配施木霉微生物肥对连作黄瓜的影响

研究减量化肥与哈茨木霉SQR-T037微生物肥配施对盆栽黄瓜产量、品质及土壤有效养分和可培养微生物数量的影响。试验以当地农民惯用化肥施用量的100%作为对照处理(CF),75%的农民惯用化肥量配施普通有机肥(OF)或木霉SQR-T037微生物肥(BF)作处理进行连续盆栽试验。结果表明,75%的农民惯用化肥量配施木霉微生物肥BF与100%的化肥处理CF产量相等且后期有所增产,相对配施普通有机肥处理OF则产量显著提高,同时黄瓜果实中硝酸盐含量降低45%以上,维生素C含量明显增加。此外,BF处理能有效改善土壤养分供应状况,有效磷和速效钾含量明显高于对照CF和OF处理,并显著提高黄瓜根际土壤细菌、有益菌种木霉的数量,维持放线菌数量稳定,且在施用第三季后显著减少真菌数量。因此,减少25%的化肥并配施一定量的木霉微生物肥(50g株~(-1)),不仅能保证黄瓜稳产,还能显著改善黄瓜果实品质,促进土壤中养分的高效利用,节约施肥成本,促进农业可持续发展。     

适用热区芒果园的木霉生物有机肥研制及其应用

研究从热区土壤中筛选得到的促生木霉菌株及其研制的生物有机肥对芒果产量及品质的影响。通过稀释涂布法筛选出木霉菌株,观测不同温度下生长情况进行初筛,室内盆栽试验复筛得到具有促生效果的木霉菌株;田间条件下,研究施用木霉生物有机肥对芒果产量及品质的影响;最后,结合菌株ITS及tef1序列分析鉴定其分类信息。结果表明:从海南芒果园土壤中筛选出的适温范围较宽的木霉菌株中,菌株MD30在35℃及40℃下生长速度最快。室内条件下菌株MD30试制的生物有机肥对黄瓜苗期的促生作用优于其他木霉菌株,其地上部鲜重和干重较不施肥对照(CK)于第1季分别增加了29%及64%,于第2季分别增加了116%和53%。室内促生效应最为显著的木霉菌株MD30的ITS和tef1序列分析表明该菌株为长枝木霉菌(Trichoderma longibrachiatum)。田间条件下,施用MD30木霉生物有机肥(MD30)当季产量显著高于不施肥对照(CK)、化肥处理(CF)、有机肥处理(OF)和NJAU4742木霉生物有机肥(4742),分别增产13%、7%、6%和3%;同时MD30处理相对于其他处理显著提高了芒果单果重、商品大果重、可溶性固形物和还原糖的含量,其中还原糖含量比4742处理分别增加了25%、22%、7%和6%。因此,长枝木霉MD30研制的生物有机肥提高了芒果果实的产量和品质,对热区植物的生长具有显著的促生效应。     

不同施肥模式对稻田土壤速效养分含量及水稻产量的影响

为了综合评价中国南方稻田不同施肥模式对土壤速效养分及水稻产量的影响,并找到最佳施肥模式,本试验在浏阳市北盛镇、荷花镇和达浒镇3个不同基础地力水稻田块从2013年起进行田间定位试验,比较不施肥、常规施肥、60%化肥+40%有机肥(秸秆+紫云英)和单纯施用化肥处理的水稻产量和土壤速效养分含量变化。3年定位试验表明:不同施肥模式相比无肥处理均能显著提高水稻生物产量,以60%化肥+40%有机肥处理最为显著,且生物产量表现出逐年递增的趋势。通过提高水稻有效穗数和穗粒数使水稻产量显著高于其他处理,60%化肥+40%有机肥处理相比不施肥、纯化肥、常规施肥处理分别增产38.3%~62.4%、1.7%~9.6%、8.4%~12.0%。土壤中速效养分含量表现出60%化肥+40%有机肥处理显著高于其他处理的规律,且速效养分含量逐年递增,而纯化肥处理速效养分逐年递减。从当季作物产量而言,低肥区应加大化肥在有机无机配施中的比例,但从长远培肥地力方面,应适当加大有机肥在配施中所占比例,对于中高肥区则可逐步增加有机肥施用比例。不施肥会降低土壤肥力,而施肥具有明显培肥地力的效果,60%化肥+40%有机肥的施肥模式培肥地力效果最为显著,有利于增加水稻有效穗数和穗粒数,产量显著高于其他处理。     

