稻-稻-油菜轮作对土壤微生物活性和多样性的影响

水稻(Oryza sativa L.)和油菜(Brassica campestris L.)轮作是中国南方地区常见的耕作制度,其优点在于能够提高农业土地利用率和增强土壤生产力,且能改变土壤生态环境。轮作栽培土壤生态环境的改变对作物生长具有益的作用,而土壤中微生物的变化是土壤生态环境改变的重要因素。因此,研究土壤微生物活性和多样性可为水稻和油菜轮作栽培对土壤质地的影响能够提供理论依据,对维持良好的土壤环境生态系统和农田可持续耕作具有重要的现实意义。以浏阳(短期试验:3 a)和安仁(长期试验:30 a)两地的稻-稻-油菜轮作土壤为研究对象,选取稻-稻连作土壤作为对照比较,分别于2015年7月、10月和2016年4月取样测定稻-稻-油菜轮作和稻-稻连作土壤微生物量碳、氮含量。结果表明:就所测得的浏阳土壤微生物量碳含量而言,稻-稻-油菜轮作比稻-稻连作分别高出16.99%、15.26%、32.33%,安仁土壤则分别高出26.38%、20.18%、35.74%;就所测得的浏阳土壤微生物量氮含量而言,稻-稻-油菜轮作比稻-稻连作分别高出34.63%、17.80%、33.81%,安仁土壤则分别高出14.29%、15.31%、14.58%。采用Biolog ECO技术分析土壤微生物多样性,结果表明浏阳和安仁两地稻-稻-油菜轮作和稻-稻连作土壤平均吸光值(AWCD)变化趋势相同,稻-稻-油菜轮作土壤AWCD值大于稻-稻连作,表明稻-稻-油菜轮作提高了土壤微生物对碳源的利用能力。研究结果表明稻-稻-油菜轮作显著提高了土壤微生物丰富度指数,而对均匀度和优势度指数影响不显著。通过主成分分析可知,3个不同时期土壤微生物对碳源的利用以糖类、羧酸类、氨基酸类为主。     

格尔木枸杞地农药残留水平与膳食暴露风险评估

围绕格尔木地区枸杞果农药残留问题,开展从枸杞植株-蜂蜜-土壤-地下水系统迁移环境中农药残留水平及枸杞果膳食暴露风险评估研究。采集地下水、枸杞果实、枸杞茎叶、枸杞蜂蜜以及土壤样品76个,对11种常用农药进行检测,在各种农药残留水平分析的基础上,分别利用急性参考剂量和每日允许摄入量进行急性和慢性膳食暴露风险评估。结果表明,76份样品共检出吡虫啉、阿维菌素、草甘膦和多菌灵4种农药,农药种类残留最多的是枸杞叶和土壤样。从平均残留量和最高残留量来看,吡虫啉在枸杞果实、枸杞叶和土壤中残留量相对较高,最高残留量达88μg·kg~(-1),而在地下水和蜂蜜样中相对较低;其余农药的残留主要集中在土壤和枸杞叶中,阿维菌素和草甘膦在土壤中最高分别达45.5μg·kg~(-1)和1 270μg·kg~(-1),多菌灵在枸杞叶中达到8 400μg·kg~(-1)。4种农药在系统迁移过程中的差异性:草甘膦在土壤中降解性能好,主要残留于土壤中,呈现地表累积特征;多菌灵不溶于水,不易迁移,多残留在枸杞的植株中;吡虫啉具有渗透性强,附着力好、耐冲刷等特点,在土壤、地下水、果实及植物等环境中表现出较明显的稳定性;阿维菌素在酸性和碱性条件下降解不稳定,同时受夏季雨水的冲刷作用,在土壤-地下水迁移过程中表现出不稳定的特征。急性膳食暴露风险和慢性膳食暴露风险均小于100%,暴露风险处于可接受水平。     

