、化肥),利用收益还原法、价值替代法和当量因子法对华北平原2000,2010,2020年耕地的综合价值进行核算。[结果] 2000,2010,2020年华北平原耕地价值分别为5.01×10¹²,8.45×10¹²,6.43×10¹²元;耕地的经济价值比例呈下降趋势,且正向价值在研究时段均大于负向价值。此外,各省间耕地价值分布不均衡,受耕地面积、耕作方式和农产品价格影响较大;其中,山东省耕地价值一直较为突出,河南省变化幅度较大;各省单位面积耕地的负向价值均呈上升趋势。[结论] 2000,2010,2020年,华北平原的正向价值中,经济价值比例呈下降趋势,耕地的社会价值和生态价值的重要性逐渐凸显。各省单位耕地负向价值的区域差异较大,且负向价值均呈上升趋势,河南省最为明显,农膜、化肥等对耕地的负向影响一直没有得到有效治理,且呈逐年加重的趋势。     

基于多功能评价与权衡-协同关系的福建省耕地区划管控

为促进耕地功能协调发展,实现耕地的科学保护与合理利用,该研究构建耕地多功能评价体系,以县域为评价单元,运用综合分析法和Pearson积矩相关系数法,评价2005—2020年福建省耕地多功能水平,分析其时空变化特征和各维度功能间权衡-协同关系。研究结果表明：1）耕地多功能水平在福建大部分地区微幅下降,高值区集聚于耕地生产条件和生态条件优越,且对农民生活和就业保障能力较高的闽东和闽西地区。其中,生产功能呈现上升趋势;生态功能略微下降;社会功能与景观功能均有所提高,前者空间变化由山区向沿海地区减弱,后者相反。2）各维度功能间多以权衡关系为主,仅生产-生态功能和生产-景观功能呈现协同关系的区域占50%以上。呈现权衡关系的栅格数量比例由高到低分别为生态-社会功能、生产-社会功能、社会-景观功能与生态-景观功能,且各对功能组合的权衡-协同关系存在空间异质性。3）根据耕地现状条件,结合各地区农业生产特点,通过叠加耕地单项功能组合与不同功能间权衡-协同关系,将耕地功能区划分为4类区域,包括优势保护区（38.52%）、严格管控区（36.71%）、整治修复区（6.98%）和转型退出区（17.79%）,并提...     

湖北省粮食生产及其影响下的土地资源承载力格局

[目的]为科学评估湖北省土地资源和人口可持续发展现状,对湖北省1949—2012年的粮食生产特征和土地资源承载力进行分析。[方法]通过引入粮食生产相对波动指数、土地资源承载力模型和土地资源承载指数模型进行详细评估。[结果]研究期内湖北省粮食生产呈周期性波动特征,生产过程受自然灾害和政策影响显著,平衡外界影响因素能力薄弱,容易出现起伏;人口增幅小于粮食产量增幅,人均粮食占有量呈4个明显波动周期;2012年湖北省土地资源承载力主要以人口超载、粮食短缺为主要特征。中部平原湖区耕地资源丰富,人粮关系协调,为粮食盈余区域;西部山区和东南部武汉城市圈耕地资源缺乏,人口压力较大,粮食短缺,为人口超载区域。[结论]保护耕地,发展农业科技,提高单产,扩大农业生产规模和稳定粮食生产政策是切实保障湖北省农业稳定发展的重要途径。     

中国第二次土地调查以来省域耕地利用时空变化

[目的]分析和研究全国第二次土地调查(简称"二调")以来各省级空间地域单元的耕地利用现势分布和省域耕地利用的时空特征,以期寻求促进耕地资源可持续利用的针对性政策改进措施。[方法]基于2009—2016年全国和省级年度土地利用现状数据,利用GIS空间分析、数学指数模型等方法进行研究。[结果]①2009—2016年间中国耕地面积总体呈减少趋势,其中旱地减少面积多于水田、水浇地增加面积,耕地总面积共减少4.64×10~5 hm~2,但基于各省域间资源禀赋的异质性和社会经济发展差异,耕地面积分布与利用呈现出明显的差异性。②受不同阶段耕地保护政策的影响,耕地面积在时间和空间不同维度上均或多或少受政策调控,这是形成耕地利用时空变化格局的重要原因。③中国的耕地保护政策需要在耕地利用的时空变化分析基础上进一步加以科学优化,并积极引导区域耕地利用与资源环境协调发展。[结论]现阶段耕地资源利用具有较强的空间、时间异质性和动态变动性特征,而全国省域耕地利用变化过程受到全局性和区域性政策演进与人类活动定向干预的双重作用,亟需在及时跟进和把控耕地变化特征差异的基础上,通过适时合理的政策调控实现对省域耕地资源差异化保护和利用,以保障粮食安全和协调资源匹配,促进区域可持续发展。     

近14年安徽省耕地资源安全的时空特征

[目的]探究近14a安徽省耕地资源安全时空特征,为安徽省社会经济发展和耕地保护提供依据。[方法]从耕地资源数量、质量和生态安全3个方面选取27个评价指标,构建耕地资源综合安全评价体系。[结果](1)安徽省耕地数量和质量安全程度分别呈下降和上升趋势,生态安全等级较为稳定,综合安全呈缓慢上升趋势;(2)耕地资源数量安全总体呈皖东、皖北高于皖南的空间格局;质量安全呈现皖中、皖南高于皖北的特征;生态安全表现为皖中部和皖南较低,其余较高的空间格局;综合安全与数量安全空间分布具有相似性,且在时间上,低安全等级地市呈现"集中—分散"的空间特征,高安全程度地市反之。(3)近14a安徽省耕地资源数量、质量和生态安全的主要障碍因子具有明显的时间变化特征。[结论]安徽省耕地资源安全情况不容乐观,各地区需因地制宜,提高安全保障程度。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.