西北地区马铃薯疮痂病病原菌鉴定及其生物学特性

为明确西北地区马铃薯疮痂病病原菌的种类和生物学特性,分别采用常规组织分离法和土壤混悬液分离法从宁夏、陕西和甘肃3个省区采集的29份疮痂病发病薯块和8份发病地块土壤中进行病原菌分离,并利用形态特征、生理生化特性和16S rDNA序列分析对病原菌进行鉴定。结果表明,从发病薯块和发病土壤中共分离到50株链霉菌Streptomyces spp.,通过回接法验证获得6株马铃薯疮痂病致病菌株。6株致病菌株的培养特性和形态特征差别较大;其中菌株G4-1、G9和SYN13不能以果糖和木糖为单一碳源,菌株SYNT3不能以棉子糖为单一碳源;除菌株NLG4-1外,其余5株菌株均能在络氨酸琼脂培养基上产生黑色素。经16S rDNA序列分析,菌株G4-1、G9与疮痂病链霉菌S. scabiei的相似率分别达99.47%和99.34%,菌株NLG4-1、SYNT3与S. enissocaesilis的相似率分别达97.90%和98.18%,菌株GBH2与加利利链霉菌S. galilaeus的相似率达99.93%,菌株SYN13与S. turgidiscabies的相似率达97.56%,表明西北地区马铃薯疮痂病病原菌至少存在4个种。     

黑龙江省部分地区马铃薯疮痂病菌种类及致病性鉴定

为明确黑龙江省马铃薯疮痂病病原菌的种类及其特征,2012-2013年从黑龙江省克山县、绥化市、哈尔滨市、杜尔伯特蒙古族自治县采集具有疮痂病病斑的马铃薯块茎,从中分离纯化病原菌,根据16SrRNA基因的差异采用分子手段对所分离的菌株进行种类和致病性鉴定,并对txtAB阳性菌株采用萝卜幼苗法或马铃薯致病性试验测定其致病性。共分离出74株菌株,鉴定出致病性菌株26株,其中Streptomyces scabies或S.europaeiscabiei 21株,S.turgidiscabies 3株和S.acidiscabies 2株。所有的致病性菌株中共有4种致病岛基因型,即nec1+/tomA+、nec1-/tomA+、nec1+/tomA-和nec1-/tomA。     

甘肃马铃薯疮痂病病原初步鉴定

对甘肃不同地区马铃薯疮痂病病原进行了分离鉴定.采用盆栽方法进行致病性测定、形态特征、生理生化特性测定和16S rDNA序列分析.结果表明:共有6株菌能使马铃薯块茎出现疮痂症,分别为GP-1、GP-2、GH-1、GH-2、JB-1和JB-2.经鉴定菌株GP-1、JB-2的形态特征、生理生化特性及16S rDNA序列与Streptomyces scabies 87 22菌株均一致;GP-2、JB-1的16S rDNA序列与S.scabies菌株相似性为99％.菌株GH-2和GH-1与S.griseus的16S rDNA序列相似性分别为100％和99％,形态特征一致,但不能以棉籽糖和肌醇为单一碳源,暂定为S griseus.     

甘肃省马铃薯束梗褐腐病病原鉴定及其生物学特性研究

对甘肃省马铃薯(Solanum tuberosum L.)束梗褐腐病病原进行了分离鉴定和生物学特性研究。经形态特征观察与rDNA-ITS序列分析, 将病原菌鉴定为细基束梗霉［Doratomyces stemonitis (Pers. ex Fr.) F.J. Morton & G. Smith］。生物学特性研究结果表明, 病菌菌丝生长最适温度为25～30 ℃, 最适pH为6, 病菌能利用多种碳源, 但以蔗糖最好, 氮源以甘氨酸最适, 光照对菌丝生长没有影响。分生孢子在5～40 ℃范围内均能萌发, 最适25 ℃, 最适pH为7, 分生孢子萌发需液态水, 湿度低于99%几乎不萌发, 马铃薯汁液和葡萄糖液对孢子萌发有较好的促进作用。本研究为马铃薯束梗褐腐病的防治提供了理论依据。     