番茄连作与轮作土壤生物学特性及细菌群落结构的比较

随着全国番茄(Lycopersicon esculentum)的规模化生产以及形成相对固定的生产区域,番茄连作障碍现象逐年严重。文章针对番茄连作、轮作土壤的生物学特性及细菌群落结构展开了分析,旨在揭示连作与轮作土壤中生物学特性及细菌群落结构的变化规律,为保障番茄产业的可持续发展提供技术支撑。试验分别设置番茄-番茄、番茄-茄子(Solanium melongena)、番茄-辣椒(Capsicum annuum)连作和番茄-黄瓜(Cucumis sativus L.)、番茄-白菜(Brassica campestris L.)、番茄-菜豆(Phaseolus vulgaris)轮作共6个处理。采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)以及稀释平板法等现代和传统分析技术,比较分析了连作和轮作不同蔬菜作物对土壤生物学性状和细菌群落结构的影响。结果表明:番茄连作导致土壤可培养细菌、放线菌数量显著降低,真菌数量显著增加,微生物群落由细菌型向真菌型转变;同时连作还导致土壤中指示土壤肥力的微生物生物量碳、氮和涉及碳、氮、磷循环相关酶活性显著降低;此外,番茄连作导致土壤细菌多样性指数(H)、均匀度指数(EH)和丰富度指数(S)下降,番茄连作土壤中主要以不可培养细菌(Uncultured bacterium)为优势种属。相比之下,番茄轮作不仅能显著增加微生物数量,提高土壤微生物生物量碳、氮和酶活性,而且轮作土壤中除了维持较高的细菌多样性之外,还出现假单胞杆菌属(Pseudomonas sp.)等促生细菌种属。表明番茄轮作有利于提高土壤肥力和保持土壤健康。其中,番茄轮作黄瓜、白菜和菜豆3种不同科属蔬菜作物中,以轮作菜豆更有利于提高土壤肥力和保持土壤健康。     

稻—稻—油菜轮作土壤细菌群落的特征

为了解南方地区稻—稻—油菜轮作后土壤中细菌群落的变化特征,以长达30年的水稻—水稻—油菜轮作和水稻—水稻连作定点栽培试验土壤为研究对象,采用克隆文库和基因序列分析法,通过细菌16S r DNA基因通用引物对土壤提取DNA进行PCR扩增,然后将扩增片段构建克隆文库对克隆子进行测序分析.结果显示,2015年7月、10月和2016年4月3次取样中轮作土壤细菌的香农-维纳指数和辛普森指数均高于连作土壤,轮作土壤细菌多样性高于连作.克隆子序列OTU与Gen Bank比对结果显示,轮作土壤中常见的变形菌(Proteobacteria)占细菌种类的55%,连作土壤为45%;轮作土壤芽单胞菌(Gemmatimonadetes)占细菌种类的13%,连作土壤为10%;轮作土壤中的酸杆菌(Acidobacteria)、厚壁菌(Firmicutes)和浮霉菌(Planctomycetes)所占细菌比例数小于连作土壤;变形菌和芽单胞菌构成了轮作土壤中的优势菌群,土壤优势菌群的变化对细菌群落结构特征产生影响.测序结果显示稻—稻—油菜轮作土壤优势菌群中α-变形菌、β-变形菌和γ-变形菌高于稻—稻连作;稻—稻—油菜轮作中发现与绿弯菌(Chloroflexi)序列相似菌类,而稻—稻连作土壤中未发现.本研究表明微生物群落结构组成与土壤耕作方式相关,稻—稻—油菜轮作增加了细菌群落丰度.     

太湖流域西北部地表水中农药的污染特征及生态风险评价

为研究太湖流域西北部地表水中农药的污染特征、时空分布及生态风险,分别于2019年3月(枯水期)和8月(丰水期)对目标区域的湖泊和重要河流中的农药进行监测分析。采用固相萃取结合高效液相色谱串联质谱法对120个地表水样品中的农药进行分析测定,共检测到7种杀虫剂和5种杀菌剂。整体上,枯水期农药污染较丰水期严重,农药总浓度的平均值分别为191.87 ng·L-1和171.07 ng·L-1。残留最高、分布最广的农药是吡虫啉(浓度范围ND～197.97 ng·L-1,检出率98%)和多菌灵(浓度范围ND～114.44 ng·L-1,检出率97%)。靠近农业区的漕桥河(S5和S6)和锡溧漕河(S36)是重污染区,漕桥河的S6点位是污染最严重的点位。采用风险商指数对农药进行生态风险评估,丰水期地表水中的农药对水生生物的威胁大于枯水期。有机磷类杀虫剂和苯并咪唑类杀菌剂对水生生物具有高风险,需要引起重视。     

