野生桑黄菌种分离与培养特性研究初报

以新鲜野生桑黄子实体为材料,采用组织分离法获得纯菌株。该菌株的培养特性研究结果表明,桑黄菌丝生长的最适温度为28℃,最适pH为6.5,最适碳源是葡萄糖,最适氮源是蛋白胨,最适栽培培养基是鲜桑树枝木段培养基。     

珍稀植物青檀的生物学特性及栽培技术

青檀(Pterocektis tatarinowiiMaxim)是我国特有的纤维树种,已被列为国家三级保护植物。主要介绍了其生物学特性以及栽培技术,以期为该种植物的合理开发利用提供科学依据。     

苹果树枝干病害的生物防治研究

从苹果树体上分离得到颉颃菌株AT970 6。室内测定Valsamali等 3种枝干病害的病原抑制作用均为 10 0 %。田间采用AT970 6制剂对腐烂病和枝干轮纹病的防治效果分别为 99 5%和 86 0 %。     

Effects of soil moisture and sowing depth on the development of bean plants grown in sterile soil infested by <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> and <Emphasis Type="Italic">Trichoderma harzianum</Emphasis>

The effects of soil moisture (varying from 15% to 42% (v/v)) and sowing depth (1.5–6.0 cm) on the development of bean plants grown in sterile soil infested by the pathogen Rhizoctonia solani and its antagonist Trichoderma harzianum were studied under greenhouse conditions. The four possible combinations of soil infestation with both fungi were tested. Disease severity, percentage of plants emerged, plant height and dry weight were evaluated 3 weeks after sowing. Emergence rate and growth of plants inoculated only with R. solani were not affected by soil moisture, but in the presence of both fungi, plant emergence, plant height and dry weight significantly decreased when soil moisture diminished. Deep sowing significantly reduced the emergence rate and growth of those plants that were inoculated with R. solani only. However, when the soil was infested with both fungi, the effect of sowing depth was not significant. At a sowing depth of 6.0 cm, the percentage of plants emerged was 50% in the presence of T. harzianum, but only 6.7% when the pathogen was inoculated alone. The antagonist protected bean seedlings from pre-emergence damping-off, reduced disease severity and increased plant growth in the presence of R. solani, especially in moist soil.     

苦参生物碱对植物病原菌的离体抗菌活性研究

测定了苦参总碱(混和生物碱)及其单体苦参碱、氧化苦参碱、槐果碱、槐定碱、野靛碱等6个样品对11种植物病原真菌和3种细菌的离体抗菌活性。结果表明,在药剂浓度为500mg/L时,仅苦参总碱对黄瓜疫霉病和辣椒炭疽病菌、槐定碱对黄瓜疫霉病菌表现出较好的活性,菌丝生长抑制率分别为96.18%、54.90%、93.62%,苦参总碱和槐定碱对黄瓜疫霉病菌菌的EC50分别为178.21mg/L和162.13mg/L;6个样品对3种病原细菌的活性较低,在药剂浓度为100μg/mL时,生长抑制率均在20%以下。     

Note: Flight capacity,parasitism and emergence of five<Emphasis Type="Italic">Trichogramma</Emphasis> (Hymenoptera: Trichogrammatidae) species from forest areas in Brazil

The flight and parasitism capacities and emergence rate of fiveTrichogramma species [T. acacioi (Brun),T. bruni (Nagaraja),T. demoraesi (Nagaraja),T. maxacalii (Voegelé & Pointel) andT. soaresi (Nagaraja)] were compared. The flight capacity of these parasitoids was assessed in test units. A tube was placed inside each test unit with a piece of card with 300Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs parasitized by one of theTrichogramma species. The emerged adults inside the test units were classified according to their position as flyers, non-flyers and walkers. Cards withA. kuehniella eggs, parasitized by one of theTrichogramma species, were assessed to determine the parasitism rate and emergence of these natural enemies. The data were submitted to analysis of variance and the means compared by the Scott-Knott test at 5% probability.Trichogramma maxacalii exhibited better flight capacity than the other species, in addition to good parasitism rate and high percentage of emergence. http://www.phytoparasitica.org posting May 10, 2007.     

Biological control of pythium root rot of chrysanthemum in small-scale hydroponic units

The capacity of several strains of root-colonizing bacteria to suppressPythium aphanidermatum, Pythium dissotocum and root rot was investigated in chrysanthemums grown in single-plant hydroponic units containing an aerated nutrient solution. The strains were applied in the nutrient solution at a final density of 10⁴ CFU ml⁻¹ and 14 days later the root systems were inoculated withPythium by immersion in suspensions of 10⁴ zoospores ml⁻¹ solution. Controls received no bacteria, noPythium, or one of thePythium spp. but no bacteria. Strain effectiveness was estimated based on percent roots colonized byPythium and area under disease progress curves (AUDPC). In plants treated respectively withPseudomonas (Ps.)chlororaphis 63-28 andBacillus cereus HY06 and inoculated withP. aphanidermatum, root colonization by the pathogen was 83% and 72% lower than in the pathogen control, and AUDPC values were reduced by 61% and 65%. ForP. dissotocum, the respective strains reduced root colonization by 87% and 91%, and AUDPC values by 70% and 90%. In plants treated respectively withPs. chlororaphis Tx-1 andComamonas acidovorans C-4-7-28, root colonization byP. aphanidermatum was 84% and 80% lower than in the controls and AUDPC values were reduced by 66% and 57%; these strains did not suppressP. dissotocum. Burkholderia gladioli C-2-74 andC. acidovorans OCR-7-8-38, respectively, suppressed colonization of roots byP. dissotocum by 74% and 86%, and reduced AUDPC values by 60% and 70%, but were ineffective againstP. aphanidermatum. C. acidovorans OCR-7-8-39 reduced colonization and AUDPC values ofP. aphanidermatum by 57% and 42%, respectively.Pseudomonas corrugata 13,Ps. fluorescens 15 and JZ12, and three additional strains ofC. acidovorans were weakly or nonsuppressive againstP. aphanidermatum. Strains that reduced AUDPC values forP. aphanidermatum orP. dissotocum when applied at 10⁴ CFU ml⁻¹ were 11%–39% less effective at 10³ CFU ml⁻¹. Four tested strains (Ps. chlororaphis 63-28,Ps. chlororaphis Tx-1,B. cereus HY06, andB. gladioli C-7-24) in most instances suppressed root colonization and lowered AUDPC values ofP. aphanidermatum when applied at 14, 7 or 0 days before inoculation, but reduction of the respective variables was generally greater when the strains were applied at 14 days (63%–87% and 75%–78%) or 7 days (44%–47% and 31%–88%) than at 0 days (14%–31% and 23%–62%) before inoculation.Ps. chlororaphis Tx-1,Ps. chlororaphis 63-28 andB. cereus HY06 significantly suppressedP. aphanidermatum whether the temperature of the nutrient solution was high (32°C) or moderate (24°C). Taken together, the observations suggest thatPs. chlororaphis 63-28,B. cereus HY06,Ps. chlororaphis Tx-1,B. gladioli C-2-74 andC. acidovorans OCR-7-8-38 have the potential for controlling Pythium root rot in hydroponic chrysanthemums. http://www.phytoparasitica.org posting Jan. 24, 2007.     