我国马铃薯疮痂病及其防治研究进展

马铃薯疮痂病(potato common scab)是由放线菌目链霉菌属的链霉菌Streptomyces spp.引起的土传兼种传病害,广泛分布于世界各马铃薯种植区,不仅影响马铃薯的外观品质和销售价格,严重时还会导致马铃薯出苗延迟甚至引起幼苗死亡,造成产量下降,给马铃薯产业带来巨大的经济损失,已经成为全球危害马铃薯生产的第四大病害。2015年我国确立马铃薯主粮化战略,推动了马铃薯产业的发展。近年来,随着种植区域和规模不断扩大,马铃薯疮痂病在我国很多省(自治区)有不同程度的发生,并有逐年扩大和加重的趋势,严重影响商品薯、加工原料薯和种薯的生产,成为制约我国马铃薯生产的主要病害。本文对马铃薯疮痂病症状、发病因素、传播规律、致病机理、分类方法以及我国马铃薯疮痂病发生情况、种类及分布进行归纳,并对马铃薯疮痂病防治措施进行总结,以期为我国马铃薯疮痂病的研究和防治奠定理论基础。     

侧孢短芽胞杆菌JYC 688鉴定及抑菌促生特性研究

马铃薯疮痂病是由多种致病链霉菌侵染引起薯块表面结痂导致薯块外观品质下降的病害,防控困难,生物防治是其主要防治措施之一。筛选具有良好拮抗作用的生防菌,可为马铃薯病害的生物防治提供优良的微生物资源。本研究从健康马铃薯植株根际土壤中分离获得JYC 688菌株,采用平板对峙和纸碟法筛选验证菌株拮抗性,结合形态学观察、生理生化特性测定及分子生物学手段确定其种属地位,并检测其产生水解酶和嗜铁载体的能力。结果表明,菌株JYC 688是侧孢短芽胞杆菌Brevibacillus laterosporus,其菌株培养液能够显著抑制引起马铃薯疮痂病的酸性疮痂链霉菌Streptomyces acidiscabies和肿胀疮痂链霉菌S.turgidiscabies的生长,抑菌圈直径分别为27.86 mm和31.90 mm;其对马铃薯晚疫病菌Phytophthora infestans、早疫病菌Alternaria alternata、黑痣病菌Rhizoctonia solani也具有良好的抑制活性;菌株JYC 688能够分泌β-1,3葡聚糖酶、纤维素酶、蛋白酶、嗜铁素等多种抗菌相关物质,可溶解大豆卵磷脂、碳酸钙、碳酸镁3种难溶性化合物,有利于磷、钙、镁3种元素的释放,是一株具有开发潜力的生防菌。     

糜子丝黑穗病病原菌鉴定及其生物学特性

为明确陕西省糜子丝黑穗病病原菌种类及其生物学特性,采用组织分离法和单孢分离法对其进行分离纯化,通过形态学特征和ITS序列分析对其进行鉴定,采用幼苗浸种法测定其致病性,并于室内对其生物学特性进行研究。结果表明,从发病糜子叶片和病瘿中共分离得到6株形态特征一致的菌株,代表菌株YL11-1菌落呈酵母状,白色,厚垣饱子呈球形或近球形,大小约7～10μm;菌株YL11-1的ITS序列(GenBank登录号为KT721292.1)与稷光孢堆黑粉菌Sporisorium destruens的相似性为100%,接种菌株YL11-1后糜子出现4种典型病症,根据形态学特征、生物学特性和致病性分析结果将该病原菌鉴定为稷光孢堆黑粉菌。该菌株厚垣孢子萌发及菌丝最适生长温度范围均为25～30℃,最适产孢温度为30℃;厚垣孢子萌发和菌丝生长最适pH范围分别为3～7和5～7,最适产孢pH为7;厚垣孢子萌发最适碳源为0.5%葡萄糖和1.0%蔗糖,该菌株对葡萄糖的利用效果最好,对淀粉的利用效果最差;菌丝生长和产孢最适氮源分别为硝酸钾和硫酸铵,该菌株对硝酸铵的利用效果最差。     