设施土壤pH值与有机质演变特征研究

设施土壤的pH、有机质与土壤环境质量及设施栽培作物生产水平密切相关。文章对云南不同区域、不同大棚种植年限、不同轮作制度的设施土壤pH与有机质的演变特征进行研究,结果表明:大棚种植年限长的地区,土壤pH、有机质变化明显;随着大棚种植年限的增长,土壤pH呈下降趋势,有机质含量则呈上升趋势;随着土壤层次的加深,大棚土壤pH逐渐升高,而有机质则逐渐降低;不同轮作方式,花-菜轮作比菜-菜轮作有利于增加有机肥对设施土壤pH的缓冲性。     

香樟根际土壤化感作用的初步研究

化感作用是农林复合生态系统中作物相互作用的重要方式,它有十分重要的经济、生态意义.该研究采用常规水浸提方法制备不同浓度的香樟(Cinnamomum camphora (L.) Presl.)根际土壤水浸提液,用生物测定法测定其对萝卜(Raphanus sativus L.)、红苋菜(Amaranthus mangosfanus L.)和荠菜(Capsella bursa-pastoris (L.) Medic.)的种子萌发和幼苗生长的化感作用.结果表明,浸提液浓度不同,其化感效应不同,受体植物不同,化感效应差别也较大,具体表现为,浓度较低时,化感作用较小,对萝卜根生长起促进作用,随着溶液浓度的增大化感抑制作用逐渐增强,大致表现出低促高抑的规律;萝卜受化感作用抑制作用较其他两种蔬菜小.通过研究可得出结论:香樟对蔬菜有较强的化感作用,香樟林地发展林-菜复合种植一定要选择合适的蔬菜种类和科学的管理措施.     

不同作物对土壤中Ni的富集特征及低累积品种筛选

为探究镍(Ni)污染土壤中农作物食用安全性并筛选出低累积作物品种,以青椒(Capsicum annuum L.)、黄瓜(Cucumis sativus L.)、豇豆(Vigna unguiculata L.)、菠菜(Spinacia oleracea L.)、花菜(Brassica oleracea L.)、青菜(Brassica chinensis L.)、水稻(Oryza glaberrima L.)、小麦(Triticum aestivum L.)为试验材料,采用温室盆栽土培试验方法研究了土壤中不同质量分数(126、200、350、500、650、800mg·kg~(-1))Ni作用下不同作物生物量变化及可食部分Ni富集特征,建立不同种类作物与土壤Ni含量相关关系,探讨不同作物对应的土壤Ni安全限量值,筛选Ni低累积作物品种。结果表明:(1)随着土壤中Ni含量增加,作物地上部分生物量表现为先增加后减少,黄瓜、青菜耐受性最强,花菜耐受性最差;(2)不同作物可食部分Ni富集系数表现为:小麦(0.032)花菜(0.026)青菜(0.021)水稻(0.020)豇豆(0.014)菠菜(0.006 5)青椒(0.005 4)黄瓜(0.004 2);(3)作物可食部分Ni含量与土壤中Ni含量都呈极显著正相关(P0.01),相关系数大小表现为:豇豆(0.972)花菜(0.965)青椒(0.948)菠菜(0.938)黄瓜(0.926)小麦(0.728)青菜(0.721)水稻(0.700);(4)不同作物对应的土壤Ni安全限量值大小为:黄瓜(561 mg·kg~(-1))菠菜(513 mg·kg~(-1))青椒(439 mg·kg~(-1))花菜(203 mg·kg~(-1))豇豆(196 mg·kg~(-1))青菜(190 mg·kg~(-1))水稻(147 mg·kg~(-1))小麦(105 mg·kg~(-1))。依据作物对土壤中Ni的耐受性、富集能力及土壤安全限量值,筛选出黄瓜、青椒、菠菜为Ni低累积品种。该研究为通过农艺技术措施调控作物Ni积累提供依据,对上海轻中度Ni污染复垦土地实施作物替代种植,保障作物食用安全具有重要意义。     

