不同碳、氮源对甘蓝链格孢菌菌丝生长的影响

为探讨不同碳、氮源对甘蓝链格孢菌菌丝生长的影响,以从甘蓝品种W-14感病株上分离获得的菌种为供试材料,以该菌种在不同碳、氮源培养基上的菌落长势、直径、菌丝生长速率、生长指数、菌丝干重为测量指标,研究在基础培养基中添加13种常见氮源和6种常见碳源对甘蓝链格孢菌菌丝生长的作用,筛选出适宜该菌生长的营养物质。结果表明:在基础培养基中添加硝酸铵时,菌丝的生长速率及菌落直径较大,菌丝致密,其菌丝的生长指数最高为38.33,菌丝干重也较大;而在以淀粉为碳源的培养基上,菌丝的生长指数和菌丝干重最大,所以甘蓝链格孢菌菌丝生长的最佳氮源、碳源分别为硝酸铵和淀粉。     

防治小麦纹枯病菌和玉米茎基腐病菌的药剂筛选及复配增效评价

采用生长速率法,测定不同杀菌剂对小麦纹枯病菌和玉米茎基腐菌的室内毒力。针对高效药剂,以孙云沛法评价各配比的增效作用。结果表明,己唑醇和咯菌腈对小麦纹枯病菌的室内毒力最高,EC₅₀值分别为0.094 mg/L和0.312 mg/L;咪鲜胺和己唑醇对玉米茎基腐病菌的室内毒力最高,EC₅₀值分别为0.088 mg/L和0.593 mg/L。己唑醇和咯菌腈按照不同比例复配对小麦纹枯病菌没有明显的增效作用。咪鲜胺和己唑醇按照1:5、1:2和1:1比例复配对玉米茎基腐病菌均表现出明显的增效效果,其中1:5配比的共毒系数为212.2,增效作用最为显著,生产上可考虑用于上述病害防治。     

不同培养基对小麦纹枯病菌生长繁殖及致病力的影响

采用不同的培养基培养小麦纹枯病病菌,结果表明:在改良的PDA培养基、PDA培养基+小麦叶汁培养基、V8培养基和番茄培养基上培养的病原菌比在其他的培养基上培养的病菌菌丝生长速度快,且其对3种小麦品种的致病力较其他培养基上的病菌强,因此可用这四种培养基复壮、保存小麦纹枯病病菌。     

有机酸和氨基酸对双孢蘑菇菌丝生长的影响

本实验利用固体平板和液体摇瓶培养的方法,研究了柠檬酸、酒石酸、琥珀酸三种有机酸和丙氨酸、酪氨酸、精氨酸三种氨基酸在不同浓度下对双孢蘑菇菌丝生长的影响。通过测定各处理组的菌丝菌落直径、胞外蛋白含量、菌丝干重、胞内多糖、过氧化物酶活性和还原糖含量等生长参数,结果表明,外源加入0.04%的柠檬酸、琥珀酸、酒石酸和精氨酸能够促进双孢蘑菇的生长,其中琥珀酸组的菌丝干重最高,比对照组增加了131%;精氨酸组的胞外蛋白含量最高,比对照组增加了151%;柠檬酸组的胞内多糖含量和过氧化物酶活性的值最高,分别比对照增加了21%和146%。但过高浓度的有机酸和氨基酸,则抑制双孢蘑菇菌丝的生长。     

雪腐格氏霉侵染小麦的环境因素

室内试验表明，雪腐格氏霉侵染小麦的适宜温度为１７￣２０℃，２０℃以上有利于病菌在寄主组织中扩展。相对湿度在９３％以上２￣３天，病害就会普遍发生，持续时间越长，发病越严重。在２０℃及饱和湿度下，光照８０００￣１００００ｌｘ，每天光照６ｈ，最适于病菌侵入和扩展，长时间光照不利于病害发生。     

21种天然产物对小麦根腐病菌的抑菌活性

为探索小麦根腐病生防途径,筛选有效抑菌物质,达到农药减量的目的.以禾谷镰刀菌(Fusarium graminearum)、刺腐霉菌(Pythium spinosum)和小麦离蠕孢菌(Bipolaris sorokiniana)为供试材料,采用菌丝生长法测定了21种天然产物的抑菌活性.结果表明,反式细辛醚和顺式细辛醚对禾...     