红海榄赤斑病病原菌鉴定及其生物学特性研究

 本文对来自红海榄(Rhizophora stylosa)赤斑病同一病斑上获得的2个菌株PⅠ-1和PⅡ-3进行了鉴定和生物学特性研究。结果表明,PⅡ-3菌株的致病力比PⅠ-1的稍强;2个菌株均具有一定的寄主专化性。经形态特征观察与rDNA-ITS序列分析,2个菌株均鉴定为异色拟盘多毛孢(Pestalotiopsis versicolor)。生物学特性测定结果表明,温度、pH值和光照对2个菌株菌丝生长及孢子萌发的影响差异不大,生长温度均为10~32℃(最适25℃),pH值为3.0~10.9(最适4.0);孢子萌发温度均为10~35℃(最适25~28℃),pH值为2.5~8.0(最适3.0);黑暗条件有利于2个菌株菌丝生长和孢子萌发。但2个菌株的产孢特性存在明显差异,其中PⅠ-1产孢的最适温度为28℃而PⅡ-3为20℃;PⅠ-1产孢的最适pH值为5.1而PⅡ-3为9.0;PⅠ-1产孢对光照不敏感,而PⅡ-3在黑暗条件下几乎不产孢。另外,在相似条件下,PⅠ-1产孢量比PⅡ-3大,而PⅡ-3菌丝生长速度比PⅠ-1快,孢子萌发率也比PⅠ-1高。由此可见,2个菌株PⅠ-1和PⅡ-3虽属于同一个种,但某些生物学特性存在一定的差异。     

生物有机肥GSJ-1对马铃薯土壤疮痂病病原菌分布影响及生防效果研究

为了确定生物有机肥 GSJ －1对连作马铃薯土壤疮痂病病原菌分布影响及对马铃薯疮痂病的防治效果,本试验进行了土壤疮痂病病原菌含量测定、马铃薯疮痂病病情田间调查。结果表明,连作土壤疮痂病病原菌在盛花期之前向根际富集,盛花期之后向匍匐茎和薯块富集。施用生物有机肥 GSJ －1显著降低了土壤疮痂病病原菌含量,比对照下降了19．6％～74．9％,且改变了土壤中疮痂病病原菌原有的分布规律：从连作处理的根际多于非根际改变为生物有机肥 GSJ －1处理的根际少于非根际,且对疮痂病的防效达到47．2％。     

云南省马铃薯疮痂病致病链霉菌种类组成研究

 为明确云南省马铃薯疮痂病病原菌(Streptomyces spp.)的种类及其生物学特征,自2013年从云南省13个马铃薯主产区采集疮痂病病样,共分离到200株链霉菌,通过温室盆栽致病性试验筛选出67株致病菌。通过形态学、生理生化指标、致病性测定及16S rDNA序列分析对获得的菌株进行鉴定。结果显示,引起云南地区马铃薯疮痂病的病原为10种链霉菌,分别为S. caviscabies、S. anulatus、S. scabies、S. turgidiscabies、S. acidiscabies、S. europaeiscabiei、S. luridiscabiei、S. enissocaesilis、S. griseus和S. aureofaciens。其中S. enissocaesilis和 S. anulatus为优势种群,S. caviscabies、S. anulatus和S. luridiscabiei为国内首次报道的病原菌。因此,认为云南省马铃薯疮痂病菌种类复杂多样。     

Insecticidal activity of N,N-diethyl-, N,N-dipropyl-, N,n-di-isopropyl-, and n,n-di-isobutylalkanamides against mosquito larvae

N,N-Diethyl-, N,N-dipropyl-, N,N-di-isopropyl, and N,N-di-isobutylalkanamides in which the acyl moiety ranged from C₈ to C₂₁ were synthesised, and their larvicidal activity was determined against the first-instar larvae of the southern house mosquito Culex quinquefasciatus Say. The four homologous series of amides generally showed an increase in their larvicidal activity as the carbon number in the acyl moiety of the amides increased, until the activity reached a maximum. Subsequently, an increment of carbon number resulted in declining activity in the higher homologues, until the activity disappeared. N,N-Diethyltetradecanamide, N,N-dipropylundecanamide, N,N-di-isopropylundecanamide, and N,N-di-isobutlynonanamide or -dodecanamide were the most active compounds in their respective homologous series of amides; however, they were less active than their analogous N,N-dimethylalkanamides previously studied.     

