Effect of zinc levels on phosphorous and zinc content in sand‐cultured soybeans

Soybeans (Glvcine max L.) cv. “Clark”; were grown in the greenhouse in sand‐filled plastic pots sub‐irrigated with Hoagland No. 1 solution to determine the possible inhibitory effects of Zn on the uptake of P. Zinc rates used were 0.05 (control), 0.25, 0.5 and 2.5 ppm. Yields equalled the control at Zn levels of 0.25 and 0.5 ppm, but plants grown in solutions containing 2.5 ppm Zn were stunted severely. Foliar Zn and P levels differed very little among Zn treatments. Zinc levels were highest and P levels were lowest, however, in the roots and stems of soybeans grown in solutions of 2.5 ppm Zn. Zinc and P uptake was significantly inhibited in the leaves, stems and roots of plants grown at the highest Zn rate. The recycling of wastes containing high Zn content could adversely affect plant growth by a suspected antagonism with P.     

Sodium Alginate as an Adjuvant of an Antagonistic Bacterium, Pseudomonas fluorescens Strain A11RN, to Enhance Biocontrol of Turfgrass Snow Mold Caused by Typhula ishikariensis

Pretreatment with sodium alginate (20 g/m²) prior to application of a biocontrol agent, Pseudomonas fluorescens strain A11RN, enhanced the control turfgrass snow mold caused by Typhula ishikariensis biotype B. Disease severities in two fields relative to untreated control plots were 53% and 61% in plots treated with both the strain and sodium alginate, which were significantly lower than 69% and 77% in plots treated only with the strain. The antagonist population remained above the threshold for effective control (ca. 1×10⁷ cfu/cm³) at least for the first month under snow in pretreatment with sodium alginate. The population of the biocontrol agent after snowmelt on turfgrass was five times higher in sodium alginate-amended plots than in unamended plots. Sodium alginate alone did not reduce disease severity. Sodium alginate might have supported the survival of the applied strain. Received 7 June 1999/ Accepted in revised form 20 December 1999     

木霉菌对甜瓜枯萎病的防治

研究木霉菌T23、Ta22菌株对甜瓜枯萎病菌的拮抗作用和T23、Ta22二者复合处理对甜瓜枯萎病的室内及田间防治效果，结果表明：T23与Ta22对枯萎病菌拮抗系数都很高，二者复合处理对甜瓜枯萎病的田间相对防效可达79．00％。     

极端嗜热多肽的纯化、性质初探及对苗瘟的防效

本试验用加热法从多粘类芽孢杆菌(Paenibacillus polymyxa)LM-3菌株的发酵液中纯化得到2个极端嗜热多肽。平板拮抗实验表明,5μl纯化多肽对稻瘟病菌(Magnaporthe grisea)抑菌率达89.6%。SDS-PAGE电泳显示纯化多肽分子量介于6 000~7000 Da之间。多肽复性后,其中之一对稻瘟病菌表现出强的拮抗活性,命名为APPLM3(Antagonism Polypeptide fromPaenibacilluspolymyxaLM-3);另一个则无此活性,命名为PPLM3(Polypeptide fromPaenibacillus polymyxaLM-3)。APPLM3经氨基酸测序,获得了其N-末端5个氨基酸序列(H2N-ANDPR);以该序列为靶序列在NCBI上进行相似性检索,发现其可能与3个假设蛋白(或推导蛋白)相关。以APPLM3为主效成分配得5种微生物源生防乳剂,对水稻苗瘟进行了田间防效试验。试验结果表明,这5种乳剂的防效都优于LM-3拮抗液直接喷雾,其中AB4处理的防效最佳,达80.73%,其拮抗成分、吐温80、乳化剂OP、溶剂的质量比为50∶6.5∶1.75∶41.75。APPLM3为首次报道的兼具极端嗜热性和稻瘟病菌拮抗活性的小分子多肽。     

拮抗菌对香蕉枯萎病菌的抑菌作用初步研究

从土壤中分离到一株对香蕉枯萎病菌(Fusarium oxysporum f.sp.cubense)具有抑制作用的拮抗细菌--假单胞杆菌(Pseudomonas sp.),并对其抑菌效果、热稳定性以及作用机理进行了初步研究.结果表明,拮抗细菌发酵液及其无菌滤液对香蕉枯萎病菌的生长及其分生孢子的萌发具有显著的抑制作用(P＜0.05),并导致病菌菌丝和分生孢子芽管扭曲、膨大;拮抗细菌发酵液经121℃处理30min后,对病菌生长的抑制作用降低.     

