白菜根肿病的接种方法

根肿病是由芸薹根肿菌Plasmodiophora brassicae Woronin引起的土传性病害.根肿菌属于专性寄生菌,不能直接培养,所以对带菌植株活体的研究尤为重要,而建立稳定的接种方法是带菌植株活体研究的基础.Asano等曾提出过浸醮法、插入法和菌土法等接种技术,但至今国内外对十字花科根肿病还没有统一且稳定的接种方法.为此,本试验对白菜根肿病的接种方法进行了研究.     

防治白菜根肿病的药剂筛选

分别采用拌药法和灌药法,比较了10种供试药剂对白菜根肿病的温室防治效果,并对盆栽试验防效较好的3种药剂进行了田间药效试验。结果表明,在温室条件下,50%氟啶胺悬浮剂(1 g/m3)、50%甲基硫菌灵可湿性粉剂(25 g/m3)、70%代森锰锌可湿性粉剂(35 g/m3)和40%五氯硝基苯粉剂(20 g/m3)的拌药处理,对白菜根肿病的防效均在50%以上,显著优于灌药处理的防效。田间药效试验结果表明,50%氟啶胺悬浮剂(2 g/m3)拌药处理的防效在80%以上,与盆栽药效试验结果一致,并显著优于其他药剂处理。     

Suppression of clubroot formation in Chinese cabbage by the root endophytic fungus, Heteroconium chaetospira

Root-colonizing fungi were isolated from a total of 663 root segments of Chinese cabbage plants grown in soils collected from wheat, rape, Chinese cabbage, and napier grass fields. Most of the 322 isolates were from the wheat field soil and comprised 18 genera and two septate fungal groups. Hyaline and dark septate fungi accounted for approximately half the isolates from the wheat field soil. Sixteen isolates almost completely suppressed clubroot in sterile soil. Amongst these 16 isolates, two from Heteroconium chaetospira were also effective in nonsterile soil. Chinese cabbage seedlings from seed treated with these two isolates appeared healthy, and inoculation with one isolate promoted growth. Hyphae of the fungus covered the root surface and extensively colonized the inner cortical tissues.     

Effect of crop rotation on the incidence of soil-borne fungal diseases of potato

Effects of crop rotation on the incidence of soil-borne pathogens and on the performance of potato were investigated in five field experiments. Rotations differed in cropping frequency of potato and in crop sequence.Incidence of stem canker caused byRhizoctonia solani was strongly influenced by the cropping frequency of potato and not by crops with which the potato was alternated in the rotation. Cropping frequency of potato also affected the occurrence of black scurf, but less pronounced than for stem canker. The antagonistVerticillium bigutatum slightly reducedR. solani (black scurf) in plots on sandy soil continuously cropped with potato. Incidence of stem canker was also strongly affected by granular nematicides applied to the soil, nitrogen level and the cultivar grown.Stem infections byVerticillium dahliae depended on the cropping frequency of potato, by the crop with which the potato was alternated in the rotation and by the density and virulence of endoparasitic nematodes, especiallyMeloidogyne spp.Crop rotation had no effect at all on incidence of common scab on tubers, whereas the effect of cropping frequency of potato on netted scab was highly significant. When cultivars were grown susceptible to both scab types, netted scab supressed common scab.     

Effect of crop rotation on the incidence of soil-borne fungal diseases of potato

Effects of crop rotation on the incidence of soil-borne pathogens and on the performance of potato were investigated in five field experiments. Rotations differed in cropping frequency of potato and in crop sequence.Incidence of stem canker caused byRhizoctonia solani was strongly influenced by the cropping frequency of potato and not by crops with which the potato was alternated in the rotation. Cropping frequency of potato also affected the occurrence of black scurf, but less pronounced than for stem canker. The antagonistVerticillium bigutatum slightly reducedR. solani (black scurf) in plots on sandy soil continuously cropped with potato. Incidence of stem canker was also strongly affected by granular nematicides applied to the soil, nitrogen level and the cultivar grown.     