雪腐捷氏霉中国菌系对小麦的致病性研究

研究了采自中国的新疆、陕西、青海、宁夏、四川、贵州、湖北等７省和捷克共１２个雪腐捷氏霉菌系对小麦的致病性和症状特点。各菌系对小麦的各部位均有奶强的致病性,但对穗部的致病性较弱。原采自红色雪腐病病株和成株雪霉叶桔病的两类菌系引起相同的症状。参试菌系间致病性强弱有明显差异,但同一菌系在小麦不同生育期对不同器官致病性的强弱相一致。     

不同条件对木霉菌菌丝生长的影响

木霉菌BTW5（T.longibrachiatum)和BTW41（T.atroviride)菌丝生长的最适温度是25－30℃，光照有利于木霉菌株菌丝的扩展。不同碳源、氮源对木霉菌菌丝生长的影响差异显著。BTW5菌丝生长的最佳碳源是麦芽糖，最佳氮源是蛋白胨；BTW41菌丝生长的最佳碳源是葡萄糖，最佳碳源是甘氨酸。     

作物根茬对土壤肥力及小麦产量的影响

本项研究讨论了作物根茬留地对土壤肥力及小麦产量的影响，试验结果表明，根茬留地可增加土壤有机质的含量、改善土壤物理性状、促进土壤酶转化、提高土壤HA／FA比值，使根茬留地比根茬刨除的小麦产量增加了3.6%-28.5%。     

茭白胡麻斑病菌生物学特性研究

对茭白胡麻斑病生物学特性进行了研究,结果表明：该菌菌丝生长的适宜温度10~35℃,最适温度25℃;分生孢子产生的适宜温度10~30℃,最适温度25℃;分生孢子致死温度为56℃;该菌菌丝生长和分生孢子产生的pH值3~12,最适pH值6~9,中性偏碱的条件下有利于分生孢子的形成;该菌菌丝生长最适碳源为乳糖,而产孢最适碳源为果糖;氮源酵母膏促进菌丝生长,酵母膏和氯化铵能促进产孢,牛肉膏和硝酸钾不利于产孢。     

Helminthosporium leaf blight resistance and agronomic performance of wheat genotypes across warm regions of South Asia

Helminthosporium leaf blight (HLB) is the most important disease constraint to wheat (Triticum aestivum L.) cultivation in the eastern Gangetic Plains of South Asia. A Helminthosporium Monitoring Nursery (HMN) including potential adapted and exotic sources of HLB resistance was developed in Bangladesh, India and Nepal to assess the stability of genetic resistance across locations. The 8th, 9th and 10th HMN assessed the HLB resistance and agronomic traits of 17 wheat genotypes across 20 environments of Bangladesh, India and Nepal in the 1999‐2000, 2000‐2001 and 2001‐2002 cropping seasons, respectively. The area under the disease progress curve (AUDPC) for HLB, grain yield, thousand‐kernel weight (TKW), days to heading, days to maturity, and plant height were examined. The 17 genotypes showed a range of variability for disease and agronomic characters. Disease severity (AUDPC) differed in the 3 years and showed the highest values in 2002. The increase in AUDPC in 2002 caused the lowest grain yield, with an average 18% reduction due to HLB. A few genotypes (SW 89‐5422, Yangmai‐6 and Ning 8201) appeared to have stable HLB resistance across environments. However, most of the higher‐yielding genotypes, except BL 1883, were unstable. The results suggest that careful selection of HLB resistance with acceptable grain yield, TKW and plant height may be possible using the wheat genotypes included in the HMN.     

Effect of Drechslera (Helminthosporium) sacchari Toxin upon the Permeability of Sugarcane Leaf and Callus Tissues

Sugarcane leaves and calli from highly susceptible and resistant varieties to eyespot disease were used to evaluate the Drechslera sacchari toxin effect at different concentrations and incubation times by measuring electrolyte leakage. This expression of disease resistance was observed not only in the leaf but also in the callus. Furthermore, the growth of resistant calli MS medium supplemented with DS toxin, was higher when compared to the susceptible ones. The possibility of obtaining resistant somaclones is confirmed.     

Resistance to Helminthosporium leaf blight and agronomic performance of spring wheat genotypes of diverse origins

