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1.
The control of seedborne rice seedling diseases in the seed beds is important to avoid epidemics in rice nurseries and paddies, which may result in severe yield loss. Recently, irradiation with plasma containing electrons, creating positive or negative ions and neutral species, has been shown to have an antimicrobial effect, probably via generation of reactive oxygen species. This study examines whether two seedborne rice seedling diseases, bakanae disease caused by the fungal pathogen Fusarium fujikuroi, and bacterial seedling blight caused by Burkholderia plantarii, are suppressed by irradiation of infected rice seeds with atmospheric plasma. Seed germination and seedling growth were not inhibited in plasma‐treated healthy seeds. When F. fujikuroi‐infected rice seeds were irradiated with plasma after being immersed in sterile distilled water, bakanae disease severity index and the percentage of plants with symptoms were reduced to 18.1% and 7.8% of non‐irradiated control, respectively, depending on the duration of plasma irradiation. The bacterial seedling blight disease index was also reduced by plasma irradiation in vacuum‐inoculated seeds to 38.6% of the non‐irradiated control, and in infected seeds harvested from spray‐inoculated heads of rice plants to 40.1% of the control. Therefore, plasma irradiation seems to be effective in controlling two independent seedborne rice seedling diseases.  相似文献   

2.
水稻白叶枯病自发现到现在已有90年的历史。由于发生地区广泛,为害严重,各国对此病曾做了大量研究。日本对它已研究了半个多世纪,我国也有二十多年的研究经历。但对其侵染来源和传播途径,仍有不同看法。我国最初认为种子传病是首要的。但在病区单抓种子处理还不能收到预期效果,又认为病稻草是病区次年的主要菌源。近年来,又发现在严格处理病革、病种子的情况下,仍然发病,故怀疑除上述两种传播途径外,还有其它传播途径。关于杂草传病问题,日本已进行了多年的研究,但和我国国内一样,对杂草带菌传病问题,意见很不一致。我们认为对这一传播途径有彻底弄清的必要,它不仅关系到一个病的侵染循环问题,而且直接关系到对白叶枯病的彻底防治。如果这一传播途径确实存在,我们若不承认它,在防治上就会出现大的漏洞。如果白叶枯病确与杂草无关,盲目地采用相应的措施,也是多余而毫无意义的。这次试验是采用较直接的“离心浓缩针刺接种法”,其结果:第一年证实有马唐等六种杂草、黄豆和水稻根部能够带菌;第二年证实有车前等三种杂草和水稻根不仅带菌,而且可越冬并存活到次年五月;第三年又证实在不同地区有马唐,狗牙根等四种杂草能够带菌越冬,并存活到次年五月中旬。另外,用病区杂草和水稻健苗混栽,结果稻苗上发病,而对照的不发病。通过三年来的试验研究,证实有数种杂草的根茎部不仅带菌,而且能传病。  相似文献   

3.
 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.  相似文献   

4.
The rapid range expansion of naturalized Italian ryegrass (Lolium multiflorum Lam.) in farmland is a serious problem in Fukuroi city in Shizuoka Prefecture, Japan. Glyphosate has been used to control Italian ryegrass in the levees of rice paddy fields and wheat fields for ～20 years, but this weed in Fukuroi city is poorly controlled by glyphosate. In order to elucidate the level of resistance to glyphosate in Italian ryegrass populations, seed bioassays and a foliar application experiment, using seeds collected from 16 wild populations in and around Fukuroi city and from three susceptible cultivars, were conducted. For the susceptible cultivars and one population from a site where glyphosate had not been applied for >10 years, the shoot length in the seed bioassays was greatly suppressed at a glyphosate concentration of 10 mg ai L?1 and no seedling survived after the foliar application of glyphosate at a rate of 2.3 kg ai ha?1. Nine wild populations from levees in the southern part of Fukuroi city showed vigorous shoot growth at a glyphosate concentration of 10 mg ai L?1 and had at least a 78% survival rate after the application of glyphosate at 2.3 kg ai ha?1. Four wild populations from levees in the northern part of Fukuroi city showed a slight suppression of the shoot growth as a result of the glyphosate treatment and their survival rates ranged from 20 to 64%. The results suggested that resistance to glyphosate has evolved in the wild populations of Italian ryegrass that are growing on the levees. This is the first report of a glyphosate‐resistant weed in Japan.  相似文献   

