西芹鲜根浸提液对黄瓜枯萎病菌化感作用机理的研究——鲜根浸提物处理后黄瓜枯萎病菌形态及孢子生长的变化

将西芹鲜根的不同浸提液(乙醇、丙酮、蒸馏水)按比例加入相应的培养基(PDA、水琼胶)中,接入黄瓜枯萎病病菌,观察浸提液处理后的黄瓜枯萎病病菌菌体形态结构、病菌孢子数量及萌发率的变化,以研究浸提物对黄瓜枯萎病菌的化感作用机理。实验结果表明:西芹鲜根的不同浸提液(丙酮、乙醇和蒸馏水)都使黄瓜枯萎病菌菌丝的生长受到抑制,病菌孢子数量减少,孢子萌发率降低。其中丙酮浸提液的抑制效果最好,其次是乙醇浸提液,最后是蒸馏水浸提液。

不同水分处理对高山羊齿孢子生长的影响

探讨不同水分处理对高山羊齿孢子生长的影响。按照土壤水分含量比例设置4个水分处理,分别为80%~70%（W1）、60%~50%（W2）、40%~30%（W3）、20%~l0%（W4）,研究其对高山羊齿孢子生长的影响。结果表明：4种水分处理中,随着水分的不断减少,高山羊齿叶片叶长、叶宽、单枝叶面积、单枝叶面积增长量及新增叶片数也随之减少;叶片的颜色随着水分的减少而变淡,由浓绿变为淡绿。W2处理下,叶片质地佳,生长势好,产孢率低,综合考量,水分处理W2较好。

Inhibition of Chlamydospore Germination and Mycelial Growth of Trichoderma spp. by Chemical Fungicides

For exploring the influences of application and residue of chemical fungi- cides on chlamydospore preparations of Trichoderma spp., the effects of seven chemical fungicides on chlamydospore germination and mycelia growth of two bio- control fungi T. harzianum 610 and T. Iongibrachiatum 758 were studied. Carben- dazim, tebuconazole and difenoconazole showed strong toxicities, thiram and car- bexin showed moderate toxicities, and metalaxyl showed Mycelia growth of the two strains was more sensitive to most tested fungicides than those of chlamydospore germination. Chlamydospore germination of 610 was more sensitive to tested fungicides than those of 758, and mycelia growth of 758 was more sensitive to most tested fungi- cides than those of 610. Among the seven fungicides, 98% carbendazim had the strongest effects （ECru values were 1.64 and 0.05μpg/ml）, and 70% pentachloroni- trobenzene had the weakest effects （EC50 values were 1.64 and 0,05 μg/ml） for chlamydospore germination and mycelia growth of 610. As for 758, 98% carbendaz- im had the strongest inhibitory effects and 95% metalaxyl had the weakest inhibitory for chlamydospore germination of 756 （EC50 values were 0.62 and 1 108.61 μg/ml respectively）, whereas 96.2% tebuconazole showed the strongest inhibitory effects for mycelia growth of 758 （EC= value was 0.32μg/ml）, and 95% metalaxyl was the weakest （EC= value was 1 206.29 μg/ml）. According to the applied concentration of different fungicides in practice, we concluded that chlamydospore preparations of 610 and 758 could not be combined with carbendazim, tebuconazole, thiram and carboxin for controlling plant diseases, and the pesticide residues to the biocontrol effects should be kept in mind. Chlamydospore preparations of 610 and 758 can be and difenoconazole for controlling plant dis- eases, 758 chlamydospore preparations and germinated chlamydospore of 610 can be combined with metalaxyl for controlling plant diseases, and pesticide residue risk was not serious.

Analysis of the Biological Characteristics of a Parasitical Fungus in Chrysosplenium absconditicapsulum J. T. Pan Leaves

[Objective] This study aimed to uncover the biological characteristics of a parasitical fungus in Chrysosp/enium absconditicapsu/um J. T. Pan leaves. [Method] PDA medium was used to isolate the fungus from C. absconditicapsulum leaves; PDA medium, modified KB medium and Czapek medium were adopted to cultivate the isolated strain. [Result] Colonies of the strain were stretched, white, fedora- shaped with smooth and wavy edges, and showed diameter growth on PDA medi- um, modified KB medium and Czapek medium. At the late stage of culture, the colonies turned into cyanish brown on the above media. Spores were black and born on the surface of colonies on PDA medium with blackened medium. While on modified KB medium and Czapek medium, they were born at the edge of colonies with blackened medium. The spores varied in a wide range of shapes, mostly ob- clavate, sometimes spherical or ellipsoidal. The conidia were muriformly septate with transverse or longitudinal or oblique septations. The pseudo-beaks were short and cylindrical. [Conclusion] According to relevant literatures, the isolated strain is a fungus in Alternaria, Dematiaceae, Hylohomycetales, Hyphomycetes, Deuteromycotina.