长武旱塬不同麦玉轮作系统产量效应模拟研究

利用EPIC模型对不同麦玉轮作系统进行模拟,通过对其输出结果的分析,综合考虑产量、经济效益、干旱胁迫和氮肥生产率等因素,对不同麦玉轮作系统进行综合评价,从而比较不同麦玉轮作系统的优劣。结果表明:(1)在模拟研究期间,8种麦玉轮作系统的产量均呈波动性下降趋势,其平均值分别为4.61、4.40、4.16、4.48、4.28、4.29、4.714、.55 t/hm2。所有的麦玉轮作系统中,麦玉轮作系统"春玉米→冬小麦"的经济效益最好。(2)在模拟研究期间,麦玉轮作系统"春玉米→冬小麦→冬小麦"的冬小麦和春玉米所遭受的年均干旱胁迫日数最少(29.51d)。在干旱年份麦玉轮作系统中的冬小麦较春玉米更容易遭受干旱威胁。综合产量、经济效益、作物所遭受的干旱胁迫天数和麦玉轮作系统的氮肥生产率等因素,在长武地区适宜采用的麦玉轮作系统为春玉米→冬小麦。     

施肥对小麦、玉米和大豆连作土壤微生物群落功能多样性的影响

为了明确长期施肥和不施肥条件下作物连作对土壤微生物群落功能多样性的影响,以典型黑土为研究对象,选取长期定位实验站长期施肥和不施肥条件下的小麦、玉米和大豆连作处理,通过稀释平板法和Biolog Eco微平板法,测定土壤细菌、真菌、放线菌数量、碳源代谢活性等指标,为建立合理的农田管理措施提供数据支撑和理论依据。结果表明:长期施肥条件下大豆、小麦和玉米连作土壤细菌、真菌和放线菌数量均高于不施肥处理,且均以大豆连作处理细菌和真菌数量最高。不施肥条件下小麦和玉米连作土壤细菌总数较大豆连作处理分别下降了24.8%和31.0%,真菌总数分别下降了64.0%和51.2%;施肥条件下小麦和玉米连作土壤细菌总数则较大豆连作处理分别下降了29.0%和45.5%,真菌总数分别下降了26.7%和31.5%。Biolog结果表明,不施肥条件下小麦连作处理的平均颜色变化率(AWCD)高于玉米和大豆连作处理,施肥条件下则是大豆连作处理的AWCD值高于小麦和玉米连作处理。不施肥条件下大豆、玉米和小麦连作处理利用最多的碳源是碳水化合物类,施肥后不同连作处理利用最多的是碳水化合物类和多聚物类。大豆和小麦连作不施肥条件下土壤微生物利用率最高的碳源均是α-D-乳糖,施肥条件下利用率最高的碳源均是D,L-α-甘油,而不论施肥与否,玉米连作条件下土壤微生物利用率最高的碳源均是D-半乳糖醛酸;葡萄糖-1-磷酸盐和γ-羟基丁酸是农田黑土微生物群落特异利用的关键碳源。主成分分析得出,施肥对土壤微生物碳源代谢能力的影响大于作物的影响。     

