紫外分光光度法测定啤酒大麦籽粒脂氧合酶活力的研究

为了明确影响啤酒大麦籽粒脂氧合酶(LOX-1)活力的参数,以甘啤4号啤酒大麦籽粒为研究对象,采用紫外分光光度法探究底物浓度、提取缓冲液p H、反应体系缓冲液p H、提取时间、粗酶加入量∶底物加入量等对LOX-1活力的影响。结果表明,LOX-1活力随底物浓度的增加表现为先增加后减小的趋势,当底物浓度达到0.30mmol·L~(-1)时,LOX-1活力显著高于其它处理;随提取缓冲液p H的增加,LOX-1活力表现为双峰变化趋势,且在p H值5.0处,酶活力为9.85U·g~(-1),显著高于其它处理;粗酶提取时间为30min时,LOX-1活力显著高于其它处理,低于或者高于30min,酶活力均呈现降低趋势;LOX-1活力随反应体系p H的增加,表现为双峰变化趋势,当p H值为6.4时,酶活力最大,且与其它处理间存在显著差异;在其它条件不变,粗酶加入量为50μL的情况下,增加底物加入量,LOX-1活力表现为先增加后减小的趋势,且底物加入量为200μL时,酶活力显著高于其它处理。最终确定紫外分光光度法的测定参数:粗酶提取时间为30min,底物浓度为0.25mmol·L~(-1),提取液和反应体系缓冲液分别为p H值5.0醋酸盐缓冲液与p H值6.4磷酸盐缓冲液,粗酶加入酶量∶底物加入量为1∶4。研究结果为紫外分光光度法在啤酒大麦籽粒LOX-1活力测定中的应用提供了参考。     

丝胶蛋白抗氧化肽的酶法制备及功能评价

为进一步开发利用废蚕丝,充分挖掘丝胶蛋白的可利用程度,该文研究了6种蛋白酶水解制备丝胶肽及产品的抗氧化活性。筛选出Alcalase碱性蛋白酶为制备丝胶抗氧化肽的理想蛋白酶,并以ABTS体系评价了丝胶肽的抗氧化活性。通过单因素试验研究了反应时间、底物浓度、反应温度、pH值、酶底物比对酶水解制备丝胶肽的影响;并通过回归正交旋转试验设计对水解条件进行优化,建立各因素与水解度和抗氧化活性的数学模型,确定Alcalase酶水解丝胶蛋白的最佳水解条件为:反应时间240min,底物浓度2%,反应温度55℃,pH8.5,酶底物比2.375%。最佳水解条件下水解度为33.35%,ABTS清除活性为43.19%。该研究为开发丝胶抗氧化肽功能产品提供了技术依据。     

胰蛋白酶对壳聚糖的降解研究

用粘度法和吸光度法，研究胰蛋白酶非专一性降解壳聚糖过程中温度、PH值、反应时间、酶浓度、底物浓度。金属离子对胰蛋白酶降解壳聚糖反应的影响，确定了以壳聚糖为底物的胰蛋白酶的一些催化特性：最适温度为30℃，最适PH值为5.0,10-180min内酶反应速度恒定，酶浓度在0.1-0.5g/L的范围内，酶反应速度与酶浓度呈线性关系，米氏常数Km为9.54g/L。     

重组多功能木聚糖酶酶解条件的优化

重组多功能木聚糖酶(recombinant multi-functional xylanase,RMFXase)是以草菇为表达载体,具有多种酶活力的新型酶。为揭示该酶与底物的作用规律,同时为转基因酶的应用提供基础数据,该文利用重组多功能木聚糖酶水解南方特色的甘蔗加工废弃物生产低聚木糖,通过响应面法建立以重组多功能木聚糖酶质量浓度、底物质量浓度和酶解时间为控制因素的反应动力学方程组,从而推导得到酶解最佳工艺参数。试验并通过高效液相色谱法法,监测反应过程中产物的动态变化,分析产物的生成规律。结果表明,通过响应面法推导出符合连续式酶解反应器的最佳酶解工艺参数为:加酶量900 U/mL、底物质量浓度110 mg/mL、反应时间80 min。该条件下酶解木聚糖含量为54.7%的蔗渣半纤维素,得到的低聚木糖DP值达到3,酶解率达到23.94%。酶解过程中重组多功能木聚糖酶表现出高内切-β-1,4-木聚糖活力,优先降解大分子木聚糖,后期产物主要以木二糖和木三糖为主,且底物纯度越高,底物利用率越高。     