南方丘陵地区生物黑炭和有机肥配施化肥的应用研究

研究生物黑炭和有机肥配施化肥对旱地作物种植和养分损失的影响,旨在进一步探索高温多雨的南方丘陵地区旱地作物合理施肥和高产高效种植以及资源优化利用的有效途径。采用田间小区试验,设置了5个处理:不施肥(CK)、单施化肥(CF)、化肥+生物黑炭(CF+B)、有机无机肥配施(OF+CF)和有机无机肥配施且添加生物黑炭(OF+CF+B),探讨了生物黑炭和有机肥施用对春玉米产量、地表氮磷径流损失、作物氮磷肥料利用率的影响。结果表明:生物黑炭或有机肥的施用可显著增产8.2%~11.1%,但有机肥和生物黑炭结合施用增产效果最佳,增产率可高达13.7%。相比CF处理,CF+B处理可显著降低15.9%的氮素径流损失和24.2%磷素径流损失,显著提高26.3%和11.8%的地上部氮磷累积量;OF+CF处理可显著降低17.5%的氮素径流损失和25.0%磷素径流损失,提高36.5%(P0.05)和8.2%(P0.05)地上部氮磷累积量;OF+CF+B处理可显著降低33.3%的氮素径流损失和35.2%磷素径流损失,显著提高52.1%和29.0%地上部氮磷累积量,且氮磷肥料利用率最高,分别达49.1%和26.4%。OF+CF+B处理施肥方式一方面可促进春玉米旺盛生长,增加地表植被覆盖度和增强土壤的抗蚀性,显著降低了地表的径流体积;另一方面可以全面降低土壤氮磷养分溶解态和颗粒态的径流损失,培肥了地力。因此,从产量经济效益和环境效益方面综合来看,认为添加生物黑炭和有机肥部分替代化肥结合化肥施入土壤是最合理的施肥方式,值得在该区域进行推广和应用。     

化肥减量配施有机肥对红枣产量及品质的影响

用大棚内枣树施肥试验的方法,研究了化肥减量、配施生物有机肥对枣树农艺性状、产量和枣果品质的影响。试验设CF、0.8CF+0.5BF、0.6CF+1.0BF、0.4CF+1.5BF 4个处理;其中,CF为常规氮、磷、钾化肥用量,BF为生物有机肥常规用量。结果表明:与常规化肥用量(CF)相比,化肥减量配施有机肥三个处理(0.8CF+0.5BF、0.6CF+1.0BF和0.4CF+1.5BF)枣果周长、枣吊长度和枣果长轴显著增加,红枣产量分别增加了19.7%、27.3%和17.1%,单枣重分别增加21.1%、20.7%和11.8%,灰分含量分别增加19.9%、44.2%和35.6%,可食率分别增加1.0%、1.6%和1.4%,出干率分别增加10.2%、0.9%和11.8%,蛋白质含量分别增加18.6%、23.5%和16.2%,维生素C含量分别增加8.8%、29.9%和26.4%,还原糖含量分别增加20.2%、28.8%和27.1%,可溶性总糖含量分别增加21.1%、29.8%和26.5%,有机酸含量分别增加22.0%、12.7%和17.9%,黄酮含量分别增加22.8%、25.0%和4.5%。在本文试验条件下,综合考虑红枣农艺性状、产量和品质等因素,化肥用量为常规用量的60%、配施常规用量的生物有机肥处理(0.6CF+1.0BF)效果最好。     

木霉微生物肥与减量化肥配施对番茄产量、品质及土壤肥力的影响

研究利用植物促生菌提高肥料效率以部分替代化肥。采用大田试验结合连续盆栽试验的方法,以100%化肥(CF)为对照,设置如下处理:75%化肥配施普通有机肥(OF)或木霉微生物肥(BF)或木霉孢子悬液(SS)。结果表明,75%化肥配施以一定量(每株50 g)木霉微生物肥可维持田间番茄稳产,与100%化肥处理产量相当;而与普通有机肥或木霉孢子悬液灌根配施则会显著降低番茄产量,连续栽种4季后,产量下降35%以上。此外,BF处理可显著提高番茄果实的品质,与CF相比,总可溶性糖和维生素C含量分别提高35%~54%和2%~23%,而硝酸盐积累量下降32%~46%。究其原因,BF处理中木霉功能菌的有效定殖促进了番茄根际细菌、真菌、放线菌的增殖,土壤养分的有效性显著提高,表现为根际微生物数量与多项土壤肥力指标呈显著相关关系。综上,木霉微生物肥与减量化肥配施,可有效保证番茄稳产,提高番茄品质,长期施用还可提高土壤微生物数量、改善土壤肥力。     