深绿木霉紫外光诱导耐低温突变菌株的研究

通过紫外光诱变处理获得一种耐低温(10℃)的深绿木霉(Trichodermaaureoviride)突变菌株Tuv-1。该菌株在PDA培养基上连续转接培养5次,具有稳定遗传性。低温下与亲本菌株相比,Tuv-1菌丝生长速率大,对灰霉病菌的拮抗作用明显。     

香菇菌株亲缘关系的研究

以12个香菇菌株为材料进行了亲缘关系的研究.结果表明,以菌株的拮抗作用、酯酶同工酶和子实体氨基酸组成等综合鉴定菌株之间的亲缘关系是一种较为可靠的方法.12个菌株有不同的起源,其亲缘关系的远近与地理分布有明显的联系.同一类型菌株之间的差异是对不同生态环境长期适应、人工选择和杂交育种的结果.     

木霉（TR－5）对病原真菌的拮抗机制和防病效果研究

从土壤中分离获得一株木霉（Ｔｒｉｃｈｏｄｅｒｍａｓｐ．）菌株（ＴＲ－５），用对峙法和系列稀释法测定其对立枯丝核菌（Ｒｈｉｚｏｃｔｏｎｉａｓｏｌａｎｉ），禾谷丝核菌（Ｒｈｉｚｏｃｔｏｎｉａｃｅｒｅａｌｉｓ），西瓜枯萎病菌（Ｆｕｓａｒｉｕｍｏｘｙｓｐｏｒｕｍ∫ｎｉｖｅｕｍ），油菜菌核病菌（Ｓｃｌｅｒｏｔｉｎｉａｓｃｌｅｒｏｔｉｏｒｕｍ），昆明腐霉（Ｐｙｈｔｉｕｍｋｕｎｍｉｎｇｅｎｓ）和寄生疫霉（ＰｈｙｔｏｐｈｔｈｏｒａＰａｒａｓｉｔｉｃａ）的拮抗作问。结果表明，ＴＲ－５菌株对６种病原真菌都具有极强的拮抗作用，主要表现为缠绕、附着在病原真菌菌丝上，同时产生吸器侵入病原真菌的菌丝，使菌丝断裂。还能分泌有毒或抗生物质抑制其生长，并具有很强的生长竞争能力。ＴＲ－５菌株对立枯丝核菌，禾谷丝核菌和西瓜枯萎病菌的有效抑制浓度为１０６～１０７个孢子／ｍｌ；对油菜菌核病菌和昆明腐霉菌为１０４～１０５个孢子／ｍｌ；而对寄生疫霉为１０５～１０６个孢子／ｍｌ。用ＴＲ－５木霉的分生孢子制剂在温室条件下对黄瓜猝倒病（Ｐｙｔｈｉｕｍａｐｈａｎｉｄｅｒｍａｔｕｍ）和黄瓜疫病（Ｐｈｙｔｏｐｈｔｈｏｒａｄｒｅｃｈｓｌｅｒｉ）进行防治试验，效果分别     

香蕉枯萎病拮抗菌筛选试验

将从香蕉土壤中分离出的7个不同性状的芽孢杆菌菌株以及荧光假单孢菌、枯草芽孢杆菌、细黄链霉菌等分别用于测试对香蕉枯萎病生理小种4号的拮抗作用。结果表明,10个菌株中荧光假单孢菌表现出对香蕉枯萎病生理小种4号菌丝生长有良好、稳定的抑制作用;荧光假单孢菌和XP菌株混合后,其抑菌作用得到加强,抑菌效果最好。     

康氏木霉对立枯丝核菌7个融合群及3个亚群拮抗作用的研究

将从玉米纹枯病病斑上分离的3株康氏木霉(Trichoderma koningiiOud.),在琼脂玻片上与立枯丝核菌(Rhizoctonia solani Kuhn)7个菌丝融合群及3个亚群(AG-1-IA、AG-1-IB、AG-1-IC、AG-2-1、AG-2-2、AG-3、AG-4、AG-5、AG-6和 AG-BI)标准菌株对峙培养,观察其对丝核菌的拮抗作用.结果表明,3株木霉对各融合群的丝核菌均有强烈拮抗作用,融合群间及木霉菌株间的拮抗作用均无明显差异。其拮抗方式表现为缠绕、侵入,断裂菌丝,消解细胞质或使之变稀薄。