供磷水平对平邑甜茶幼苗NO3-吸收、利用特性的影响

运用~(15)N示踪及非损伤微测技术,研究了不同供磷水平(0 mmol×L~(-1)、1.0 mmol×L~(-1)、2.0 mmol×L~(-1)、3.0 mmol×L~(-1)、4.0 mmol×L~(-1)、6.0 mmol×L~(-1)、8.0 mmol×L~(-1)、12.0 mmol×L~(-1)和16.0 mmol×L~(-1) H_2PO_4~-)对平邑甜茶幼苗NO_3~--N吸收及利用特性的影响,为提高果园氮肥利用效率提供理论依据。结果表明,在低磷水平(0~1.0 mmol×L~(-1))时,平邑甜茶根系长度、根系总表面积较小,且根尖数较少。随着供磷水平的增加,在2.0~4.0 mmol×L~(-1)磷浓度处理时,平邑甜茶幼苗生物量、根系长度、根系总表面积及根尖数显著高于其他处理。而在6.0~16.0 mmol×L~(-1)时,过量供磷抑制了根系的生长,使平邑甜茶幼苗根系长度、表面积均大幅降低,根尖数量骤降。非损伤扫描离子选择电极测试表明,当生长介质磷浓度在3.0~6.0 mmol×L~(-1)时,平邑甜茶对NO_3~-有吸收作用,并在3.0 mmol×L~(-1)磷浓度时其吸收速率最高。而在0~2 mmol×L~(-1)及8.0~16.0 mmol×L~(-1)磷浓度处理下,平邑甜茶对NO_3~-有外排作用。随供磷水平的增加,各器官从肥料中吸收分配到的~(15)N量对该器官全氮量的贡献率(Ndff)及植株氮素利用率呈现先升高后降低的趋势,4.0 mmol×L~(-1)磷浓度时植株氮素利用率最大,为42.24%,超过4.0 mmol×L~(-1)植株氮素利用率显著降低。适当充足的供磷刺激了幼苗根系生长,从而促进平邑甜茶对氮素的获取,过量的NO_3~-抑制了平邑甜茶根系的生长,同时叶片硝酸还原酶的活性受到抑制,因此其氮素吸收和利用效率较低。因此,磷浓度在3.0~4.0 mmol×L~(-1)时最有利于平邑甜茶幼苗的生长及氮素的吸收利用。     

荞麦淀粉的真菌淀粉酶酶解动力学研究

为掌握真菌α-淀粉酶对荞麦淀粉的酶解特性，该文研究了不同底物浓度、酶浓度、pH值及温度对水解反应速率的影响，运用米氏方程对水解动力学过程进行描述和拟合，用Lineweaver-Burk和Wilkinson统计法求解动力学参数。结果表明，真菌α-淀粉酶对荞麦淀粉的水解反应初期遵循一级反应规律，可用米氏方程对水解动力学过程进行描述和拟合，在酶浓度为0.5 U/mL、pH值5.5、温度为55℃时米氏常数K_m为5.470 mg/mL，最大反应速率V_m为1.587 mg/(mL·min)。确立的包括底物浓度、酶浓度、水解温度在内的荞麦淀粉酶水解动力学模型，在303.15～333.15 K的温度范围内适用。     

食用菌SJ-1漆酶酶学性质及降解黄曲霉毒素B_1的研究

为了进一步掌握高效降解黄曲霉毒素B_1的食用菌SJ-1的特性,考察了温度、pH以及金属离子对食用菌SJ-1漆酶酶活的影响,同时研究了该漆酶降解黄曲霉毒素B_1的降解曲线和降解方程。结果表明,食用菌SJ-1漆酶的最适反应温度为35℃,最适pH值为3.0。Cu~(2+)对该漆酶酶活有一定的激活作用,而Fe~(2+)、Ca~(2+)、Mg~(2+)、Na~+、K~+对其酶活都有较强的抑制作用。食用菌SJ-1漆酶降解黄曲霉毒素B_1的方程为y=-0.1712x~(2+)20.107x-76.587,其中x为反应时间,范围为0~48 h,y为黄曲霉毒素B_1降解量(ng),该方程在0~48 h内,能够推算出食用菌SJ-1漆酶降解黄曲霉毒素B_1的降解量。本研究结果为食用菌漆酶降解黄曲霉毒素的应用提供了理论指导和技术支持。     