Use of sclerotia of<Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis> for efficient production of conidia of<Emphasis Type="Italic">Coniothyrium minitans</Emphasis> in liquid culture

A study was conducted to determine the feasibility of using sclerotia ofSclerotinia sclerotiorum for producing conidia ofConiothyrium minitans in liquid culture. The medium (SST) was made of water containing 2.0, 1.5, 1.0 or 0.5% (w/v) ground sclerotia ofS. sclerotiorum and 100 μgl ⁻¹ thiamine hydrochloride (HCl). One ml of conidial suspension (2 × 10⁷ conidia ml⁻¹) ofC. minitans LRC 2534 was inoculated into 100 ml of SST medium or control (thiamine HCl in water) and incubated at 20 ± 2°C on a shaker at 200 rpm. Subsamples were removed periodically and examined under a compound microscope. Conidia in the SST media germinated within 24 h, developed into branched hyphae within 48 h, produced pycnidia after 3–4 days, and the pycnidia released mature conidia after 7 days. Production of conidia varied with the concentration of sclerotia in the SST medium. It was lower (3.6 × 10⁶ conidia ml⁻¹) at 0.5% but higher (1.2 × 10⁸ conidia ml⁻¹) at 2%. The new conidia were viable and the colonies developing from them showed the original morphological characteristics. It was concluded that using SST liquid medium as a substrate for mass production of conidia ofC. minitans has potential for use in commercial development of this mycoparasite as a biocontrol product. http:www.phytoparasitica.org posting Jan. 23, 2007.     

Effects of historical and present fragmentation on plant species diversity in semi-natural grasslands in Swedish rural landscapes

Habitat loss and fragmentation of natural and semi-natural habitats are considered as major threats to plant species richness. Recently several studies have pinpointed the need to analyse past landscape patterns to understand effects of fragmentation, as the response to landscape change may be slow in many organisms, plants in particular. We compared species richness in continuously grazed and abandoned grasslands in different commonplace rural landscapes in Sweden, and analysed effects of isolation and area in three time-steps (100 and 50 years ago and today). Old cadastral maps and aerial photographs were used to analyse past and present landscape patterns in 25 sites. Two plant diversity measures were investigated; total species richness and species density. During the last 100 years grassland area and connectivity have been reduced by about 90%. Present-day habitat area was positively related to total species richness in both habitats. There was also a relationship to habitat area 50 years ago for continuously grazed grasslands. Only present management was related to species density: continuously grazed grasslands had the highest species density. There were no relationships between grassland connectivity, present or past, and any diversity measure. We conclude that landscape history is not directly important for present-day plant diversity patterns in ordinary landscapes, although past grassland management is a prerequisite for the grassland habitats that can be found there today. It is important that studies are conducted, not only in very diverse landscapes, but also in managed landscapes in order to assess the effects of fragmentation on species.     

The need for biological realism in habitat modeling: a reinterpretation of Zharikov et al. (2006)

Zharikov et al. (2006: Landscape Ecology 21:107–120) modeled the nest-site habitat use of marbled murrelets (Brachyramphus marmoratus) in Desolation Sound (DS) and Clayoquot Sound (CS), British Columbia. They compared known nest sites, located with radio-telemetry, with randomly-located points within the same areas. Their conclusions suggest that murrelets tended to nest in disproportionately smaller fragments within the more disturbed DS landscape; streams, steeper slopes, and lower elevations were selected in both landscapes; murrelets nested closer to recent clearcuts than would be expected in the DS landscape; and survivorship of nestlings was greater in areas with recent clearcuts and was positively correlated with recent habitat fragmentation. These conclusions are contrary to current management guidelines in British Columbia, and therefore require close scrutiny. Our detailed examination reveals flaws in their use of data, application of modeling, and most seriously, interpretation of the results. Problems include: conceptual errors in the interpretation of models; inappropriate spatial resolution; confusing use and interpretation of fragmentation and patch size data; overemphasis of statistically significant but biologically trivial results; and ignoring some contradictory studies. We conclude that it would be risky to apply the results from Zharikov et al. in the selection of murrelet nesting habitat for management purposes in British Columbia. Our review identifies issues that may arise in other ecological modeling studies and stresses the need for biological realism in addition to statistical rigour.