Interaction between climate and management on beta diversity components of vegetation in relation to soil properties in arid and semi-arid oak forests,Iran

This study aimed to investigate the interaction between regions with different climatic conditions(arid vs. semi-arid) and management(protected vs. unprotected) on the turnover and nestedness of vegetation in relation to physical, chemical and biological properties of soils in the Ilam Province of Iran. In each of the two regions, we sampled 8 sites(4 managed and 4 unmanaged sites) within each of which we established 4 circular plots(1000 m~2) that were used to investigate woody species, while two micro-plots(1 m×1 m) were established in each 1000-m~2 plot to analyze herbaceous species. In each sample unit, we also extracted three soil samples(0–20 cm depth) for measuring soil properties. The results indicated that the interaction between region and conservational management significantly affected the percent of canopy cover of Persian oak(Quercus brantii Linddl), soil respiration, substrate-induced respiration, as well as beta and gamma diversities and turnover of plant species. The percent of oak canopy cover was positively correlated with soil silt, electrical conductivity, available potassium, and alpha diversity, whereas it was negatively correlated with plant turnover. In addition, plant turnover was positively related to available phosphorus, while nestedness of species was positively related to organic carbon and total nitrogen. According to these results, we concluded that physical, chemical, and biological characteristics of limited ecological niche generally influenced plant diversity. Also, this study demonstrated the major contribution of the beta diversity on gamma diversity, especially in semi-arid region, because of the higher heterogeneity of vegetation in this area.     

Characterization and growth conditions of Vibrio parahaemolyticus strains with different virulence degrees that cause acute hepatopancreatic necrosis disease in Litopenaeus vannamei

The phenotypic characteristics and growth kinetics at several temperatures, salinities, and pH values of three Vibrio parahaemolyticus (Vp) strains with different virulence and one nonpathogenic strain were evaluated. Independent of the virulence of the strain, a high metabolic diversity was found, which yielded different colored phenotypes on the CHROMagar? Vibrio. All strains were resistant to ampicillin and carbenicillin, and Vp AHPND+ organisms were the most sensitive to enrofloxacin. The exponential growth of Vp strains started at 1–2 hr of incubation, although no relationship was observed between the bacterial density and degree of virulence. Moreover, the growth of the most virulent strain was independent of the nutrients in the incubation media during the initial hour postinoculation. No strain grew at 4°C in 0% NaCl and pH 4, but only Vp AHPND+ grew at 44°C. For all strains, the lag phase was proportional to the NaCl concentration, and the growth was better at pH 8–9. However, the Vp AHPND? strain displayed a greater variability, was more sensitive to extreme conditions, and showed a lag phase of 9 hr independent of the pH.     

固态热带假丝酵母菌菌剂的发酵工艺研究

试验在单因素优化试验的基础上,采用正交试验进一步对热带假丝酵母菌固态发酵工艺进行研究,包括发酵时间、接种量、料水比、碳源、氮源、无机盐等因素,最终确定热带假丝酵母菌的固态发酵工艺。发酵条件:在自然pH值条件下,发酵温度30℃、发酵时间48 h、接种量11%、料水比1∶0.75。培养基成分:麸皮与甘油8.5∶1.5 (g/g)、尿素0.5%、磷酸二氢钾0。依照此工艺进行发酵,热带假丝酵母菌活菌数最高可达32.94×10⁸个/g。     

菜地土壤中纤维素降解菌的筛选及其产酶条件优化

利用传统的微生物学方法,从菜地土壤中筛选出高产纤维素酶的菌株,并对其产酶条件进行优化。结果表明,从4种菜地土壤中共分离获得16株纤维素降解菌,其中生菜地土壤中获得的菌株最多,白菜地土壤中获得的菌株最少;在16个菌株中,从油菜地中分离纯化的1个菌株具有最强的纤维素降解能力;对该菌株的产酶条件优化发现,以麸皮作为唯一碳源、培养温度35℃、培养时间96 h时酶活力最高。     

