冬枣贮期浆胞病病原菌鉴定及病害生理研究

冬枣贮期主要病害是浆胞病,经病原菌鉴定,属半知菌类交链孢霉菌。-2℃的低温只能抑制而不能终止该菌的生长。pH值在5~9的范围内,菌落生长和孢子繁殖良好,pH值低于5和高于9时生长缓慢;在含有3.0 mg/mL壳聚糖的PDA培养基上,病原菌菌落生长抑制率可达88.23%,将其浓度与菌落直径抑制率分别取对数后,二者存在正相关性,相关系数R=0.964 6;臭氧和减压均能抑制该病原菌孢子的繁殖,臭氧浓度为300mg/m3时对孢子繁殖抑制率达75.80%,40 kPa的压力对孢子繁殖抑制率为59.22%。     

Performance of Soil Electrical Conductivity and Different Methods for Mapping Soil Data from a Small Dataset

The performance of different methods for making soil maps from a small dataset was assessed. Soil samples obtained at five different depths were taken from 39 locations within an arable field in Sweden and analysed for clay content, soil organic matter content, pH (H₂O), K-HCl, P-AL, K-AL and Mg-AL. Detailed and densely sampled soil electrical conductivity (EC) data with a distinct border between two different regions was used for dividing the field into two zones. Averages from these zones gave better prediction for most variables than interpolation without respect to the border. With the border taken into account, cokriging with EC as a covariable improved the prediction, whereas the improvement with ordinary kriging and inverse distance weighting (IDW) was insignificant. Direct interpretation of EC by a simple linear regression model gave reasonable predictions for clay content. In general, even the simplest interpolation method improved the prediction compared to field average.     

松散地面上车辙表面的非接触式激光测量

车辙表面原始形貌数据对深入研究车轮与松散地面相互作用机理具有重要意义.为了快速准确地获得土槽试验中松散地面上车辙表面原始数据,设计了带有二维移动框架的激光扫描仪,该装置的最大扫描面积是650mm×400 mm,测距范围为0.05 ～ 65 m,扫描分辨率为0.lmm.在此基础上设计出带有一维移动框架的激光扫描仪,以满足月球车内场试验中快速测量车辙表面形貌的要求.对土槽试验与月球车内场试验中的车辙表面进行测量,试验结果表明所设计的激光扫描仪能够使用非接触测量方法在不扰动车辙的条件下获得车辙表面形貌的纵向断面图和三维图形.     

Competition effects in an afrotemperate forest

Background： Information about competition responses is mainly available for monospecific stands or mixed stands with a small number of species. Studies on complex multi-species and highly structured forest ecosystems are scarce. Accordingly, the objective of this study was to quantify competition effects and analyse competition responses in a species-diverse afrotemperate forest in South Africa, based on an observational study with mapped tree positions and long-term diameter increment records. Methods： The sensitivity to competition was analysed for individual species and involved the calculation of the slope of the linear relation between the value of a competition index （CI） and diameter growth as a measure of sensitivity. In a next step different competition indices were combined and tree diameters were grouped in three classes as surrogates for canopy status and ontogenetic stage. Results： Five competition indices were found to be effective in showing sensitivity to competition for a number of canopy and sub-canopy species. Significant linear regressions were fitted for 18 of a total of 25 species. Species reactions varied significantly in their sensitivity to the different CIs. The indices were classified as belonging to two groups, those that responded more to local crowding and those that are more sensitive to overtopping, which revealed species-specific sensitivities to both factors. The analysis based on diameter classes revealed that species clearly changed their sensitivity to crowding or overtopping depending on diameter. Canopy and sub-canopy species showed distinct differences in their reactions. Conclusions： The application of multiple CIs brought novel insights relating to the dynamics of afrotemperate forests. The response patterns to different competition indices that focus on crowding and overtopping are varied and tree diameter dependent, indicating that oversimplified assumptions are not warranted in the interpretation of Cl- growth relations.     

Impact of thermal modification on bioresistance of North American wood species,Pinus banksiana,Populus tremuloides,and Betula papyrifera,against wood-rotting basidiomycete fungi

In this study, the decay resistance of untreated and thermally modified jack pine (Pinus Banksiana), aspen (Populus tremuloides), and white birch (Betula Papyrifera) was evaluated. Wood specimens were exposed to laboratory decay resistance tests using the wood-rot fungi, Trametes. versicolor, Poria placenta, and Gloephyllum trabeum for 2–12 weeks of incubation.

The results indicated that, T. versicolor fungus was virulent against all the three untreated woods, B. papyrifera (73.9% weight loss), P. tremuloides (57.1% weight loss), and P. banksiana (43.5% weight loss). P. placenta fungus affected B. papyrifera (52.4% weight loss), P. banksiana (52.3% weight loss), and P. tremuloides (36.7% weight loss). G. trabeum fungus was virulent against P. banksiana (41.53% weight loss), but less active against B. papyrifera (11.6% weight loss) and P. tremuloides (21.9% weight loss).