东北日光温室葡萄园水热通量特征及其对气象因子的响应

运用温室葡萄水热平衡观测资料，分析了东北日光温室葡萄的能量平衡和能量分量日变化、生育期变化以及分配规律，同时也分析了潜热通量（λET）对环境因子的响应。结果表明：水热通量各分量在整个生育期日变化总体上呈现为单峰趋势，净辐射（R_n）的峰值最大为618.75 W·m^-2，λET峰值最大为242.73 W·m^-2，感热通量（H）峰值最大为327.93 W·m^-2；在新梢生长期，白天λET较小，为34.55 W·m^-2,随着生育期推进，λET逐渐增大，在果实着色成熟期达到最大值（78.49 W·m^-2）之后减小；H在各生育期能量中均占了绝大部分；白天潜热通量占净辐射的比例（λET/R_n）在新梢生长期最小，为25.28%，在果实着色成熟期最大，为44.17%；感热通量占净辐射比例（H/R_n）整个生育期几乎都达50%以上，土壤热通量占净辐射比例（G/R_n）相对较小，变化范围为4.46~12.32 W·m^-2；在整个生育期能量比率大小依次为H/R_n>λET/R_n>G/R_n。在不同生育阶段瞬时尺度上，R_n是影响潜热变化最主要的气象因子，R²高达0.88。在日尺度上，各气象因子对潜热通量的影响在逐渐变弱，相对湿度（RH）与λET相关系数仅为0.28。但无论从瞬时尺度还是日尺度，R_n都是影响潜热通量最主要的气象因子。各气象因子对潜热通量的影响大小依次为：R_n>VPD>T_a>RH。     

Establishment of, and preliminary impact studies on, the rust, Maravalia cryptostegiae, of the invasive alien weed, Cryptostegia grandiflora in Queensland, Australia

The rust fungus Maravalia cryptostegiae , from south-west Madagascar, was introduced into Australia in 1995 as a classical biological control agent against the highly invasive rubber-vine weed Cryptostegia grandiflora , a woody climber endemic to Madagascar. The rust was released at 69 sites between 1995 and 1997 and is now established throughout the plant's exotic range in Queensland, estimated at over 40 000 km². Dispersal was low in the first 3–4 months but was virtually linear thereafter, and the rust spread over 100 km within the first year; after 3 years it was recorded 550 km away from the nearest release site. Spraying both dry and aqueous inoculum of uredinioid teliospores from the ground using mist-blowers, as well as from the air by atomizing spore suspensions, resulted in rust-induced defoliation, producing an overall reduction in fecundity and biomass of the weed. In sites with low water tables, weed growth decreased markedly, with a reduction in plant volume from 9 m⁻³ to 1 m⁻³ over a 4-year period. Both rust- and drought-induced stress combined to cause up to 75% plant mortality at some sites, and at all monitored sites, seedling recruitment was virtually nil. Improved growth of indigenous grasses amongst rubber-vine thickets has increased fuel loads and created opportunities to use fire as a component of an integrated approach to the management of this economically and ecologically damaging weed.     

Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish.     

Comparison of trifluralin,oryzalin, pronamide,propham, and colchicine treatments on microtubules

The mode of action of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), oryzalin (3,5-dinitro-N⁴,N⁴-dipropylsulfanilamide), pronamide(N-(1,1-dimethylpropynyl) 3,5-dichlorobenzamide), and propham (isopropyl carbanilate) on purified microtubules from pig brains and on the ultrastructure of wheat (Triticum aestivum L. “Mediterranean,” C. I. 5303) and corn (Zea mays L. “yellow dent, U. S. 13”) roots was compared with that known for colchicine. Colchicine disrupts the in vivo cortical and spindle microtubules of root cells. Like colchicine, the herbicides trifluralin, oryzalin, and pronamide caused the loss of both cortical and spindle microtubules of root cells. The rate of microtubule disappearance depended on the type of herbicide and length of exposure of roots to the herbicide. Unlike colchicine, cortical microtubules were present in propham-treated roots but they were disoriented within the cell.In vitro polymerization studies with pig brain microtubules (Sus scrofa) showed that the herbicides failed to inhibit the assembly of purified microtubular protein into microtubules and that radioactively labeled herbicides did not bind to the microtubular protein. Colchicine inhibited the polymerization of microtubular protein and readily bound to the microtubular subunits. These results indicate that the mode of action of the herbicides is not similar to that of colchicine and that the loss of microtubules from root tip cells treated with trifluralin, oryzalin, and pronamide may be caused by these herbicides interfering with synthesis of microtubular protein or metabolism of endoplasmic reticulum membranes involved in microtubule assembly. The mode of action of propham appears to be on the microtubular organizing centers rather than on microtubules per se.     