Effect of crop rotation on Globodera rostochiensis and on potato yield1

A crop rotation field study was conducted in 1981–1989 to assess the effect of six crop rotation sequences on a soil population of potato cyst nematode (PCN), Globodera rostochiensis, and on potato yield. In the plots with potato monoculture, the tuber yield decreased from 35 to 4.6 t ha^?1. All other cropping systems maintained the yield at the original or an even higher level. In monoculture, the population density of the nematode was raised during the first 3 years from 0.1 to 265 larvae g^?1 soil, and the density fluctuated afterwards between 30 and 136 larvae g^?1 soil. Three of the cropping systems, (1) susceptible potato once in 5 years, (2) susceptible potato once in 4 years, and (3) potato once in 3 years using resistant (H1) and susceptible cultivars alternately, decreased the nematode density under the economic threshold or even under the level of detection. The nematicide treatments (oxamyl) did not control nematode multiplication but prevented yield losses. No nematicide is currently registered nor needed for the control of PCN in Finland. The nematode can be controlled effectively with crop rotation, resistant cultivars and early harvesting.     

Suppression of clubroot and Verticillium yellows in Chinese cabbage in the field by the root endophytic fungus, Heteroconium chaetospira

Chinese cabbage seedlings inoculated with an isolate of the hyphomycete, Heteroconium chaetospira, were transplanted to the field. After 3 months, they showed a 52–97% reduction in clubroot and a 49–67% reduction in Verticillium yellows compared with noninoculated controls. H. chaetospira colonized the cortical cells, especially in the root tip region. Infected plants showed no disease symptoms. The infection process involves the formation of appressoria on the cell surface and the subsequent growth of hyphae within cells. H. chaetospira colonized 18 plant species, indicating a wide range of hosts. It may have potential as a biocontrol agent for clubroot and Verticillium yellows.     

一株多黏类芽胞杆菌 Paenibacillus polymyxa 菌株P1防治广东菜心根肿病的研究

芸薹根肿病是一种危害极大的世界性病害。对此病害的防治多采用化学药剂,但过多地使用化学农药,不仅会导致病原菌的抗药性和药剂防效的不稳定,还会造成环境污染和食品安全等问题。筛选生防菌株并将其开发成有效的生物农药,是防治根肿病并保持绿色农业可持续发展的新途径。本研究选用了多种生防菌对芸薹根肿菌Plasmodiophora brassicae Woron.的休眠孢子进行拮抗测试,筛选出一株能抑制P.brassicae休眠孢子萌发的多黏类芽胞杆菌Paenibacillus polymyxa菌株P1。通过液体发酵和剂型处理,将P1制成悬浮剂(P1-SC),用于室内生测和大田试验,测定其对广东菜心根肿病的防治效果。盆栽试验结果表明,对菜心根肿病的防治效果与所使用的P1-SC浓度呈正相关,当施用P1-SC中P1的浓度≥1×10~6 cfu/mL时,对菜心根肿病的防治效果(83.0%)与化学农药氟啶胺(500 mg/L)的防治效果(100.0%)没有显著性差异,但显著高于(P≤0.05)一种商品枯草芽孢杆菌(2×10~7 cfu/mL)的防治效果(29.8%)。2018年的大田试验结果表明,P1-SC处...     

分蘖洋葱与番茄伴生根系分泌物对根结线虫的影响

为明确根系分泌物在番茄伴生分蘖洋葱Allium cepa var.agrogarum Don.体系中减轻番茄根结线虫病的作用,本研究以番茄L ycopersicon esculentum和分蘖洋葱为试材,通过双室试验及外源添加根系分泌物等方法,研究了根系分泌物对根结线虫死亡率、卵孵化率的影响以及根系分泌物对线虫的吸引率...     

Effect of tillage, cover crop and crop rotation on the composition of weed flora in a sandy soil

The development of integrated weed management strategies requires knowledge of mechanisms that influence compositional changes in weed flora. A 9-year study was initiated in 1988 at Delhi, Canada, on a loamy sand soil to evaluate the effect of tillage systems [conventional (CT) and no-till (NT)] and cover crops (only in NT) on weed density, species composition and associations, and crop yield in a winter wheat ( Triticum aestivum L.)/bean/winter wheat rotation. Three bean types: soyabean ( Glycine max L. Merr.), white bean ( Phaseolus vulgaris L.) and kidney bean ( P . vulgaris L.) were included. The NT system included variations: rye ( Secale cereale L.) or maize ( Zea mays L.) cover crop, volunteer wheat disked after harvest and wheat stubble. Data were collected in 1994, 1995 and 1996. Tillage systems, cover crops and crop type had differential effects on weed densities, species composition and associations. Weed densities were not affected by tillage or cover crops in wheat but, in the beans, densities were greater in the CT than in the NT systems. Various associations of weed species with tillage system, cover crop and crop type were observed. Crop yields were not affected by tillage type or cover crop, except that soyabean yields were highest in plots with cover crops.     

