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1.
High concentrations of the mycotoxin deoxynivalenol (DON), produced by Fusarium graminearum have occurred frequently in Norwegian oats recently. Early prediction of DON levels is important for farmers, authorities and the Cereal Industry. In this study, the main weather factors influencing mycotoxin accumulation were identified and two models to predict the risk of DON in oat grains in Norway were developed: (1) as a warning system for farmers to decide if and when to treat with fungicide, and (2) for authorities and industry to use at harvest to identify potential food safety problems. Oat grain samples from farmers’ fields were collected together with weather data (2004–2013). A mathematical model was developed and used to estimate phenology windows of growth stages in oats (tillering, flowering etc.). Weather summarisations were then calculated within these windows, and the Spearman rank correlation factor calculated between DON-contamination in oats at harvest and the weather summarisations for each phenological window. DON contamination was most clearly associated with the weather conditions around flowering and close to harvest. Warm, rainy and humid weather during and around flowering increased the risk of DON accumulation in oats, as did dry periods during germination/seedling growth and tillering. Prior to harvest, warm and humid weather conditions followed by cool and dry conditions were associated with a decreased risk of DON accumulation. A prediction model, including only pre-flowering weather conditions, adequately forecasted risk of DON contamination in oat, and can aid in decisions about fungicide treatments.  相似文献   

2.
High occurrence of Fusarium poae (FP) and Fusarium langsethiae (FL) and their mycotoxins nivalenol (NIV) and T-2/HT-2 have been observed in Swiss oats. Early prediction of mycotoxin levels is important for farmers and the cereal industry to minimize the risk of contaminated food and feed. Therefore, climate chamber experiments were conducted to investigate the influence of different temperatures (10, 15, 20 °C) and durations (4, 8, 12 h) at 99% relative humidity (RH) on the infection of oats with FP and FL. In addition, to discover the most susceptible period of oats, artificial FL inoculations were conducted at different growth stages. Field experiments were performed to observe the dispersal of these fungal species within the field and to investigate the weather conditions that influence the dispersal. The climate chamber experiments revealed higher contamination with NIV and T-2/HT-2 in the 10 °C treatments and with a prolonged humidity duration of 12 h 99% RH. Inoculations of oat plants at early (DC 61) and mid (DC 65) anthesis, led to higher FL infection and T-2/HT-2 accumulation in the grains compared with treatments at earlier growth stages, which might be due to an increased susceptibility during anthesis. No indication for spore dispersal was observed in the field experiments. The results obtained, together with the cropping factors that influence infection and mycotoxin production, could be used as a first step in developing forecasting models to predict the contamination of oats with the mycotoxins NIV and T-2/HT-2.  相似文献   

3.
A field survey was performed to study the infection and development of Fusarium langsethiae in the growing season of wheat, barley, oats and triticale under commercial (2009 – 2011) production. Sampling was completed over three years from fields within the counties of Shropshire and Staffordshire in the UK. Plants sampled (from tillering to harvest) were divided into roots, leaves, lower stem, upper stem and inflorescence/head sub-samples depending on the growth stage of the cereal. DNA was extracted and F. langsethiae DNA quantified using real-time PCR. Fusarium mycotoxins HT-2 and T-2 were quantified from head samples at harvest. Three years of data showed oat to contain the highest levels of both F. langsethiae biomass and HT-2?+?T-2 mycotoxins in harvested heads of the cereals studied. The development of F. langsethiae in all three cereals appeared to be similar. Fusarium langsethiae DNA was not detected in the roots and seedlings of all three cereals suggesting F. langsethiae is not a seedling pathogen of cereals. Head infection if it occurs, is at head emergence but before flowering. Seemingly symptomless heads had high levels of F. langsethiae DNA and HT-2?+?T-2, confirming previous suggestions that F. langsethiae is a symptomless pathogen of oats.  相似文献   

4.
Infestation of kiwifruit flowers by Thrips obscuratus , and inoculation with Botrytis cinerea , increased the amount of flower infection, external contamination and internal infection of fruit at harvest. Combination of these treatments was synergistic. The mechanisms of this role of T. obscuratus in the epidemiology of B. cinerea and development of stem-end rot after cool storage are discussed in relation to commercial production, harvesting and handling procedures. Significant reductions in inoculum available for fruit infection may be achievable by control of populations of T. obscuratus in orchards during flowering.  相似文献   

5.
A. fauta reduced yields of spring barley in the majority of 51 experiments carried out during 1971 and 1972. Infestations ranging from 8 to 662 seedlings/m2 in the spring resulted in yield reductions varying from nothing to 72%; in 11 experiments these exceeded 1–2 t/ha. Reductions in yield were poorly correlated with numbers of seedlings, panicles or wild oat seeds produced. However, there was a good correlation between yield loss and the dry weight of wild oats at harvest. Growth and competitive effects of wild oats differed between the two years. Grain losses were due mainly to reductions in the numbers of ear bearing barley tillers. The influence and significance of the effect of competition on the size of barley grains is discussed.  相似文献   

6.
Summary. Survival of wild oat seeds (mainly Avena fatua ) under leys on clay soils was investigated in two field experiments. During the first year under ley the number of seeds decreased by 41 % and 86% respectively. Subsequent decreases were less, and after 5 years under ley there were still enough of the original seeds left to produce infestation of a cereal crop. These results suggest that a long ley is not an efficient way of eliminating wild oat seeds from soil, and that a 1-year ley may be almost as effective as one of 5 years.
When a ley was ploughed, the number of wild oats germinating decreased as the number of years under ley and the age of the seeds increased, but was scarcely affected by the weather. In contrast, charlock ( Sinapis arvensis ) germination did not decrease with increasing age of seeds up to 5 years, but was greatest in years with most rain during April and May.
Survivance de semences de Folle Avoine (Avena fatua L . et A . ludovieiana Dur.) et de Moutarde des champs (Sinapis arvensis L.) dans le sol sous prairie temporaire  相似文献   

