不同种类真菌多糖对小麦黄矮病的防治效果

为了筛选小麦黄矮病的真菌多糖防治药剂及其适宜浓度,将云芝、灵芝、虫草等13种真菌多糖稀释成0.1、0.5、1.0、2.0g·L-1溶液,以清水为对照,比较分析了叶面喷施真菌多糖对小麦黄矮病的预防和治疗效果,同时对防效好的1.1%云芝葡聚糖(多糖)与常规植物抗病毒药剂的田间防效进行了比较。结果表明,13种真菌多糖对小麦黄矮病的预防作用都显著高于治疗作用,且真菌多糖间和浓度间差异均显著,其中云芝多糖1.0g·L-1、云芝多糖2.0g·L-1、蜜环菌多糖2.0g·L-1、灰树花多糖2.0g·L-1、猪苓多糖2.0g·L-1的预防效果分别为86.88%、86.58%、86.33%、86.04%和85.97%。1.1%云芝葡聚糖800倍液为适宜喷施浓度,其防效64.27%,保产22.70%,说明云芝多糖是一种有前途的新型小麦黄矮病免疫抑制剂。     

多效降温反季节菇田栽培食用菌效果对比试验

针对广东省漫长的高温季节进行了人工低能耗降温试验，采用超高压微量喷雾、山水沟灌、棚顶滴流、增设隔热层等多效降温措施，使大棚式菇田内外温差在高温天气下达到5～7℃，使杏鲍菇、香菇、猴头菇、秀珍菇等中低温型食用菌品种可以在夏季正常出菇。为非空调制冷条件下延长广东的食用菌生产季节提供了有效的方法，其低廉的能耗成本为农村的推广创造了条件。     

15种杀虫剂对3种虫生真菌孢子萌发的影响

选择了15种杀虫剂来测验布氏白僵菌、球孢白僵菌和绿僵菌孢子萌发的影响,结果表明,所有杀虫剂对真菌的分生孢子萌发均有不同程度的抑制作用,浓度愈高,抑制作用越大.总的来看,对球孢白僵菌影响最大,布氏白僵菌次之,绿僵菌影响最小.混配农药绿保1号对3种虫生真菌的影响最小,其次是乙酰甲胺磷和甲胺磷.另外,不同真菌对同一种杀虫剂的敏感性亦有较大差异.因此,在田间进行菌药混用防治害虫前,应进行严格的试验.     

药剂处理对重茬大棚草莓根际微生物的影响

在初果期、盛果期和采果末期3个时期,研究了3种处理(太阳能防治剂、无公害草莓重茬病防治剂、溴甲烷)对重茬大棚丰香草莓根际土壤微生物数量的影响,从根际土壤中分离筛选得到14个纯菌株并做了初步的菌属鉴定,试验结果表明:药剂处理后的土壤比对照真菌、放线菌数量减少,细菌数量增多,真菌与细菌的比值显著降低,并与果实产量有显著相关性;线虫数量的变化趋势为初果期多,盛果期、采果末期逐渐减少。     

稻田套种食用菌高产配套技术研究

研究了稻田套种食用菌的高产模式及配套技术。其核心是:(1)选择适宜水稻品种粤优938、Ⅱ优838、65002等和适宜食用菌品种平菇、毛木耳、茶薪菇等;(2)水稻合理密植28cm×20cm,适宜套种量9万袋/hm2;(3)水分管理采取湿栽护苗,沟水育穗,垄畦沟灌技术;(4)病虫害防治以农业防治为基础、生物防治为主、化学防治为辅。为实现高产高效提供技术保障。     

不同土壤添加剂对番茄苗期土壤根际微生物数量的影响

将8种物质苜蓿汁、韭菜汁、木醋液、白菜汁、萝卜汁、葱汁、草木灰和蘑菇汁分别与有机肥以1:7的比例混合,制成土壤添加剂,然后再将配好的不同土壤添加剂分别按1:30的比例加入到土壤中,混合均匀,种植上番茄,设有机肥处理作为对照,待番茄苗出土后,每隔7d测定一次番茄土壤根际微生物数量(主要测定土壤细菌,土壤真菌和土壤放线菌的数量)。测定结果表明,在整个测定期间,与有机肥对照相比,苜蓿汁与有机肥、韭菜汁与有机肥和木醋液与有机肥配制的土壤添加剂对土壤中微生物数量都有增加趋势。木醋液与有机肥配制的土壤添加剂在加入土壤15d,土壤细菌、土壤放线菌和土壤真菌数量就增加到最大,分别为1131.94%、191.67%和348.19%。     

外生菌根真菌纯培养中生理活性物质代谢的研究

随着外生菌根研究的不断深入,越来越多的菌根工作者开始注意到了外生菌根真菌生理活性物质研究的重要价值。T.Santoro et al.,G.N.Krywolap et al.,D.H Marx等先后研究了外生菌根菌在各种培养条件下产生拮抗活性物质及这些拮抗物的理化性质和生物学功能,证明了外生菌根具有生物防治效应的部分原因是由于真菌抗生素的分泌。80年代以来,发现外生菌根及其真菌产生的植物激素在形成菌根及促进寄主植物生长方面起重要作用。如J.H.Graham et al.等先后研究了外生菌根菌产生某些     

