青枯菌胞外酶对木麻黄的致病作用研究

对三个致病性不同的木麻黄青枯菌Ｐｓｅｕｄｏｍｏｎａｓ ｓｏｌａｎａｃｅａｒｕｍ Ｅ．Ｆ．Ｓｍｉｔｈ产生的胞外酶活性测定显示,聚半乳糖醛酸酶（果胶酶）在活性在各菌之间无明显差别,但纤维素酶活性差别明显,并随菌株的致病性上升而增加,菌株致病性与酶活性具有高度正相关。     

白僵菌对球果花蝇致病性研究

四株分离自土栖害虫的球孢白僵菌Ｂｅａｕｖｅｒｉａｂａｓｓｉａｎａ对危害落叶松的球果花蝇Ｓｔｒｏｂｉｌｏｍｙｉａｓｐｐ．致病性室内试验表明，分离自球果花蝇的菌株对该虫有较强的致病性；球果花蝇不同虫态对白僵菌球果花蝇品系的易感性为：老熟幼虫＞成虫＞蛹，感病的老熟幼虫多数在蛹期出现病症；生物测定老熟幼虫感病死亡率可达８１．３％；土壤处理施菌浓度１ｇ／ｍ２（含孢量为５０亿孢子／ｇ）以上时，校正死亡率为６４．７—８１．１％。     

湖北省湿地松猝倒病病原的分离及鉴定

从湖北沙洋、松滋、红安三地常年培育湿地松的苗圃中取土于室内种植湿地松,待其发病后按照柯赫氏法则对其进行病原物的分离、纯化、致病性测定及菌株鉴定。结果表明：发病部位分离到的菌株以镰孢菌（Fusarium spp．）占优势,分离到的68个菌株中65个为镰孢菌;立枯丝核菌（Rhizoctonia solani Kühn．）致病性最强,7天后发病率达到92％;链格孢（Alternaria alternate（Fr．）Keissl．）致病性最弱。研究证明,湖北省湿地松猝倒病是以镰刀菌为主要病原,立枯丝核菌和链格孢菌为次要病原的土壤习居真菌侵染引起的一种苗期病害。     

白僵菌对球果花蝇致病性研究

四株分离自土栖害虫的球孢白僵菌Ｂｅａｕｖｅｒｉａｂａｓｓｉａｎａ对危害落叶松的球果花蝇Ｓｔｒｏｂｉｌｏｍｙｉａｓｐｐ．致病性室内试验表明，分离自球果花蝇的菌株对该虫有较强的致病性，球果花蝇不同虫态对白僵菌球果花蝇品系的易感性为：老熟幼虫〉成虫〉蛹，感病的老熟幼虫多数在蛹期出现病症；生物测定老熟幼虫感病死亡率可达８１．３％，土壤处理施菌浓度１ｇ／ｍ＾２（含孢量为５０亿孢子／ｇ）以上时，校正死亡率为６     

木麻黄青枯病菌(Pseudomonas solanacearum E.F.Smith)毒性菌株的筛选

接种实验发现,木麻黄青枯病菌存在着强致病性、弱致病性、非致病性菌株之分。致病性不同的三个菌株进行电镜观察,菌体在形态上存在差别;不同菌株的培养性状观察,菌落在形状、颜色、流动性上有差别。毒性菌株保存实验结果以在无菌蒸馏水中室温保存为好,二年不丧失致病性,分离毒性菌从病苗上比从成年发病株上容易。     

桉树青枯菌菌株致病性分化与其菌量增殖及胞外多糖产量的联系

通过对桉树无性系剪根苗接种青枯菌Ralstonia solanacearum2个菌株后测定菌株的致病性、茎内的细菌数量得到，两菌株具有明显的致病性分化，强致病性菌株在剪根苗基部、中、上部的细菌数量都显著高于弱致病性菌株；2个菌株的细菌数量从茎基部到上部呈逐渐降低的趋势，木质部的含菌量比韧皮部高。通过提取和测定2个菌株胞外多糖（EPS）产量得到，强致病性菌株EPS的总产量及单个细菌EPS产量都高于弱致病性菌株。试验揭示青枯菌菌株的致病性分化与其在桉苗茎内的增殖扩散数量及其EPS的产量有着一定联系。     