The role of siderophores in potato tuber yield increase by Pseudomonas putida in a short rotation of potato

The effect of treatment of potato seed tubers withPseudomonas putida isolate WCS358 on tuber yield was studied in different crop rotations at the Experimental Farm De Schreef, near Lelystad. With untreated, tuber yield in a 1:3 (short) rotation compared to yield in a 1:6 (long) rotation of potato was decreased by 11% at 86 days (seed tuber harvest) and by 14% at 130 days (ware potato harvest) after seeding. Seed tuber treatment with the wild-type isolate WCS358 increased tuber yield with 13% in a short rotation of potato 86 days after seeding, whereas a siderophore-negative Tn5 transposon mutant of this isolate had no effect on tuber yield. Seed tuber treatment with the wild-type isolate or the siderophore-negative mutant in a long rotation of potato had no effect on tuber yield. At 130 days after seeding no effect of any of the seed tuber treatments was found in both short and long rotations of potato.Root colonization by siderophore-producing Tn5 transposon mutants of WCS358 was decreased at the end of the growing season. No difference in root colonization between siderophore-producing and siderophore-negative Tn5 transposon mutants was found at 130 days after seeding.Siderophore production seems to be a prerequisite in potato tuber yield increase by WCS358 under field conditions. This is the first time that the involvement of siderophores in growth stimulation has been demonstrated in the field.Samenvatting De invloed van een behandeling van aardappelpootgoed metPseudomonas putida isolaat WCS358 op de knolopbrengst werd onderzocht in verschillende gewasrotaties on een proefveld van proefboerderij De Schreef, Flevopolder. In de controlebehandelingen werd in een nauwe aardappelrotatie (1:3) een reductie van 11% in opbrengst van pootaardappelen (86 dagen na het poten) geconstateerd ten opzichte van een ruime aardappelrotatie (1:6); 130 dagen na het poten werd een vermindering met 14% gevonden in de opbrengst van consumptieaardappelen.Pootgoedbehandeling met het siderofoorproducerende isolaat WCS358 verhoogde de opbrengst van pootaardappelen in de 1:3-rotatie met 13%. Een Tn5-transposonmutant van dit isolaat die het vermogen sideroforen te produceren had verloren, had geen effect op de opbrengst. In de 1:6-rotatie had behandeling van pootgoed met WCS358 geen effect op de opbrengst van pootaardappelen.Zowel in de nauwe (1:3) als in de ruimte (1:6) rotatie werd (130 dagen na het poten), geen effect van behandeling van pootgoed met WCS358 op de opbrengst van consumptieaardappelen gevonden.Wortelkolonisatie door siderofoorproducerende Tn5-transposonmutanten van WCS358 nam aan het eind van het seizoen af. Er werd, 130 dagen na het poten, geen verschil in wortelkolonisatie geconstateerd tussen siderofoorproducerende en siderofoornegatieve Tn5-transposonmutanten.Siderofoorproduktie blijkt een voorwaarde te zijn voor verhoging van de knolopbrengst door WCS358 onder veldomstandigheden. De verhoging van de knolopbrengst treedt alleen op in de nauwe aardappelrotatie. Dit is de eerste keer dat de betrokkenheid van sideroforen bij groeistimulatie onder veldomstandigheden is aangetoond.     

防治白菜根肿病的新型海洋微生物农药——解淀粉芽孢杆菌Txc2-1可湿性粉剂配方优化及药效研究

根肿病是十字花科作物的全球性重大病害之一,但可供选择的防治药剂非常有限。以本课题组筛选出的一株对十字花科白菜根肿病具有显著拮抗作用的海洋生境芽孢杆菌Txc2-1为研究对象,通过对载体和助剂的筛选以及采用混料设计确定Txc2-1可湿性粉剂最优配方,同时运用制备的30亿CFU/g可湿性粉剂进行盆栽试验和田间药效的考察。结果表明:Txc2-1可湿性粉剂最佳载体为轻质碳酸钙,最佳润湿剂为十二烷基硫酸钠,最佳悬浮剂为聚乙烯醇(PVA),这3种物质与Txc2-1菌株有较高的生物相容性,且具有良好的理化性能。通过混料设计确定其最优配比为m(轻质碳酸钙):m(十二烷基硫酸钠):m(PVA)=83:9:8。利用5 L罐培养液及上述配方进行喷雾干燥获得了30亿CFU/g Txc2-1可湿性粉剂(Txc2-1 WP);进一步盆栽(40 d)和田间(60 d)药效试验结果表明,Txc2-1 WP对白菜根肿病的防效分别达70.53%和66.84%。该解淀粉芽孢杆菌Txc2-1可湿性粉剂达到了国家质量标准,对白菜根肿病具有良好的防治效果,本研究结果为将Txc2-1开发成首个防治根肿病的海洋微生物杀菌剂奠定了基础。     