Fungal/bacterial ratios in grasslands with contrasting nitrogen management

It is frequently hypothesised that high soil fungal/bacterial ratios are indicative for more sustainable agricultural systems. Increased F/B ratios have been reported in extensively managed grasslands. To determine the shifts in fungal/bacterial biomass ratio as influenced by grassland management and to find relations with nitrogen leaching potential, we sampled a two-year-old field experiment at an organic experimental farm in the eastern part of The Netherlands. The effect of crop (grass and grass-clover), N application rate (0, 40, 80, ) and manure type (no manure, farm yard manure and slurry) on the F/B ratio within three growing seasons was tested, as well as relations with soil and crop characteristics, nitrate leaching and partial N balance. Biomass of fungi and bacteria was calculated after direct counts using epifluorescence microscopy. Fungal and bacterial biomass and the F/B ratio were higher in grass than in grass-clover. The F/B ratio decreased with increasing N application rate and multiple regression analysis revealed a negative relationship with pH. Bacterial activity (measured as incorporation of [³H]thymidine and [¹⁴C]leucine into bacterial DNA and proteins) showed the exact opposite: an increase with N application rate and pH. Leaching increased with N application rate and was higher in grass-clover than in grass. Partial N balance was more positive at a higher N application rate and showed an inverse relationship with fungal biomass and F/B ratio. We conclude that the fungal/bacterial biomass ratio quickly responded to changes in management. Grasslands with higher N input showed lower F/B ratios. Grass-clover had a smaller fungal biomass and higher N leaching than grass. In general, a higher fungal biomass indicated a lower nitrogen leaching and a more negative partial N balance (or smaller N surplus), but more observations are needed to confirm the relationship between F/B ratio and sustainability.     

Fungal colonization as affected by litter depth and decomposition stage of needle litter

The present study was designated to evaluate the relative effects of litter depth and decomposition stage of needles on fungal colonization of needle litter in field experiments. The experiment was carried out in coniferous temperate forests in central Japan. Needle litter of Chamaecyparis obtusa and Pinus pentaphylla var. himekomatsu at two decomposition stages (recently dead and partly decomposed) were placed into the organic layer at two depths (on the surface of and beneath the litter layer). Fungal colonization of needles after 1 year was examined in terms of hyphal abundance and frequency of fungal species. Total and live hyphal length on needles were affected by the litter depth and (or) the decomposition stage of needles. Length of darkly pigmented hyphae on needles was 1.7-2.6 times greater beneath the litter layer than on the litter surface regardless of the decomposition stage of needles. Length of clamp-bearing hyphae in Pinus pentaphylla was 5.0-5.2 times greater in partly decomposed needles than in recently dead needles regardless of the litter depth. Frequencies of Pestalotiopsis spp. and Cladosporium cladosporioides were higher on recently dead needles than on partly decomposed needles and (or) were higher on the litter surface than beneath the litter layer. Frequencies of Trichoderma, Penicillium, and Umbelopsis species generally were higher on partly decomposed needles than on recently dead needles and were higher beneath the litter layer than on the surface.     

Effects of silver nanoparticles on soil microorganisms and maize biomass are linked in the rhizosphere

Silver nanoparticles hold great promise as effective anti-microbial compounds in a myriad of applications but may also pose a threat to non-target bacteria and fungi in the environment. Because microorganisms are involved in extensive interactions with many other organisms, these partner species are also prone to indirect negative effects from silver nanoparticles.Here, we focus on the effects of nanosilver exposure in the rhizosphere. Specifically, we evaluate the effect of 100 mg kg⁻¹ silver nanoparticles on maize plants, as well as on the bacteria and fungi in the plant's rhizosphere and the surrounding bulk soil. Maize biomass measurements, microbial community fingerprints, an indicator of microbial enzymatic activity, and carbon use diversity profiles are used. Hereby, it is shown that 100 mg kg⁻¹ silver nanoparticles in soil increases maize biomass, and that this effect coincides with significant alterations of the bacterial communities in the rhizosphere. The bacterial community in nanosilver exposed rhizosphere shows less enzymatic activity and significantly altered carbon use and community composition profiles. Fungal communities are less affected by silver nanoparticles, as their composition is only slightly modified by nanosilver exposure. In addition, the microbial changes noted in the rhizosphere were significantly different from those noted in the bulk soil, indicated by different nanosilver-induced alterations of carbon use and community composition profiles in bulk and rhizosphere soil.Overall, microorganisms in the rhizosphere seem to play an important role when evaluating the fate and effects of silver nanoparticle exposure in soil, and not only is the nanosilver response different for bacteria and fungi, but also for bulk and rhizosphere soil. Consequently, assessment of microbial populations should be considered an essential parameter when investigating the impacts of nanoparticle exposure.