Early development of Costaria costata(C.Agardh) Saunders and cultivation trials

Costaria costata(C.Agardh) Saunders is one of common kelps distributed in many coastal areas worldwide;however,in China,no reports have been made on cultivation of the genus.To investigate potential cultivation of the species in the northern part of China,trials on isolation and preservation of the gametophytes were conducted using C.costata from Korea;growth and development of the gametophytes were observed.We showed that at 10±1°C,60 μmol m-2s-1 and 12:12 h(L:D),freshly released zoospores settled down within 1 hour,and then developed into the primary cell during the following 2 days.After a vegetative growth phase lasting 6-8 days,female gametophytes became 3-4 times larger in diameter than that of the primary cell,but still remained at a unicellular stage,while male gametophytes divided into 4-10 cells with only a slight change in size.Fertilization occurred within 10 days after the zoospores were released from the sporangia,and the apical and basal tissues of the juvenile sporophyte divided and differentiated into the blade and stipe.Temperature and irradiance influenced gametophytic vegetative growth and developmental patterns.Generally,low irradiance(15 μmol m-2s-1 and 30 μmol m-2s-1) was unfavorable to the induction of fertility,but it enhanced female gametophyte division.The optimal conditions for vegetative growth were 15°C and 30 μmol m-2s-1.After transplantation of the juvenile seedlings and after eight months cultivation,the harvested mature blade reached 194 cm in length and 32.7 cm in width.Our study proves that it is feasible to implement propagation and large scale cultivation of C.costata in northern China.

Controlling of Fusarium Wilt of Cucumber by Antagonistic Bacteria

Studying about the effect of four pseudomonas and two serratia isolates on growth of Fusarium oxysporum showed that, Pseudomonasfluorescens No.2 ＆ No.3 and Serratia marcescens No.2 gave highest inhibition zones which were 37.33, 35,00 and 31.33 mm, respectively. Evaluating about the effect ofpseudomonas and serratia culture filtrates at three concentrations （10, 25, 50%） on the linear growth and spore germination ofFusarium oxysporum revealed that, all filtrates of the tested isolates reduced the mycelial growth and spore germination of F. oxysporum. All filtrates of the tested isolates at 50% concentration completely inhabited spore germination ofF. oxysporurn. Culture filtrates of Pseudomonasputida and Serratia marcensens No.2 at 50% concentration reduced the mycelial growth of F. oxysporurn by 80.74 and 80.37% respectively. In this respect, all tested isolates made lysis to mycelial of F. oxysporum except Pseudornonasfluorescens No.3. Effect of treating cucumber seeds with cell suspension of pseudomonas and serratia isolates on incidence of Fusarium wilt disease revealed that all isolates were effective in reducing disease incidence and disease severity and increasing the percentage of healthy plants compared to the control. Pseudornonasfluorescens No.3 and Serratia marcensens No.2 were the best isolates and completely prevented the disease incidence.

Response of Soil Phosphorus Required for Maximum Growth of Asparagus officinalis L. to Inoculation of Arbuscular Mycorrhizal Fungi

Fertilizer application efficiently increases crop yield, but may result in phosphorus(P) accumulation in soil, which increases the risk of aquatic eutrophication. Arbuscular mycorrhizal fungi(AMF) inoculation is a potential method to enhance P uptake by plant and to reduce fertilizer input requirements. However, there has been limited research on how much P application could be reduced by AMF inoculation. In this study, a pot experiment growing asparagus(Asparagus officinalis L.) was designed to investigate the effects of AMF inoculation and six levels of soil Olsen-P(10.4, 17.1, 30.9, 40.0, 62.1, and 95.5 mg kg-1for P0, P1, P2, P3, P4 and P5treatments, respectively) on root colonization, soil spore density, and the growth and P uptake of asparagus. The highest root colonization and soil spore density were both obtained in the P1treatment(76% and 26.3 spores g-1soil, respectively). Mycorrhizal dependency significantly(P < 0.05) decreased with increasing soil Olsen-P. A significant correlation(P < 0.01) was observed between mycorrhizal P uptake and root colonization, indicating that AMF contributed to increased P uptake and subsequent plant growth.The quadratic equations of shoot dry weight and soil Olsen-P showed that AMF decreased the P concentration of soil required for maximum plant growth by 14.5% from 67.9 to 59.3 mg Olsen-P kg-1. Our results suggested that AMF improved P efficiency via increased P uptake and optimal growth by adding AMF to the suitable P fertilization.