5.
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6.
Leaf blight disease of water hyacinth was observed and collected from different geographical areas of Thailand. The disease is caused by a fungal pathogen that was identified as Myrothecium roridum by using its morphological characteristics. The most effective fungal strains were evaluated for pathogenicity on water hyacinth under greenhouse and natural conditions. Myrothecium roridum isolate, Kamphaeng Sean Campus (KKFC) 448, was found to be the most virulent. Different fungal formulations were evaluated for their level of control of water hyacinth. The results showed that spore suspensions with 10% palm oil or 1% Tween 20 caused a higher level of disease severity, compared to spores applied in water alone. The host range of KKFC 448 was evaluated by using 77 plant species that belong to 40 plant families. The fungus did not cause disease on 74 economically important plants but did produce disease signs on water hyacinth and two other aquatic weeds, duckweed and water lettuce. Leaf blight occurs on water hyacinth leaves after being treated with crude extracts of M. roridum and it was indicated that secondary metabolites were released from the fungal mycelia. Myrothecium roridum that was grown on boiled paddy rice produced β‐1,4‐exoglucanase, β‐1,4‐endoglucanase, β‐glucosidase, xylanase and pectinase more than Mroridum that was grown on potato dextrose agar. The results indicated that M. roridum is a pathogen of water hyacinth and the fungus is capable of producing different enzymatic activities on potato dextrose agar and boiled paddy rice, which might be important for infection.  相似文献   

7.
Echinochloa oryzicola Vasing. (= Echinochloa phyllopogon Stapf ex Kessenko) is an obligate weed with an elaborated survival strategy in the flooded rice of Japan. In this review various adaptive characters of the weed, which comprise the survival strategy, are discussed through the life cycle. The weed is distributed only in flooded rice. Seeds (spikelets) buried in the soil exhibit annual cycles between dormant and non‐dormant state, and non‐dormant seeds recurrently appear in spring when rice growers start to prepare seedling beds and fields for rice transplanting. The non‐dormant seeds have unique characters metabolically adapted to submerged conditions to germinate and grow by the anaerobic respiration through alcohol fermentation. The weed has seemingly perfect mimicry of the rice plants throughout its development from seedling to heading, by which the weed escapes from manual weeding. In a rice paddy, the weed starts heading coincidentally with the rice plants at the period when the growers are reluctant to walk in the rice paddy to weed. Irrespective of plant height of the rice cultivar, the weed develops a few upper leaves above the rice canopy during the heading period of rice. This phenotypic plasticity of E. oryzicola in plant height is one of the characters conferring its competitive aggressiveness in flooded rice. When weeding is begun again after heading, the dormant weed seeds escape weeding by shattering and join the soil seedbank. The dormant seeds express the gene of an enzyme catalyzing ATP synthesis through the mitochondrial oxidative phosphorylation more abundantly, and have larger oxygen absorption and enzyme activity of the aerobic respiration than the non‐dormant seeds, suggesting that the dormant seeds maintain viability by the conventional aerobic respiration in the paddy soil drained from rice harvesting in fall to the next early spring. The various adaptive characters comprising the survival strategy of E. oryzicola in flooded rice consist of those inherited from the wild progenitor and those selected by the crop cultivation pressure. It is suggested that both the mimicry of the weed and the heading coincident with the rice plants have been acquired by the large selection pressure of frequent weeding, which has been done over the past hundred years. However, today, the manual weeding is substituted with herbicides, which cannot detect the mimicry and heading photoperiodic sensitivity. As a result, the dominant species of Echinochloa weeds in flooded rice is changing from E. oryzicola to Echinochloa crus‐galli var. crus‐galli that has neither mimicry nor photoperiodic sensitivity synchronizing to that of rice, but is more competitive against rice.  相似文献   

8.
为鉴定云南稻种质资源对水稻白叶枯病的抗性情况,于孕穗期采用剪叶接种方法,用水稻白叶枯病强致病型代表菌株BD8438、CN9404和X1接种云南野生稻和地方稻种质资源,以病斑长度大于6 cm为感病分界线,对其抗感表现型进行调查分析。结果显示,共鉴定出来源于云南省不同种植生态区的186份地方稻抗性材料和22个野生稻抗病居群。野生稻对水稻白叶枯病的抗病能力较地方稻强,其中疣粒野生稻的抗性最强,抗病等级为0~2;药用野生稻次之,抗病等级为1~2;普通野生稻相对较差,抗病等级为1~5。地方稻抗性资源来自于云南省各个传统水稻种植区,抗性1级的材料占17%,抗性2级的占2%,抗性3级的占81%;按照稻种质资源亚种类型、粘糯性和水旱性分类,各类型地方稻抗性材料所占比例分别为粳稻占61%、籼稻占39%;粘稻占66%、糯稻占34%;水稻占83%、陆稻占17%。从利用抗白叶枯病基因培育新品种的角度评价,这些抗性资源具有潜在的发掘利用价值。  相似文献   