北京山地不同阔叶林型下土壤脲酶动力学与热力学特征

采取北京山地黑桦林、刺槐林、板栗林、槲树林及山杨-白桦混交林5种阔叶林型下0～0.2m、0.2～0.4m、0.4～0.6m土层土壤,通过测定不同尿素浓度、培养时间及培养温度下酶促反应的放氨量,计算脲酶的各项动力学和热力学参数,探讨5种阔叶林型下土壤脲酶酶促反应特征。结果表明:各林型土壤脲酶酶促反应的动力学和热力学参数随温度升高和土壤深度增加而变化,反应过程中脲酶含量、酶-底物络合物形成难度、酶促反应速度以及形成过渡态络合物时参加反应的分子必须克服的势垒、所需的自由能、有序性等变化特征均有差异。不同林型下0～0.2m层土壤酶促反应的动力学和热力学特征表现不同,山杨-白桦混交林下土壤脲酶酶促反应表现出脲酶含量高、对底物的亲合力强,酶促反应需要克服的势垒较低、有序性增加最大和反应速度最快;板栗林下土壤表现出脲酶含量较低,对底物的亲合力最弱,需克服的能障最大,有序性增加幅度最小,酶促反应最慢;黑桦林、槲树林和刺槐林土壤酶促反应各项参数同上述林型变化不同。     

东方栓孔菌在染料脱色中的应用及其脱色条件的优化

本研究利用东方栓孔菌（Trametes orientalis）菌株Cui6300发酵所得的粗酶液,对刚果红、结晶紫、铬天青、亚甲基蓝和中性红5种染料进行了催化脱色试验,并对其中脱色效果较好的染料进行了脱色条件优化。结果表明：东方栓孔菌漆酶粗酶液对结晶紫有相对较好的脱色效果。添加2,2＇-连氮-双（3-乙基苯并噻唑-6-磺酸）（ABTS）的粗酶液对结晶紫的降解效果没有明显促进作用,因此后续试验中直接采用粗酶液。脱色条件优化结果为：最佳初始pH值6.0,最佳培养温度55℃,最佳接种量2.0%,最佳转速160r/min,最佳底物浓度160mg/L。在此条件下反应96h,脱色率可达98.45%。本试验说明东方栓孔菌在印染废水治理方面具有较好的应用前景,可以作为一种新型菌株应用于染料脱色。     

铁碳复合材料催化内电解技术处理模拟农村铅污染水体效果

为考察基于新型铁炭复合填料的催化内电解技术处理模拟农村铅污染水体的特性,该文采用单因素试验设计和八因素三水平(考虑交互作用)正交试验设计,研究了初始pH值(1.0~8.0)、反应时间(10~90 min)和曝气量(0~12 L/h)对Pb~(2+)去除效果的影响。结果表明:初始pH值从1.0升高到8.0,铅(Pb~(2+))去除率先缓慢上升后急剧降低;反应时间从10 min提高到60 min,Pb~(2+)去除率稳步上升,继续延长至90 min,去除率趋于稳定;曝气量从0增大到12 L/h,Pb2+去除率先快速增加后缓慢降低;3个因素对Pb~(2+)去除效果的显著影响大小依次为:曝气量初始p H反应时间,最佳反应条件是:初始p H值3.0、反应时间60 min、曝气量6 L/h。按照一级动力学模型对反应阶段进行拟合,采用电子扫描显微镜(scanning electron microscope,SEM)观察了反应前后铁炭填料表面形态和结构变化,并利用X射线衍射(X-ray diffraction,XRD)分析了反应后溶液组分,推断得出催化内电解去除铅的机理是氧化还原和化学沉淀。当初始Pb~(2+)浓度为1.0 mg/L,在最佳试验条件下,处理后Pb~(2+)浓度降至0.037 mg/L,满足《地表水环境质量标准》(GB 3838-2002)Ⅲ类水体限值要求。研究结果可为农村铅污染水体修复提供理论和设计依据。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.