不同轮作制度下施肥对冬小麦田间杂草群落及小麦生长的影响

为探讨不同轮作制度下长期施肥对冬小麦Triticum aestivum L.田间杂草及小麦生长的影响,我们在三个长期田间肥效试验定位点,研究3种轮作制度下(冬小麦-大豆Glycine max (L.) Merr.(WS)、冬小麦-夏玉米Zea Mays L.(WM)、冬小麦-中稻Oryza sativa(WR))长期不同施肥模式对冬小麦田间杂草群落及小麦生长的影响.研究表明,在3种轮作制度下,平衡施加N、P、K肥或者NPK肥配施有机肥均可以显著降低冬小麦田杂草密度、地上生物量和田间光照透过率,促进冬小麦生长,并提高冬小麦产量和地上生物量;而且在冬小麦-大豆轮作和冬小麦-中稻轮作的冬小麦田中平衡施加N、P和K肥可以在控制杂草密度的同时保持一个较均一的杂草群落.3种轮作制度下各指标相对值比较发现,3种轮作制度改变施肥对冬小麦田间光照透过率影响程度的顺序与3种轮作制度改变冬小麦田中施肥对杂草密度和地上生物量影响程度的顺序相同;另外,在冬小麦-大豆轮作和冬小麦-中稻轮作制度下杂草密度与冬小麦田间光照透过率之间的相关系数也很高(R≥0.7906),说明施肥对冬小麦田间光照透过率的改变可能是施肥影响冬小麦田间杂草群落的主要途径之一.轮作制度改变冬小麦田中施肥对优势杂草种类数和杂草生物多样性影响的程度差别不大,这可能是因为轮作改变施肥对田间杂草的影响并没有达到引起田间杂草物种消亡的程度.结果表明,在3种轮作制度中施肥对冬小麦田间杂草群落及小麦生长的影响虽有差异,但都显示出施肥在抑制田间杂草发生、维持杂草生物多样性和提高作物产量上的作用.     

7种农药对管氏肿腿蜂的毒性及初级风险评价

为评估农药对寄生类自然天敌昆虫的安全性,选择管氏肿腿蜂(Scleroderma guani Xiao et Wu)作为受试生物,采用管测药膜法测定了3种杀虫剂、2种除草剂、2种杀菌剂对其致死效应,并根据田间推荐剂量计算暴露量,采用风险商值HQ对杀虫剂进行风险评估。结果显示,与空白对照比较,3种杀虫剂均具明显毒性作用,其中丁硫克百威、吡虫啉和呋虫胺对管氏肿腿蜂的24 h半致死量(24 h-LR50)分别为5.11、2.92和0.06 g a.i.·ha-1,农田内风险商值分别为60.23、16.64和3 105。除草剂和杀菌剂在3倍最大田间推荐剂量作用下,24 h管氏肿腿蜂死亡率均小于50%。上述结果表明,在田间推荐用量下,3种杀虫剂对管氏肿腿蜂的初级风险评价为存在高风险,建议进一步开展高级阶段风险评估或者采取合理的风险管理措施来降低风险;除草剂和杀菌剂对管氏肿腿蜂的风险可接受。     

Herbizide in der aquatischen umwelt

The relevance of artificial pond-systems for the ecotoxicological evaluation of pesticides is discussed. It is the primary advantage of such systems that effects and exposure of a chemical can be examined simultaneously. For the herbicide Metolachlor it was demonstrated that the ecotoxicological evaluation of the herbicid in artificial pond-systems leads to reality-nearer ecotoxicological limits in comparison to “single-species-rests”. Up to a concentration of 500 μg/L, the application of the herbicide had no effects on the physico-chemical parameters and biocoenoses examined, even though the test period was extended over 150 days, which can be regarded as chronic exposure for most of the organisms examined. The results presented indicate once again the importance of pond-studies for a realistic evaluation of pesticides.     