不同播期夏播小豆产量性能动态指标与光温水效应

为探讨光、温、水等气象因子对夏播小豆产量的影响，达到合理利用气象资源、进一步挖掘小豆增产潜力的目的，以中晚熟小豆品种花小豆（V₁）和中早熟品系德红5261（V₂）为材料，设T₁（6月17日）、T₂（6月22日）、T₃（6月27日）、T₄（7月2日）和T₅（7月7日）5个播期，形成不同的光、温、水生长环境，对夏播小豆产量性能指标和光、温、水因子效应及气象因子资源量在小豆生育前期与后期的比值（分配率）进行测定和分析。结果表明，小豆产量、单株荚数和单株粒重随播期推迟先增加后逐渐降低，各播期的大小依次为：T₂>T₁>T₃>T₄>T₅，品种间产量差异极显著，V₂>V₁，每荚粒数和百粒重受播期影响较小；随着播期的推迟，小豆的生育天数、平均叶面积指数、总光合势逐渐减小，但收获指数相应增加。光、温、水因子对产量性能指标有明显的正负调节效应，V₁生育前期有效积温与产量、平均叶面积指数、生育天数、总光合势和平均作物生长率呈极显著正相关，与收获指数和平均净同化率呈极显著负相关；生育前期降水量与单位面积荚数呈极显著正相关；生育前期日照时数与平均叶面积指数、总光合势和平均作物生长率呈极显著正相关，与平均净同化率呈极显著负相关；生育后期有效积温与平均作物生长率呈显著正相关；生育后期日照时数与总光合势呈显著正相关。V₂生育前期有效积温与产量、单位面积荚数、平均叶面积指数、总光合势和平均作物生长率呈极显著正相关，与收获指数呈极显著负相关；生育前期降水量与平均叶面积指数和平均作物生长率呈显著负相关；生育前期日照时数与生育天数和总光合势呈极显著正相关，与产量呈显著正相关，与收获指数和每荚粒数呈极显著负相关；生育后期有效积温与平均叶面积指数、生育天数和总光合势呈极显著正相关，与收获指数、每荚粒数和百粒重呈极显著负相关；生育后期降水量与平均作物生长率呈极显著正相关。对气象因子资源量分配与小豆产量进行回归分析，得出不同小豆品种获得最高产量的最佳光、温、水资源量在生育前、后期的比值（分配率）及其组合，V₁为：生育天数1.86、有效积温2.27、降水量49.73、日照时数1.45；V₂为：生育天数1.45、有效积温1.49、降水量1.57、日照时数0.98。在德州地区，夏播小豆选用中早熟品系V₂在6月20日前后播种，生育期内光、温、水资源量的分配率及其组合最佳，可获得较高的产量。     

开封市公共气象服务发展探讨

公共气象服务是为政府决策、民生发展提供的一项基础性公共事业。该文通过阐述开封市公共气象服务发展的现状,对比国内气象服务工作,分析其中存在的问题,以充分发挥气象服务的社会效益、经济效益。     

盐肤木施肥效应及角倍蚜营养环境初步研究

对盐肤木叶片成分分析结果表明 :寄生角倍的叶片与正常叶片相比 ,叶组织内的氨基酸和Vc的浓度由 11.0 6 % ,1.15 %降低到 7.85 %和 0 .6 8% ,幅度很大 ;总N和单宁的浓度也略有降低 ,而可溶性总糖的浓度则稍有升高。通过盆栽施肥试验得出 :N、P肥不但可促进盐肤木幼树生长 ,并影响叶片内Vc的含量 ,但对叶片内的可溶性糖、单宁及总氮含量没有明显的影响 ;施N肥对叶组织的碳氮比(C/N)的作用较P肥明显     

EMDI-UF混合胶刨花板制造工艺条件的研究

介绍了东北林业大学人造板研究所在降低人造板游离甲醛释放量的研究成果,利用可乳化异氰酸酯(EMDI)与脲醛树脂(UF)混合胶制造刨花板,使产品达到E1级标准要求。研究结果表明:混合胶的施胶量为7％,采用6％的UF和1％的EMDI是比较适合的比例。将它们混合到一起,不加酸性固化剂,搅拌均匀后喷洒到刨花上,比较适宜的板坯含水率不应超过14％,在175℃下热压4.5min,所粘结的刨花板各项性能都符合GB4897—92—等品和E1级板标准的要求。与UF胶刨花板相比,混合胶刨花板的耐水性得到明显改善,甲醛释放量可降低到7.88mg/100g板。     

乌天麻与红天麻在自然条件下花期相遇调控技术

在自然条件下,乌天麻和红天麻花期相差20~30 d,在相同条件下试验栽培,乌天麻和红天麻花期相差7~8 d.通过利用薄膜小棚和海拔高差,调控乌天麻与红天麻发育过程,促其花期相遇并获得成功,且调控成本比室内加温低,实用性强,为乌天麻和红天麻杂交育种开辟了一条新途径.