中国松树枯梢病菌遗传多态性的RAPD分析

运用随机增增多态ＤＮＡ（ＲＡＰＤ）技术对发生于我国１３省区１６种松树和其它２种针叶树上的松枯梢病菌（Ｓｐｈａｅｒｏｐｓｉｓ ｓａｐｉｎｅａ）的５５个菌株进行基因组ＤＮＡ多态性分析。用１７个随机引物经ＰＣＲ扩增共得到２００个ＲＡＰＤ标记,其中９８．５％具有多态性。ＵＰＧＭＡ聚类分析确定了供试菌株间的亲缘关系,将５５个菌株分为３个类群。各菌株间的差异与其寄主种类无明显关系,与其地理来源在某些类群间有一定联系,但在大多数菌株间相关趋势不明显。     

不同含水量球孢白僵菌孢子抗逆性研究

影响球孢白僵菌（Ｂｅａｕｖｅｒｉａｂａｓｉａｎａ（Ｂａｌｓ．）Ｖｕｉｌ．）的贮藏的环境稳定因素主要为环境温度及紫外光。孢子含水量高低影响虫生真菌菌株的耐热性,金龟子绿僵菌（Ｍｅｔａｒｈｉｚｉｕｍａｎｉｓｏｐｌａｅ（Ｓｏｒｏ．））在３０ｍｉｎ内的半致死...     

桉树青枯病病原菌的分子鉴定及其致病性测定

对华南4个地区的桉树青枯病病原菌进行了分子鉴定和致病性测试研究,以期为有效预防其发生提供依据.分别对来源于不同区域的11株桉树青枯病病原菌进行分子鉴定和致病力强弱测试比较,11株病原菌与Ralstonia solanacearum序列形成支持率为86％分枝,表明其病原菌16S rRNA基因序列与Ralstonia solanacearum具有高度同源性.以桉树无性系DH32-29组培苗为材料,采用伤根法对11个菌株进行致病力测试,不同菌株间在致病性上差异显著(P＜0.01或P＜0.05),以发病高峰期、高峰期发病率和平均发病率进行K-均值聚类分析(K=3),结果表明来源于广东、广西、海南的各菌株间致病性存在差异,HY01、HY02、DA01、HP04菌株与HP05分为1类,DA02和DA03为第2类,而YJ01、HP01、HP02和HP03为第3类.对4个不同地区(采样点)的青枯病菌株平均发病率进行方差分析,结果发现来源广东阳江菌株致病性显著地低于其他来源菌株.不同地理来源菌株之间在致病性上无明显相关性,同一地区内同时存在着致病力强弱菌株,HP03的生物型4-1菌株与其他生物型3菌株在致病性亦无明显的差别.     

杨树人工林地力退化及维护与提高土壤肥力技术的研究

在山东，辽宁，河南，河北，北京等五个杨树（ＰｏｐｕｌｕｓＬ．）栽培地区，抽样调查４８块样地，并进行土壤养分化学分析，研究了杨树同代纯林，一代林、二代林生长对林地土壤肥力的影响以及杨树与刺槐（ＲｏｂｉｎｉａｐｓｅｕｄｏａｃａｃｉａＬ．）、沙棘（ＨｉｐｐｏｐｈａｅｒｈａｍｎｏｉｄｅｓＬ．）、紫穗槐（ＡｍｏｒｐｈａｆｒｕｔｉｃｏｓａＬ．）、混交对土壤营养元素含量，土壤微生物数量，土壤酶活性等方面的影响。研究表明，在相同立地条件下，杨树同代林，随林木生长，土壤养分含量有下降趋势；连栽二代纯林比一代纯林，土壤养分含量及林木生长量有明显下降趋势；杨树与刺槐、紫穗槐、沙棘混交，能够提高土壤肥力，促进林木生长，是维护与提高土壤肥力，防治杨树人工林地力退化的有效生物措施。     