Toxicity,monitoring and biodegradation of the fungicide carbendazim

The increasing use of toxic pesticides is a major environmental concern. Carbendazim is a systemic fungicide having wide applications for controlling fungal diseases in agriculture, forestry and veterinary medicines. Carbendazim is a major pollutant detectable in food, soil and water. Carbendazim extensive and repeated use induces acute and delayed toxic effects on humans, invertebrates, aquatic life forms and soil microorganisms. Here, we review the pollution, non-target toxicity and microbial degradation of carbendazim for crop and veterinary purposes. We found that carbendazim causes embryotoxicity, apoptosis, teratogenicity, infertility, hepatocellular dysfunction, endocrine-disrupting effects, disruption of haematological functions, mitotic spindle abnormalities, mutagenic and aneugenic effect. We also found that carbendazim disrupted the microbial community structure in various ecosystems. The detection of carbendazim in soil and reservoir sites is performed by spectroscopic, chromatographic, voltammetric, nanoparticles, carbon electrodes and mass spectrometry. A review of the degradation of carbendazim shows that carbendazim undergoes partial to complete biodegradation in the soil and water by Azospirillum, Aeromonas, Alternaria, Bacillus, Brevibacillus, Nocardioides, Pseudomonas, Ralstonia, Rhodococcus, Sphingomonas, Streptomyces and Trichoderma.     

光合细菌PSB07-15对辣椒及土壤中甲氰菊酯残留的生物修复

利用光合细菌菌株PSB07-15对辣椒促生作用及对植株与土壤中甲氰菊酯残留的生物修复进行了研究,为光合细菌生物修复菊酯类农药残留的实际应用提供科学依据。结果表明：菌株PSB07-15菌液用ddH2O稀释100倍液、200倍液浸种处理后能够显著提高辣椒种子发芽率;田间小区试验结果表明,菌株PSB07-15施用1 875、3 750、7 500 mL.hm-2,辣椒鲜质量分别增加15.12%、21.68%、14.79%;菌株PSB07-15能够有效降解辣椒和土壤中甲氰菊酯残留（辣椒中大于47.20%,土壤中大于50.73%）。     

10种常用农药对赤子爱胜蚓(Eisenia foetida)的急性毒性效应

为了评价农药对土壤无脊椎动物种群的生态风险,采用OECD标准滤纸法和人工土壤法测定了10种常用农药对蚯蚓(Eisenia foetida)的急性毒性效应。采用滤纸法,48h测定结果表明,4种氨基甲酸酯类(异丙威、甲萘威、速灭威和丁硫克百威)和2种有机磷类(毒死蜱和哒嗪硫磷)农药对蚯蚓的急性毒性(其LC50值为3.50(2.77～4.44)～72.42(59.58～88.05)μg·cm-2)明显高于3种昆虫生长调节剂(噻嗪酮、虫酰肼和呋喃虫酰肼)和吡蚜酮对蚯蚓的急性毒性(其LC50值>629.1μg·cm-2)。采用人工土壤法,14d测定结果表明,上述4种氨基甲酸酯类农药对蚯蚓的急性毒性(其LC50值为59.61(55.13～64.44)～134.1(127.0～141.5)mg·kg-1)明显高于上述2种有机磷类农药和其他农药对蚯蚓的急性毒性(其LC50值为193.0(180.1～206.8)～386.4(359.7～414.2)mg·kg-1)。上述结果表明,不同类型的农药对蚯蚓的毒性存在较大差异,且同一类型的不同农药品种对蚯蚓的毒性也存在较大差异。总体来看,氨基甲酸酯类农药比其他类型的农药对蚯蚓具有更高的毒性。根据《化学农药环境安全评价试验准则》,本研究采用人工土壤法测定的所有农药对蚯蚓均为低毒级。     