9.
The economic impact of seedborne bacterial diseases on rice production provides a major motivation for research on seed health. This paper reports on the endophytic growth of a rifampicin‐marked strain of the seedborne rice pathogen Pseudomonas fuscovaginae. The bacterium was found in most tested seeds indicating that, even without visible discolouration, seed transmission is possible. Crushed discoloured seeds contained more bacterial cells than did non‐crushed discoloured seeds. These bacteria were released during seed soaking, contaminating clean seed and lowering seed germination. Cells of a rifampicin‐resistant strain of P. fuscovaginae, which had been inoculated onto rice seeds, were subsequently recovered from different growth stages and from different rice tissues, thereby indicating endophytic colonization. These results have implications for seedling establishment, as symptomless seeds do not assure disease‐free seeds, and the presence of seedborne bacteria results in poor germination and poor seedling establishment. Elimination of seedborne bacteria by soaking in sodium hypochlorite can increase seed germination. This could be used in developing control strategies, and, if practised regularly, reduce entry of seedborne disease‐causing organisms into crops, resulting in lower disease pressure.  相似文献   

10.
The application of allelopathic plant materials combined with an agricultural production method is a concept that can be used to manage weeds during rice production. This research investigated the effects of the utilization of Bidens pilosa var. radiata integrated with water irrigation for weed control and rice production. B. pilosa and water extract exerted more toxicity against Echinochloa crus‐galli than the extracted residue applied at the same rates, suggesting that weed control was caused by compounds extracted from B. pilosa. The changes in water properties after the application of B. pilosa were explored. Dissolved oxygen was rapidly reduced after application and then slowly increased within 3–5 days after application (DAA), while the pH also decreased at the early stage and then increased back to normal values within 1–3 DAA. Electrical conductivity increased with increasing rates of application, suggesting that allelochemicals were released from B. pilosa. The concept was studied under field conditions. B. pilosa was applied along with irrigation at 7 days after sowing (DAS) on a direct wet seed system. The results showed that application rates of 2, 4 and 6 tons ha?1 decreased the number of weeds by 52.16, 86.73 and 95.18% at 30 DAA and reduced dried weight of weeds by 17.65, 34.69 and 86.82%, respectively. The rice yield showed an increase of 72.73, 81.03 and 73.66% when compared with the nonweeded crop, while herbicide treatment increased by 84.68%. The findings demonstrate that the application of B. pilosa integrated with water irrigation was able to control weeds in a direct seeded rice production system.  相似文献   

11.
植物伯克霍尔德菌Burkholderia plantarii是引起水稻秧苗细菌性立枯病的重要病原菌之一,其侵染性、繁殖力及适应性均很强,严重威胁中国水稻生产。文章围绕B.plantarii的发生、危害及致病机理,着重论述了细菌群体感应系统(quorum sensing,QS)的生理功能及其在B.plantarii致病力调控方面的最新研究进展,并进一步从根际微生物互作角度,综述了种间信号分子对病原菌群体淬灭(quorum quenching)的作用机制,同时结合种间信号分子的独特性,展望了其在新型微生物杀菌剂研发中的重要性和应用潜力。  相似文献   

12.
Anthracnose disease was found on centipede grass [Eremochloa ophiuroides (Munro) Hack.] planted as a ground cover on paddy field levees in Shiga Prefecture in 2004. The symptoms were ear blight, stalk blight, and leaf spots. The causal fungus was morphologically identified as Colletotrichum caudatum (Sacc.) Peck. This is the first report of centipede grass anthracnose caused by C. caudatum.  相似文献   