茶树不同器官氨同化关键酶活性测定及比较

为取得茶树氨同化关键酶活性的最优测定方法,以4个茶树品种的不同器官为材料,比较和讨论了不同器官间和品种间氨同化关键酶活性,对Tris-HCl缓冲液不同pH值的条件下提取的氨同化关键酶活性分析比较,得出缓冲液对酶活性的影响以及4个茶树品种的最适宜pH值。结果表明缓冲液的pH值对茶树顶芽、当年生叶、2年生叶以及根系的酶活性影响极显著,并且均以缓冲液pH值为7.0时得到的酶活性较高。4个器官的GS活性基本上是随缓冲液pH值的升高而增强,并且在pH7.0和7.5时处于较高水平;4种器官的GOGAT活性则是随pH的升高呈现"下降-上升-下降"的变化,当年生叶和2年生叶片的GOGAT活性在pH6.0时最低,之后开始上升,根系和顶芽则是在pH6.5时最低。主成分分析结果表明,缓冲液pH7.0是研究4个茶树品种4个器官氨同化酶活性的最优pH值。品种间GS活性差异显著,GOGAT活性差异极显著;器官间GS和GOGAT活性差异均极显著。     

北京低山地区土壤酶活性与土壤理化性质的关系

通过对北京低山地区土壤的理化性质和脲酶、过氧化氢酶以及多酚氧化酶的分析，探讨了供试土壤中３种酶活性状况及其与土壤理化性质的关系。研究结果表明：３种土壤酶活性均表现出随土壤深度增加而降低的规律性；３种土壤酶活性间具有良好相关性，显示了３种酶在土壤生物化学过程中的共性关系；土壤酶活性同多种土壤性质呈现良好相关性，其中，土壤有机质含量和土壤全氮量对酶活性影响最大。     

桉树等植物吲哚乙酸氧化酶活性变化与插条生根的比较研究

对４种桉树和易生根的山指甲、一品红、福建茶插条吲哚乙酸氧化酶活性变化与生根的关系研究结果表明，容易生根的植物体内ＩＡＡ氧化酶活性较低，难生根的植物ＩＡＡ氧化酶活性都较高。同一植物枝条的不同切段，体内ＩＡＡ氧化酶活性差别较大，近顶端部分酶活性较低，离顶端较远的部分酶活性依次升高。各植物的ＩＡＡ氧化酶活性均表现季节性差异，不同植物有各自的表现规律。插条扦插后，体内的ＩＡＡ氧化酶活性有逐渐升高的趋势。本     

不同抚育措施对油茶林土壤养分 微生物及酶活性的影响

对常宁地区不同抚育措施油茶林的土壤养分、微生物及酶活性进行了测定和分析。结果表明:各林分间土壤养分、微生物数量和酶活性存在较大差异。同一林分土壤养分、微生物数量和酶活性随取样深度的增加逐渐降低。锄抚林地在土壤养分、微生物总数和酶活性方面明显高于未抚育和刀抚林分。相关分析表明,这3种林分的土壤养分(有机质、全氮、碱解氮和速效磷)与微生物数量及酶活性之间存在相关关系;细菌数量和脲酶活性与土壤有机质、全氮、碱解氮和速效磷等主要养分指标呈显著或极显著正相关;过氧化氢酶和蔗糖酶活性与土壤养分指标间相关性不强。     

Cellulolytic activity and virulence of Ophiostoma ulmi and O. novo‐ulmi isolates

The cellulolytic activity (exoglucanase, endoglucanase and β‐glucosidase) of Ophiostoma ulmi (four isolates), O. novo‐ulmi (19 isolates) and ‘fast‐waxy’ (five isolates) was determined in growth media containing carboxymethylcellulose (CMC) and cellulose powder. Differences in enzyme activities were observed among isolates, irrespective of the species and substrate used. Inoculation experiments on Ulmus minor with randomly selected isolates of O. ulmi (two isolates), O. novo‐ulmi (five isolates) and ‘fast‐waxy’ (two isolates) were also performed. Disease was assessed as the percentage of leaves showing yellowing and browning. Ophiostoma novo‐ulmi and ‘fast‐waxy’ isolates exhibited a great variability in their capacities to cause the disease. In the presence of CMC, a significant correlation between the activity of exoglucanase and β‐glucosidase in vitro and virulence was found.     