It was found that the weight losses due to T. versicolor fungus activity were reduced for P. banksiana (1.5% weight loss) thermally modified at 210 °C, B. papyrifera (27.9% weight loss) at 215 °C, and P. tremuloides (9% weight loss) at 220 °C compared to the weight losses of their untreated counterparts. These correspond to 96.5%, 62.2% and 84.2% of decrease in weight loss, respectively. Similar results were obtained with G. trabeum fungus. On the contrary, thermal modification on the deterioration of P. banksiana (39.1% weight loss) by P. Placenta was affected less resulting in only 25.2% weight loss relative to untreated wood.     

新疆哈密瓜采后主要致腐病原真菌的分离与鉴定

通过对新疆哈密瓜采后贮藏中发病的果实进行病原真菌的分离,以及对冷藏中健康的果实进行潜伏侵染的真菌进行分离,鉴定后确定新疆哈密瓜采后主要致腐病原真菌为:根霉属(Rhizopus);镰孢属(Fusarium);链格孢属(Alternaria);青霉属(Penicillium)。     

马尾松N_2热处理材耐腐性能及化学性质的研究

采用均匀设计法探讨氮气(N2)热处理工艺对人工林马尾松木材耐腐性能及化学性质的影响。结果表明,随处理温度升高,保温时间增加,木材耐腐性能提高;N2热处理使其纤维素含量减少0.9%,半纤维素减少6.5%。红外光谱分析(FTIR)表明,N2热处理使木材内部O—H减少。马尾松N2热处理的较佳工艺条件:处理温度220℃,保温时间4 h,升温速率15℃.min-1,此时处理材腐朽后失重率16.4%,已达到Ⅱ级(耐腐)。     

海藻多酚处理对采后草莓腐烂与贮藏品质的影响

以鼠尾藻为原料提取多酚,研究海藻多酚处理对采后草莓腐烂的控制与贮藏品质的影响。结果表明,鼠尾藻海藻多酚单体组成主要为儿茶素、表儿茶素、儿茶酚、阿魏酸和芦丁,其质量浓度分别为1.95,9.60,43.98,0.63,0.23 mg/mL。总酚质量浓度为16 mg/mL的鼠尾藻提取物可100%抑制草莓灰霉菌(Botrytis cinerea)的生长。新鲜草莓经质量浓度10 mg/mL的海藻多酚处理并于(2±1)℃,90%~95%RH贮藏12 d后,其腐烂率和腐烂指数分别比对照低61.6%和52.5%,草莓硬度、可溶性固形物及VC含量均明显高于对照(p<0.05)。在常温刺伤接种和冷藏不接种Botrytis cinerea 2种条件下,海藻多酚处理的草莓苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)活性均明显高于对照(p<0.05)。结果表明,海藻多酚不但具有直接抗菌活性,可控制草莓的采后腐烂,而且能诱导草莓的采后抗病性,提高抗病相关酶活性,从而降低草莓果实的腐烂,保持草莓品质。     

木材褐腐过程中化学组成对其液化的影响

为了探明木材腐朽程度引起的化学组成变化规律与液化特性之间的关系，该文利用褐腐真菌茯苓对马尾松木材进行不同程度的生物降解预处理，用残渣率指标、GPC、FTIR和NMR对木材的液化程度及液化产物特征进行了表征。结果表明:褐腐木材在液比为2和磷酸催化条件下可取得良好的液化效果。对褐腐木材而言，随腐朽时间从3周延长至7周，液化残渣率逐渐降低，液化产物中残留的苯酚量逐渐减少，液化产物的分子量和分子量分布逐渐增大。当腐朽时间达到11和15周时，残渣率迅速下降，分子量和分子量分布继续呈上升趋势，而残留的苯酚量却有微弱的增加。说明褐腐处理的木材比正常木材在苯酚中的液化条件温和，木材腐朽程度越严重，液化反应越容易，腐朽时间11周(1％NaOH抽出物含量为54％)是木材在苯酚中的液化反应由难到易的转折点。FTIR和NMR结果显示:腐朽木材与苯酚的酚化反应主要发生在酚羟基的邻位和对位，且以单取代为主，木材组分通过酚化反应转化为含有活性部位的酚类物质。      

稻/菰远缘杂交后代变异材料MITE类转座子mPing的激活

实验以日本引进粳稻品种松前为受体材料,以水稻的近缘属菰为供体,利用花粉管通道法导入受体水稻菰的基因组DNA。经过两个世代的培养,T1世代表型（株形、穗形、籽粒特征）变异不明显,但统计分析结果表明生育期及有效分蘖数与母本有显著差异。在T2世代发现明显的表型变异株,并且此变异后代类型丰富。随机选取22个表型变异株进行Southern杂交和转座子分析,发现MITE类转座子mPing发生了转座激活。根据日本晴的基因组序列设计了含有mPing的特异位点引物以及用TAIL-PCR方法检测到了T2世代中mPing的跳出及插入频繁。实验获得了水稻的优良变异后代,扩大了遗传资源,丰富了生物多样性。研究结果为远缘杂交在基因组进化和作物遗传改良中的可能作用提供了新的理论依据。