13.
胡蓉  郑露  刘浩  黄俊斌 《植物保护学报》2020,47(6):1261-1269
为探究稻麦轮作模式下秸秆还田对水稻根际微生物多样性与水稻纹枯病发生的影响,本研究采用Illumina测序技术结合生物信息学比较分析了秸秆还田与不还田处理的水稻根际微生物群落多样性差异,并采用实时荧光定量PCR （real-time fluorescent quantitative PCR,RT-qPCR）对这2种稻田土壤中水稻纹枯病菌Rhizoctonia solani含量进行测定,并采用随机五点取样法调查稻田中水稻纹枯病发病率和病情指数。结果表明,秸秆还田后水稻根际细菌群落Chao1丰富度指数和Shannon多样性指数均有所增加,分别增加14.42%和4.39%,其中前者增幅显著;根际真菌群落Chao1丰富度指数降低29.60%,而Shannon多样性指数略有增加,增加5.96%;在门水平上,秸秆还田和不还田处理的水稻根际土壤优势细菌门均为变形菌门、放线菌门、绿弯菌门和酸杆菌门,优势真菌门均为子囊菌门、接合菌门和担子菌门;在属水平上,秸秆还田处理的硝化螺旋菌属和芽胞杆菌属相对丰度分别比不还田处理的显著增加96.11%和106.19%;在水稻孕穗期秸秆还田土壤中水稻纹枯病菌含量比不还田处理的显著增加120.20%;秸秆还田后水稻纹枯病发生加重,病情指数比不还田处理的增加18.10%~45.41%。  相似文献   

14.
应用噬菌体测定水稻白叶枯病带菌稻种内存活细菌数量的技术,初步找出0.5％盐酸浸种72小时和每毫升含500单位氯霉素浸种48小时,是杀死稻种内病原细菌有效的方法。噬菌体技术必为今后稻种处理药剂的筛选提供一个准确而可靠的方法。  相似文献   

15.
To quantify the effect of weeds on the nitrogen (N) use, growth and yield of wet season paddy rice in the central and northern regions of Laos, we surveyed the paddy fields in these regions in October 1999 and November 2000. We found 13 weed species in total, but there were few major weeds abundant at the survey sites. In the infertile soils under rainfed conditions, weed growth was poor. Rough rice yield, the number of panicles, the number of seeds per square meter, the above-ground biomass of paddy rice and the amount of N accumulated in the above-ground biomass of paddy rice (amount of N in rice) were suppressed by competition with weeds. However, harvest index (HI) and nitrogen use efficiency (NUE) of paddy rice were not suppressed by competition with weeds. The amount of N in rice was suppressed by competition with weeds, the number of panicles decreased as the amount of N in rice decreased, and the number of seeds per square meter decreased as the number of panicles decreased. As a result, rough rice yield was suppressed by competition with weeds. The weeds competed with paddy rice for N uptake during the productive tillering stage. However, the ability of paddy rice to compete for N uptake with weeds was not reduced under rainfed lowland conditions. When the weeds were completely removed, the amount of N in rice increased. Rough rice yield may be increased by 10% under rainfed lowland conditions and by 17–19% under irrigated conditions.  相似文献   

16.
Italian ryegrass ( Lolium multiflorum Lam.) is a non‐native annual winter grass that has seriously infested rice paddy levees and wheat fields in Japan. Recently, glyphosate‐resistant Italian ryegrass was found on paddy levees in central Japan, thereby making control of the grass by using glyphosate less effective. In this study, physical control methods were tested that combined the timing and frequency of mowing in order to more effectively control glyphosate‐resistant Italian ryegrass on rice paddy levees. A 3 year field experiment was conducted from 2012 to 2014 in a western region of Shizuoka Prefecture, where glyphosate‐resistant Italian ryegrass has become dominant. Five treatments were tested: (i) mowing once before the flowering of the grass (i.e. conventional mowing measure); (ii) mowing once during flowering; (iii) mowing twice during flowering; (iv) glyphosate application before flowering (i.e. one of the conventional mowing measures); and (v) no treatment. The above‐ground biomass, seed production, soil seed bank and seedling occurrence of Italian ryegrass were measured to determine the effectiveness of these treatments. Mowing during the flowering period resulted in reduced above‐ground biomass, seed production and soil seed bank when compared with the other treatments. Additionally, mowing twice during the flowering period resulted in a lower seedling density than mowing once. The results suggest that, in this region, physical control by mowing during the flowering period would be more effective than conventional measures for controlling glyphosate‐resistant Italian ryegrass.  相似文献   