Simulation of herbicide use in a crop rotation with transgenic herbicide-tolerant oilseed rape

The potential impact of herbicide-tolerant winter oilseed rape ( Brassica napus L.) on future herbicide use was investigated with a simulation model. The model uses a sigmoid function to simulate the growth of crops and weeds that compete for a maximum yield potential. Thresholds for weed control are based upon critical levels of weed biomass. The dynamics of the weed population are determined by the efficacy of representative herbicides on individual weed species and by seedbank parameters. Herbicide efficacy is determined by a log-logistic dose–response curve for each species. Simulation of a rotation with winter oilseed rape/wheat/wheat/barley showed contradictory predictions of herbicide use, because herbicide use in a rotation with either glyphosate- or glufosinate-tolerant oilseed rape was not reduced in the amount of kg a.i. ha^–1 compared with a traditional treatment, whereas the treatment frequency (number of standard recommended doses per unit area) decreased.     

结球甘蓝抗根肿病SSR分子连锁图谱的构建

结球甘蓝(Brassica oleracea L.var.capitata)简称甘蓝,是我国重要的蔬菜作物之一.甘蓝根肿病是由芸苔根肿菌(Plamodiophora brassicae Woron.)侵染引起的一种世界性真菌病害.近年来,该病在我国的发病面积急剧增加,造成甘蓝产量和品质大幅度降低,选育抗病品种成为防治根肿病的重要途径之一.     

Effects of crop rotation and removal of crop debris on the soil population of two isolates of Verticillium dahliae

Microsclerotia of Verticillium dahliae are produced in large numbers on senescing parts of host plants and remain viable in the soil for many years. Changes in the population density, i.e. density of microsclerotia, in the soil were measured in micro-plots using two isolates of V. dahtiae , specific to either field bean or potato, several crop sequences comprising potato, field beans and barley, and either the removal of aerial debris of the crops or incorporation into soil.
Potato was more susceptible to the potato isolate and field bean more susceptible to the field bean isolate. Removal of debris of potato and field bean reduced numbers of microsclerotia in the soil in the subsequent years, but removal of barley straw had no effect. Initially non-infested control micro-plots became infested, probably by the growth of potato roots into the naturally infested subsoil. The rate of increase of the microsclerotial population in the non-infested control micro-plots was larger than in the initially infested treatments, because more colonized debris was produced. It is concluded that removal of aerial debris of host crops is important to reduce the soil population of V. dahtiae.     

Demography of Abutilon theoprasti and Setaria faberi in three crop rotation systems

Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2‐year (maize/soya bean) rotation, and in 3‐year (maize/soya bean/triticale + red clover) and 4‐year (maize/soya bean/triticale + lucerne/lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, Δ. In both years of the study, Δ for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3‐ and 4‐year rotations, increases in Δ for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, Δ remained stable in the 2‐year rotation, increased in the 3‐year rotation in both years, and increased in the 4‐year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop.     

Functional diversity of cover crop mixtures enhances biomass yield and weed suppression in a Mediterranean agroecosystem

Functional diversity of cover crop mixtures is thought to improve biomass production and weed suppression, two key agroecosystem services in organic systems. To test this hypothesis, we selected eight cover crop species belonging to four functional groups: (i) vining growing large-seeded legumes (field pea, common vetch), (ii) erect growing small-seeded legumes (crimson clover, squarrosum clover), (iii) grasses (barley, oats) and (iv) Brassicaceae (radish, black mustard). Nine cover crop mixtures were designed to create a gradient of diversity in terms of number of species and number of functional groups. A control treatment and all monocrops were included in the trial. Regarding cover crop biomass, mixtures outyielded monocrops by an average of 37%. Both functional identity and composition (i.e. trait complementarity) influenced biomass production and weed suppression provided by cover crops. Regression analysis showed that increase in both species diversity and functional diversity in cover crop mixtures improved the provision of agroecosystem services. Results from this study show that complementarity of species functional traits in cover crop mixtures can be used as a strategy to ensure high biomass production and good weed suppression in changing agroecosystems.