滨海盐碱地刺槐臭椿混交林土壤酶活性季节动态研究

研究了刺槐、臭椿纯林及其混交林中不同土层在不同季节土壤酶活性的变化。结果表明:各林分间的土壤酶活性在各个季节和土层均表现出差异。经统计分析,土壤酶活性在土层中的分布有一定的规律性,总的来说,随着土层逐渐加深,土壤酶活性逐渐减弱。在树木生长表现和土壤酶活性发挥方面,混交林优于纯林。     

Characterization of Canadian isolates of Chondrostereum purpureum by protein content,API ZYM and isozyme analyses

Seventeen isolates of Chondrostereum purpureum, collected from New Brunswick, Vancouver Island, and south-eastern British Columbia, Canada, were compared to determine the degree of genetic variation among isolates from different host species and different biogeographic locations. Several characteristics, including mycelial protein content, fungal biomass, API ZYM profile (semi-quantitative assay to detect the presence of 19 different enzymatic activities in an organism), and isozyme patterns were measured in these isolates. All 17 isolates shared similar API ZYM profiles, with only minor variation observed in the level of expression of specific enzymes. Of the 13 isozyme systems examined, eight (acid phosphatase, alkaline phosphatase, β-esterase, β-glucosidase, malate dehydrogenase, peroxidase, phosphoglucomutase, and polyphenoloxidase) produced measurable activity. No qualitative differences were observed between the isolates for all of these enzymes. There appeared to be limited variation between the isolates collected from across Canada and there was no correlation between specific API ZYM, and isozyme patterns and either host plant or geographical source of the isolates.     

Variation of soil enzyme activity and microbial biomass in poplar plantations of different genotypes and stem spacings

To improve the productivity of poplar plantations, a field experiment of split-plot design with four tree spacings and three poplar clones was established, and four soil enzyme activities and microbial biomass were monitored in the trial.Soil enzyme activities, in most cases,were significantly higher in topsoil(0–10 cm) than in lower horizons(10–20 cm).Soil cellulase, catalase and protease activities during the growing season were higher than during the non-growing season, while invertase activity followed the opposite trend.Soil invertase, cellulase and catalase activities varied by poplar clone but soil protease activity did not.Cellulase and protease activities in the plantation at 5×5 m spacing were significantly higher than in the other spacings.The highest catalase activity was recorded at 6×6 m spacing.At the same planting density, invertase activity was greater in square spacings than in rectangular spacings.Soil microbial biomass was also significantly affected by seedling spacing and poplar clone.The mean soil MBC was significantly lower in topsoil than in the lower horizon, while MBN showed the opposite pattern.Significantly positive correlations were observed among soil cellulase, protease and catalase activities(p0.01), whereas soil invertase activity was negatively and significantly correlated with cellulase, protease and catalase activities(p0.01).Soil microbial biomass and enzyme activities were not correlated except for a significantly negative correlation between soil MBC and catalase activities.Variations in soil enzyme activity and microbial biomass in different poplar plantations suggest that genotype and planting spacing should be considered when modeling soil nutrient dynamics and managing for long-term site productivity.     

杨树混交林地土壤微生物与酶活性的变异研究

对北京大兴县林场和河南省民权国营林场２块试验林，面积分别为１．８６ｈｍ￣２和３．２ｈｍ￣２，连续四年（１９９２－１９９５）进行土壤微生物与酶活性定位观测和定量分析，研究杨树不同混交模式土壤微生物和土壤酶活性的变异及其对土壤营养元素含量和林木生长的影响。结果表明：（１）杨树混交可以提高林地土壤微生物数量，５种处理间存在差异（Ｐ＝７９％）。（２）不同混交处理，土壤酶活性存在差异（Ｐ＝８７％），其中转化酶、磷酸酶在Ａ、Ｃ处理中增长较明显；５种酶活性之间差异极显著（Ｐ＞９９％）。（３）杨树混交林的土壤营养元素、土壤微生物、酶活性与林地生产力关系密切。