Helminthosporium leaf blight (HLB), caused by a complex of Cochliobolus sativus (Ito & Kurib.) Drechsler ex Dastur and Pyrenophora tritici-repentis Died, is a serious disease of wheat (Triticum aestivum L.) in the warm lowlands of South Asia. Wheat cultivars grown in the area are either susceptible to HLB or possess low levels of resistance to it. A replicated field study was conducted in 1999 and 2000 at two sites in Nepal to determine the level of HLB resistance and other desirable traits in 60 wheat genotypes of diverse origin. The test genotypes were planted in main strips divided into two strips one of which was sprayed four times with Tilt (a.i. propiconazole) @ 125 g of a.i. ha^–1. Four readings of HLB were recorded to calculate the area under the disease progress curve (AUDPC). Other traits under investigation included biomass yield (BY), grain yield (GY), 1000-kernel weight (TKW), harvest index (HI), days to heading (DH) and maturity (DM), plant height (PHT), and effective tiller number (ETN). Wheat genotypes differed significantly for all traits. Mean AUDPC values ranged from 45 to 1268. A few exotic genotypes were highly resistant to HLB. Losses in GY due to HLB ranged from 2 to 26%, and TKW was reduced by up to 33%. A few genotypes showed HLB tolerance, i.e., relatively smaller GY and TKW reductions despite high levels of HLB. In general, medium to late maturity and higher levels of HLB resistance and low to high GY and TKW characterized genotypes exotic to South Asia. Biplot analysis identified several genotypes that were HLB-resistant and agronomically superior. Results suggest it is possible to improve HLB resistance of local wheat cultivars based on selective breeding using this pool of germplasm.     

骆驼蓬提取物对小麦玉米种子萌发及幼苗生长的影响

用乙醇和氯仿从骆驼蓬生长期的地上部分,提取出的醇溶物,脂溶物及水溶物,分别对小麦、玉米进行浸泡处理后,以种子萌发率和幼苗的植物生长量为指标,测定各提取物的生物活性,结果是：凡经处理的作物种子,其幼苗的生长率均有不同程度的提高。其中,小麦的生长率是醇溶物和水溶物处理最为显著,前者可使根系的生长率达91.03%,叶片达23.02%。后者可使根系生长率达68.99%,叶片达17.04%;而玉米的生长率是脂溶物和醇溶物处理最为显著,前者根系的生长率达35.36%,叶片达28.48%,后者根系达27.94%,叶片达30.88%。 处理对种子萌发的影响是与处理液的化学性质,浓度以及萌发的时间相关,醇溶物对种子萌发的抑制作用明显比水溶物和脂溶物强;低浓度的脂溶物和水溶物对种子萌发不显示抑制作用,高浓度的各提取物表现出不同程度的抑制作用,但随萌发时间的延长,即不再表现抑制作用。     

环境因素对藻类生长竞争的影响

为了研究环境因素对藻类生长竞争的影响,综述了国内外近几年的相关研究,发现大多为单因素对藻类生长的影响,而多因素对藻类生长的交互作用以及不同藻种间的竞争研究还存在不足。笔者简要介绍了藻类的分类及其在生态系统中的作用,详述了温度、光照、氮磷、pH对藻类生长竞争的影响,并在此基础上提出尚需重点研究的关键问题,以期深入了解环境因素对藻类生长竞争的影响,并为开展通过调控重要环境因素来改善藻类群落结构和水体生态环境、提高水体初级生产力等方面的研究提供可资借鉴的资料。     

植物根际促生菌对大蒜的促生、抗病作用研究

为了研究不同剂量的植物根际促生菌(PGPR)对大蒜生长时期的促生和抗病作用,以盆栽种植的大蒜种子为试材,用计数法计算其发芽率和常规测量法测定其株高;再用土壤温湿度检测仪测定种植所用土壤养分含量。与CK组相比,实验组B（施用4 g菌肥）铵态氮提高117.60%,有效钾提高593.15%,实验组C（施用6 g菌肥）速效磷提高238.77%;而实验组C的大蒜的发芽率提高15.17%,幼苗株高提高20%,叶绿素含量提高11.04% (P<0.05),这说明了PGPR对大蒜生长有促进作用。大蒜根腐病菌与植物根际促生菌的拮抗试验结果表明在30℃暗培养下,菌肥浓度为10^-2时有害微生物指数下降25%,表明其抑菌效果显著。本研究结果表明PGPR对大蒜促生作用显著,同时具有一定抗病效果,在农业发展中具有潜在的经济价值。     

影响RAPD实验结果的稳定性和可靠性因素研究

以小麦栽培种京411为材料，对小麦的基因组DNA进行PAPD分析,获得稳定而清晰的PCR扩增效果。对影响RAPD实验结果稳定性和可靠性的因素进行了初步探讨。     

烯效唑对小麦苗期生长的调控作用

试验结果表明，小麦播前种子处理（拌种，闷种或浸种），对小麦苗期生长的生物学效应，一是降低麦苗生长速度，控制苗高；二是促进麦苗分蘖，增加年前分蘖数，此外，还可提高叶片叶绿素含量及光合效率，降低地上部呼吸强度，增加干物质积累，提高麦苗素与抗寒性，收到增穗增产的效果。