不同施肥处理对梁平柚产量、品质和土壤肥力的影响

通过连续3 a (2014—2017年)的田间试验,以10 a生梁平柚为研究对象,研究不施肥(CK)、单施化肥(CF)、50%化肥+50%有机肥(CF+OF)和单施有机肥(OF)下梁平柚产量、品质和土壤肥力的影响。结果表明,在不同施肥处理中,CF+OF、OF和CF的单果重均无显著性差异(P0.05),但CF+OF的柚子单株果实数最高,柚子产量分别高出OF、CF和CK 8.2%、31.2%和11.82%;CF+OF处理中,柚子果实中的果汁含量、总糖、游离氨基酸和维生素C比CK分别提高20.40%、18.95%、64.34%和27.06%,而柚子果皮厚度、种子数和总酸度显著降低,品质改善;施肥显著提高土壤微生物生物量碳氮,在不同施肥处理中,微生物生物量碳氮比介于7.39～13.89,且差异显著(P0.05)。CF+OF处理中,柚子成熟期土壤可培养细菌、真菌、放线菌数量显著高于或相似于单施化肥,说明化肥和有机肥配施能促进微生物生长繁殖,协调土壤养分供应,改善柚子营养。虽然不同施肥处理对土壤pH无显著影响(P0.05),但是与CK相比,OF和CF+OF处理有机质和速效钾含量增加,CF处理无显著差异(P0.05);CF、OF和CF+OF处理有效磷含量分别比CK增加6.53%、22.74%和34.72%,且差异显著(P0.05);CF+OF碱解氮含量最高,CF和OF次之,CK最低。此外,有机无机配施还可提高土壤蔗糖酶、脲酶、磷酸酶和过氧化氢酶活性,有益于土壤有机质循环、氮磷养分转化、活性氧消除。总之,在不同施肥处理中,有机无机配施显著提高柚子产量,品质得到明显改善,且土壤养分供应协调,土壤微生物数量增加,土壤酶活性增强,有益于土壤养分转化和保持健康。因此,在梁平柚施肥中,提倡有机无机配施很有必要。     

减施化肥配施有机肥对荔枝生长、产量品质及肥料利用率的影响

针对我国荔枝园化肥施用量过高而存在的土壤质量下降、酸碱失衡和产量下降等问题，综合考虑荔枝施肥养分投入与带走量，研究减施化肥配施有机肥对荔枝生长、产量品质及肥料利用率的影响，旨在为荔枝提质增效提供施肥指导。以妃子笑荔枝为研究对象，设置单施化肥（CF）、减施化肥30%分别配施普通商品有机肥5kg/株（OF5）和10kg/株（OF10）、减施化肥30%配施生物有机肥5 kg/株（BIO5）和10kg/株（BIO10）5个处理，比较不同施肥处理对荔枝生长、养分供应、产量品质、肥料利用率及经济效益的影响。结果表明：（1）化肥减施30%的情况下，配施有机肥未明显减缓荔枝梢期生长。与CF相比，OF5显著促进新梢生长，BIO5显著提高梢期叶片叶绿素含量（SPAD值）；有机肥处理的百叶重及梢粗较化肥处理显著降低。（2）总体来看，在梢期与果实成熟期，各处理间叶片养分含量无显著差异，在二蓬梢期及末次梢期，OF10与BIO5叶片氮含量显著高于CF处理；各处理叶片氮含量均处于适宜范围，各养分含量与变化趋势均符合荔枝生长规律。（3）与CF相比，BIO5、OF10、BIO10处理均显著提高荔枝单株产量，其增幅分别为44.77%、35.81%、18.23%；有机肥处理均有提高荔枝单果重、纵径与横径的趋势；有机肥处理下荔枝果实内在品质高于CF处理，可溶性固形物含量平均增加1.76%-3.22%，可溶性糖含量平均增加11.96%-21.84%，可滴定酸含量平均降低15.38%-35.35%；产量品质综合评价BIO5>BIO10>CF>OF10>OF5。（4）各有机肥处理氮素偏生产力均显著高于化肥处理，BIO5与OF10氮、磷、钾肥偏生产力与农学利用率均显著高于其它处理。OF10、BIO5、BIO10均能显著提高荔枝收益。综合考虑荔枝生长、果实产量及品质、肥料利用效率以及经济效益，该园区在减少30%化肥养分投入下株施5kg生物有机肥处理表现最佳，其次是株施10kg普通商品有机肥。     