Action of some herbicides on growth,respiration, plasmalemma integrity,and proton extrusion of Acer pseudoplatanus cells: II. Amides,diphenyl ethers,nitriles, phenols,triazines, and uracils

The activity of 15 herbicides from different families was assayed on nonphotosynthetic Acer pseudoplatanus cells, in batch suspension culture. They inhibited growth, stimulated the oxygen consumption by cells, and changed the pH evolution of the culture medium. Amides did not seem to disturb the membrane properties. Some diphenyl ethers and phenols directly modified the proton compartmentation of cells whereas some other diphenyl ethers, nitriles, triazines, and uracils altered permeabilities to potassium and leucine. Changes in membrane permeabilities to protons and medium constituents were discussed.     

Modeling the Risk of Entry, Establishment, Spread, Containment, and Economic Impact of Tilletia indica, the Cause of Karnal Bunt of Wheat, Using an Australian Context

ABSTRACT Modeling techniques were developed to quantify the probability of Tilletia indica entering and establishing in Western Australia (WA), and to simulate spread, containment, and the economic impact of the pathogen. Entry of T. indica is most likely to occur through imports of bulk grain or fertilizer (0.023 +/- 0.017 entries per year and approximately 0.009 +/- 0.009 establishments per year). Entry may also occur through straw goods, new or second-hand agricultural machinery, and on personal effects of travelers who have visited regions with infected plants. The combined probability of entry and establishment of T. indica, for all pathways of entry, is about one entry every 25 years and one establishment every 67 years. Alternatively, sensitivity analysis does show that increases in quarantine funding can reduce the probability of entry to about one entry every 50 years and less than one establishment every 100 years. T. indica is spread efficiently through contaminated farm machinery, seed and soil, rain, air currents, and animals. Depending on the rate of spread of the pathogen and the amount of resources allocated for detection, the time until first detection could range from 4 to 11 years and the economic impact could range from 8 to 24% of the total value of wheat production in WA.     

Effects of pymetrozine, an antifeedant of Hemiptera, on Asian citrus psyllid, Diaphorina citri, feeding behavior, survival and transmission of Candidatus Liberibacter asiaticus

BACKGROUND: Vector‐borne plant disease management can be enhanced by deployment of antifeedants in addition to the use of broad‐spectrum neurotoxic insecticides. The effects of pymetrozine on Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, feeding behaviour, survival and transmission of Candidatus Liberibacter asiaticus (Las), the presumed causal pathogen of huanglongbing, were investigated. RESULTS: Pymetrozine applied at 52 and 104 µg mL^?1 to citrus plants [Swingle citrumelo (X Citroncirus webberi Ingram and Moore)] modified the feeding behavior of ACP and increased the amount of time spent performing non‐penetration behaviors while decreasing the time spent performing ingestion behaviors compared with the controls 1 day after treatment. However, the antifeedant effect of pymetrozine subsided 5 days after application. Pymetrozine reduced the survival of both adults and nymphs on treated plants compared with the control. However, it had a greater impact on survival of nymphs than on survival of adults. Pymetrozine applied at 52 and 104 µg mL^?1 on Las‐infected ‘Valencia’ sweet orange plants [Citrus sinensis L. (Osbeck)] reduced acquisition (12 and 21% respectively) and transmission (11 and 18% respectively) of Las by feeding ACP adults compared with the controls; however, these reductions were not statistically significant. CONCLUSIONS: Pymetrozine exhibited moderate antifeedant effects by modifying the feeding behavior of ACP adults with short residual activity. The impact of pymetrozine on survival of nymphs was greater than on adults at the higher concentrations tested. Pymetrozine also reduced the acquisition and transmission of Las by feeding ACP adults up to 21 and 18%, respectively, compared with untreated controls. Copyright © 2010 Society of Chemical Industry