17.
研究了稻田施用氯氟吡氧乙酸后,其在水稻植株、糙米、稻壳、稻田土壤和田水中的残留动态。样品采用氢氧化钠-甲醇溶液振荡提取,二氯甲烷液液分配,甲酯化后经气相色谱-电子捕获检测器(GC-ECD)测定。结果表明:氯氟吡氧乙酸在水稻植株、稻田土壤、田水、糙米和稻壳中的平均 回收率在85.5% ~103.2%之间,相对标准偏差在1.9% ~9.9%之间;其最小检出量为2.0×10-12g, 在植株、糙米、稻壳、土壤和田水中的最低检测浓度分别为 0.005,0.02,0.005,0.002 mg/kg 和0.001 mg/L。2007和2008年在安徽潜山、广东广州两地的田间残留试验结果表明:氯氟吡氧乙酸在水稻植株中的降解半衰期为4.9 ~6.0 d,土壤中为5.5 ~8.6 d,田水中为11.0~13.8 d;收获的糙米中氯氟吡氧乙酸的最终残留量在未检出~0.13 mg/kg之间,均低于其在糙米上的最大残留限量(MRL)值0.2 mg/kg(中国)。建议5%氯氟吡氧乙酸可湿性粉剂用于防治水稻田杂草时,施药剂量按有效成分计不得超过168.8 g/hm2,于返青期施药1次。  相似文献   

18.
Recently, glyphosate‐resistant Italian ryegrass (Lolium multiflorum Lam.) was found on rice paddy levees in a western region of Shizuoka Prefecture, Japan. Naturalized populations of Italian ryegrass are frequently infected with fungal Epichloë endophytes. Endophytes often confer benefits to their host grasses. This study investigated the influence of five weed management treatments on glyphosate resistance and endophyte infection in Italian ryegrass that was growing on paddy levees where glyphosate‐resistant individuals were dominant. The weed management treatments were: (i) mowing once before the grass flowered; (ii) mowing once during flowering; (iii) mowing twice during flowering; (iv) glyphosate application before flowering; and (v) no treatment. The seeds were collected from the treatment plots in 2013 and 2014. The seeds were examined for endophyte infection and the seedlings that had been grown from the seeds were tested for the frequency of glyphosate resistance. The seedlings that had been derived from the glyphosate treatment showed higher frequencies of glyphosate resistance than those seedlings that had been derived from all the other treatments. Endophytes were found in all populations of the seeds from the paddy levees, with higher infection rates in the seeds that had been derived from the glyphosate treatment and the twice‐mowed treatment. There was a significant relationship between the endophyte infection frequency in the seeds and glyphosate resistance in the seedlings that had been grown from the same populations. The results indicate that where glyphosate herbicides are frequently used, selection for glyphosate‐resistant Italian ryegrass occurs, and along with this, the frequency of endophyte infection also increases.  相似文献   

19.
Molinate, a selective herbicide, is used for the control of annual and perennial weeds in rice paddy fields. This study was designed to assess the basis of the selective action of molinate between a susceptible broadleaf crop, tobacco, and a resistant graminaceous plant, rice. Experiments were conducted comparing plant growth under different concentrations of molinate, determining the absorption and translocation of the herbicide in the plant and identifying the metabolites in suspension cells. Rice showed greater tolerance to molinate than tobacco. Leaves of tobacco showed retarded and distorted growth at 10 mg liter-1 of molinate 14 days after treatment, but rice leaves were unaffected at this concentration. Higher concentrations of molinate accumulating in the root of tobacco seedlings may inhibit root development and represent a significant factor in the herbicide's selective action. Seven and eight metabolites were found in tobacco and rice cells, respectively, with molinate sulfoxide and molinate sulfone present in both species. © 1998 SCI  相似文献   

20.
灭草特在水稻秧田应用技术研究   总被引：1，自引：1，他引：0  
在毒鼠时机、毒饵布放位置及药物剂量一致的条件下,用不同饵料防治稻田害鼠,O.005％大隆稻谷毒饵灭鼠效果达91.8％,0.005％大隆大米毒饵灭鼠效果为79.6％。0.2％敌鼠钠盐稻谷毒饵灭效则为96.2％。以相同的或不同的大隆剂量、不同饵料、不同加药方法对4组笼养黄毛鼠作1次投毒试验,其结果与急性杀鼠剂1次毒杀效果相同,但试鼠呈慢性死亡过程。剖检症状为内出血。本试区仅初次使用第一代抗凝血剂——敌鼠钠盐,尚未产生抗药性的老鼠种群。大隆杀鼠剂,可作为今后出现“超级老鼠”时的接替品种。  相似文献   

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