辣椒倍半萜环化酶基因在几种非生物诱发因子作用下的表达

报道了在CuCl2,HgCl2及NaCl、紫外线等几种诱发因子作用下辣椒倍半萜环化酶活性表达，并利用从辣椒中克隆出来的2个倍半萜环化酶等位基因cDNA的特异性片段，研究这两个等位基因在上述诱发因子作用下的表达情况，结果表明：在CuCl2,HgCl2,NaCl2、紫外线诱发作用下，离体辣椒叶片均能表现一定的倍半萜环化酶活性，而CK中几乎检测不出倍半萜环化酶活性，Northern Blot分析表明，辣椒倍半萜环化酶基因在逆境下被诱转导，两个cDNA在不同的诱发因子在相同的逆境胁迫下的表达有一定的特异性，推测该基因家族的不同成员在辣椒适应不同逆境的防御反应中有一定的意义，图5参6。     

A new ecotoxicological test method for genetically modified plants and other stressors in soil with the black fungus gnat <Emphasis Type="Italic">Bradysia impatiens</Emphasis> (Diptera): current status of test development and dietary effects of azadirachtin on larval development and emergence rate

Background

Few suitable and standardized test methods are currently available to test the effects of genetically modified plants (GMP) on non-target organisms. To fill this gap and improve ecotoxicological testing for GMP, we developed a new soil ecotoxicological test method using sciarid larvae as test organisms.

Results

Bradysia impatiens was identified as a candidate species. Species of the genus Bradysia occur in high numbers in European agroecosystems and B. impatiens can be reared in the laboratory in continuous culture. A functional basic test design was successfully developed. Newly hatched larvae were used as the initial life stage to cover most of the life cycle of the species during the test. Azadirachtin was identified as a suitable reference substance. In several tests, the effects of this substance on development time and emergence rate varied for different temperatures and test substrates. The toxicity was higher at 25 °C compared to 20 °C and in tropical artificial soil compared to coconut fiber substrate.

Conclusions and outlook

Results suggest that the developed test system is suitable to enter a full standardization process, e.g., via the Organisation for Economic Co-operation and Development. Such a standardization would not only assist the risk assessment of GMP, but could include other stressors such as systemic pesticides or veterinary pharmaceuticals reaching the soil, e.g., via spreading manure. The use of sciarid flies as test organisms supports recommendations of EFSA, which stressed the ecological role of flies and encouraged including Diptera into test batteries.

     

Luzernemehl-induzierte Aktivitätserhöhung (LIA) in ökotoxikologisch-mikrobiologischen Tests

In previous trials, lucerne-meal induced increase in microbial activities (=LIA) was used as a new ecotoxicological indicator of pesticide effects on soil microorganisms. In the following, this technique has been applied to measure and compare the effects of the two dinitrophenol herbicides ‘Flüssig Herbogil’ (active ingredient dinoterb) and ‘Aretit flüssig’ (active ingredient dinoseb acetate) used as reference compounds. A loamy sand soil known for its sensitive microflora was treated with the herbicides and incubated up to 90 days under laboratory conditions. In order to ensure the comparison of the specific effects, equal amounts of the active ingredients of the two formulated herbicides, based on the field rate of ‘Flüssig Herbogil’, were applied. In a parallel trial, the soil was additionally amended with lucerne meal to enable the determination of its specific stimulatory effect on microbial activity. The two biomass-related microbial activities dehydrogenase (=DHA) and glucose-induced short-term respiration (=KZA) were measured, as well as the nitrogen mineralization (=N_min). Depending on the dosage, the activities of LIA-DHA, LIA-KZA and LIA-N_min as increased by lucerne meal, were affected by the herbicides. Normally, the biomass-related activities were inhibited with exception of LIA-DHA at the single dosage. However, the nitrogen mineralization was enhanced. In most cases, the effects caused by ‘Flüssig Herbogil’ (dinoterb) were more pronounced than those of ‘Aretit flüssig’ (dinoseb agetate) when the same amount of the active ingredients had been applied. The LIA of the tested microbial activities proved to be a sensitive indicator for pesticide effects on soil microorganisms. It enabled the differentiation of the ecotoxic effects of chemically similar pesticides. Using this indicator will support results from separate trials run with or without lucerne meal, because marked losses of microbial biomass will become more pronounced. In addition, this improves the interpretation of ecotoxicological effects of pesticides in soil.     