化肥减施条件下木霉生物有机肥对茄子生长和品质的影响

以茄子为供试材料,设置4个处理：不施用任何肥料(CK)、常规施肥(T1)、较常规施肥减施30% 化肥(T2)和较常规施肥减施30% 化肥+木霉生物有机肥(T3),研究了木霉生物有机肥对茄子生长、产量和品质的影响。结果表明：T3处理的株高和茎粗高于T2处理,其中株高差异达到显著水平;产量方面,T1≈T3>T2>CK,T1、T2和T3处理的产量较CK处理分别增加23.90%、14.27%、20.19%,T3处理的产量较T2处理增加5.18%;T3处理的可溶性蛋白含量显著高于其他各个处理,且与T2处理相比,VC含量显著提高;经济效益方面,与T2处理相比,T3处理每公顷收益增加8 769.60元。主成分分析结果显示,不同处理下茄子的综合生长及品质排序为：T3>T1>T2>CK,木霉生物有机肥替代30% 化肥处理综合评价最高。聚类分析将4个处理分成3类,T1处理和T3处理归为一类,T1处理生长指标好,有最高的株高、茎粗和产量,T3处理品质指标优异,可溶性糖、可溶性蛋白和VC含量最高,两者综合评价得分相近。综上,木霉生物有机肥替代30% 化肥不仅能够有效提高茄子的株高、茎粗,而且还能显著提高茄子的可溶性蛋白和VC含量,有效改善茄子的品质,同时对于增加茄子产量和经济效益也效果明显。     

不同生物有机肥用量对韭菜产量、品质及养分利用的影响

针对蔬菜生产中施用化肥养分单一、供肥不平衡等问题,研究化肥配施不同量生物有机肥对韭菜产量、品质及养分利用的影响,为韭菜生产合理配施生物有机肥提供理论及技术依据。试验采用随机区组设计,设不施肥(CK)、常规施肥(T1)、2 400 kg/hm2生物有机肥+常规施肥(T2)、3 600 kg/hm2生物有机肥+常规施肥(T3)、4 800 kg/hm2生物有机肥+常规施肥(T4)共5个处理。结果表明,与单施化肥相比,配施生物有机肥可显著提高韭菜产量,同时提高了氮、磷、钾肥利用率及其吸收量。与配施2 400 kg/hm2生物有机肥处理相比,配施3 600、4 800 kg/hm2生物有机肥处理的韭菜干物质积累量和产量均显著提高,但两者之间产量无显著差异。与常规施肥相比,配施2 400、3 600、4 800 kg/hm2生物有机肥处理的韭菜产量和经济收益均显著提高,分别提高13.2%、19.2%、19.9%和10.2%、13.1%、10.1%;配施3 600、4 800 kg/hm2生物有机肥处理均显著提高了韭菜干物质积累量。配施3 600、4 800 kg/hm2生物有机肥处理较常规施肥均能够显著提高韭菜叶片可溶性糖和维生素C含量,分别提高25.0%、28.0%和7.5%、22.0%,硝酸盐含量分别降低19.4%和25.9%,对可溶性蛋白含量均无显著影响。配施3 600、4 800 kg/hm2生物有机肥处理的可溶性糖、维生素C含量均显著高于2 400 kg/hm2生物有机肥处理。各生物有机肥处理氮、磷肥利用率随着生物有机肥用量的增加而提高,钾肥利用率以2 400 kg/hm2生物有机肥处理最高。在保证韭菜高产的同时,配施3 600 kg/hm2生物有机肥能够获得最大经济效益,显著改善韭菜的营养品质,提高韭菜干物质积累量及氮、磷、钾肥的利用率。     

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,     

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.     

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.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

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,     

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,     

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.