Costs and benefits of capsaicin-mediated control of gut retention in dispersers of wild chilies

A fundamental way in which animal-dispersed plants can influence the viability and distribution of dispersed seeds is through control of retention time in the guts of dispersers. Using two species of wild chilies and their dispersers, we examined how chemical and physical properties of fruits and seeds mediate this interaction. Capsicum chacoense is polymorphic for pungency, occurs in Bolivia, and is dispersed mostly by elaenias. Capsicum annuum is not polymorphic, occurs in Arizona (USA), and is dispersed mostly by thrashers. We first tested whether capsaicin, the substance responsible for the pungency of chilies, affects gut retention time of seeds in primary dispersers. Capsaicin slowed gut passage of seeds but did so in a manner that differed greatly between bird species because the constipative effects of capsaicin occurred only after an 80-minute time lag. Elaenias in Bolivia held only 6% of C. chacoense seeds for > 80 minutes, whereas thrashers in Arizona held 78% of C. annuum seeds for > 80 minutes. Next we examined the effects of retention time on seed viability and germination. Increased retention resulted in a greater proportion of seeds germinating in C. annuum, had no effects on non-pungent C. chacoense, and had negative effects on pungent C. chacoense. These divergent effects are explained by differences in seed coat morphology: seed coats of pungent C. chacoense are 10-12% thinner than those of the other two types of seeds. Thus, longer retention times damaged seeds with the thinnest seed coats. In C. annuum, seed viability remained high regardless of retention time, but germination increased with retention, suggesting a role for scarification. Thus, in C. annuum, fruit chemistry appears well matched with seed morphology and disperser physiology: capsaicin extends gut retention for most seeds, resulting in greater seed scarification and higher germination rates. Increased retention of pungent C. chacoense seeds is detrimental, but because the primary consumers have short retention times, capsaicin slows only a small proportion of seeds, minimizing negative effects. These results illustrate the importance of context in studies of fruit secondary metabolites. The same chemical can have different impacts on plant fitness depending on its morphological, physiological, and ecological context.     

生态肥料 NutriSmartTM在甜椒生产中应用的生态效应

过量施用肥料导致产品质量下降,引发水体和土壤的严重污染;减少施用农田化肥或施用对环境影响较小的肥料将有利于减少农田N、P损失。因此,世界各国尝试研究和开发既能提高作物产量和质量又可降低环境风险的新型肥料。生态肥料Nutrismart在甘蔗、野菜种植上均取得较好的成效,但在蔬菜上的应用研究及其施用后的N、P损失研究鲜见。本研究以甜椒(Capsicum annuum var.grossum)为例,进行温室培养试验,共设8个处理,采用不施肥、纯施常规化肥和混施不同比例的生态肥料NutriSmartTM和常规化肥的技术,比较生态肥料NutriSmartTM和常规化肥混施与单独使用常规化肥对甜椒产量及品质的影响,并进一步通过土柱淋溶试验模拟研究生态肥料对土壤氮磷损失的影响,评价其生态风险。结果表明,生态肥料NutriSmartTM的施用,不仅大幅度降低化肥的用量,还保持了甜椒的产量和质量,且施用量的提高未增加土壤中氮、磷的淋溶,造成水体富营养化的风险降低,在蔬菜中有良好的应用前景。     

土壤生态毒理学研究进展与展望

土壤生态毒理学是污染土壤生态风险评价以及土壤污染控制的理论依据,土壤环境中有毒物质的生态毒理效应及其分子机制的研究是土壤生态毒理研究的核心内容．首先从土壤重金属污染胁迫、有机污染胁迫以及复合污染的联合胁迫三个方面,概述了土壤污染所致的生态毒理效应最新研究进展;在理论剖析种群水平上污染土壤的分子生态毒理效应的基础上,较为系统地介绍了各种与污染土壤生态毒理效应有关的生物标记物,论述了污染土壤生态毒理分子诊断的基本原理、意义并对其今后的研究动态给予了分析;最后,对土壤生态毒理学研究今后的发展进行了展望．