7.
在大田环境下,研究了5种旧膜处理方式对旱地胡麻生育进程中叶面积、干物质累积、净同化率（NAR）、相对增长率（RGR）及产量和产量构成因子的影响。结果表明：在花前营养生长期,播种前收除旧膜并覆盖新膜免耕播种（T4）与当年收除旧膜并整地覆盖新膜、翌年播种（T5）处理较当年全膜覆盖作物收获后收除旧膜、翌年整地播种（T6）（无覆膜对照）对提高胡麻叶面积影响最为显著,但花期及花后各处理与对照相比无显著差异。胡麻总干物质在花前T4、T5处理较T6积累量最多,其中分器官茎、叶干物质呈现相同趋势,花后T5处理跃居首位。NAR因处理和生育时期不同而有所差异,表现为生育前期T4高于其它处理,生育后期T5处理最优的结果;RGR在枞形期-现蕾期T4、T5处理较对照分别上升20.45%和16.12%,而花期T5处理表现最高,二者均呈现出与其干物质积累动态相一致的趋势。5种处理方式均提高了有效分枝数和千粒重,对蒴果数和每果籽粒数影响不大,其中T4、T5处理下胡麻籽粒产量分别达到了1 024.95 kg·hm-2和996.15 kg·hm-2,比对照显著增产120.91%、114.71%,旧膜留至翌年免耕播种（T1）、在旧膜上覆土免耕播种（T2）、当年作物收获后在旧膜上覆盖玉米秸秆、翌年去除秸秆免耕播种（T3）与对照T6产量差异不显著。可见,收获后留旧膜、翌年收旧膜覆新膜免耕播种的处理方式有利于提高生长速率和干物质累积,进而获得高产,而结合生产效益,收获后留旧膜翌年直接播种（T1）方式为干旱半干旱胡麻种植区旧膜再利用的最优选择。  相似文献   

8.
Barban was combined with benzoylprop ethyl, flamprop methyl, or flamprop isopropyl, and the eflects of the combinations on wild oat control and crop yield were assessed, tn greenhouse experiments, the interaction in all three combinations was synergistic, following application at the 2- or 4-leaf stage of wild oats. Under field conditions, combinations of barban + benzoylprop ethyl applied at the 2- or 4-leaf stage of wild oats were as eflective for wild oat control and wheat yield response as barban at 028 kg/ha applied at the 2-leaf or benzoylprop ethyl at 14 kg/ha applied at the 4-leaf stage of wild oats. Mixtures of barban + flamprop methyl applied at the 2- or 4-leaf stage of wild oats provided excellent wild oat control and wheat yield increases. Mixtures of barban + flamprop isopropyl applied at the 2- or 4-leaf stage of wild oats provided comparable wild oat control and barley yield increases to barban (028 kg/ha) applied at the 2-leaf or flamprop isopropyl (14 kg/ha) applied at the 4-leaf stage of wild oats.  相似文献   

9.
Anthracnose and crown rot are the main diseases affecting bananas after harvest. These diseases are mainly caused by Colletotrichum musae (anthracnose) and to some extent by various Fusarium species forming a fungal complex (crown rot). A water-borne spore trap was used to collect and quantify all inocula reaching banana bunches from flowering to harvest. The pattern of natural contamination was characterized by a peak from 25 to 40 days after bunch emergence, with a strong decline until harvest. Both Colletotrichum and Fusarium species had the same dynamics during bunch growth. Flower parts are the main inoculum source for Fusarium; both flower parts and the last bunch bract are important sources for Colletotrichum . Primary inoculum could reach flower parts and the last bunch bract through rain splash of conidia, transport by insects or aerial dissemination of ascospores. Sporulation occurring on the young flower parts and on the last bunch bract provides heavy secondary inoculum. The consequences for control strategies are discussed.  相似文献   

10.
Summary. The object of the work described in this paper was to obtain information on the relationship between the effects of crop competition and barban treatment on oats growing in another cereal. The work was carried out on barley cross-drilled with cultivated oats. Variation in crop competition was obtained by using different barley seed-rates and nitrogen levels. Increasing the seedrate of barley without applying barban resulted in a reduction of the initial oat population. This reduction applied to weight of individual shoots, number of shoots and panicles per unit area and number of spikelets per panicle. The application of barban at selective rates gave an independent reduction of oats of the order of 80%. This value proved almost constant at each seedrate of barley. Crop competition and barban accordingly seem to art independently and their effects appear to be simply additive. The barley fresh weights per unit area increased substantially when oat competition was reduced by barban treatment. The highest increase occurred on the plots with the lowest barley seedrate in spite of the fact that these plots still appeared infested with oats at harvest time. Nitrogen application stimulated the growth of barley and oats to a similar degree and did not in consequence lead to a selective suppression of oats.
Etude de l'influence de la densité du Semis, du taux de fertilisation azotée et du traitement au barbane, sur la concurrence entre une Orge et une Avoine  相似文献   

11.
Different populations of Colletotrichum were characterized and quantified on floral parts of banana plants from flowering until harvest. Isolates of Colletotrichum found to be pathogenic and attributed to the species C. musae (77% of isolates) were differentiated from other species by abundant sporulation, a short mycelium, and rapid growth. Colletotrichum musae was isolated from floral parts mainly during the month following bunch emergence. The respective involvement of different sources of inoculum (leaves, bunch bracts, floral parts) in the levels of fruit contamination was evaluated. When the floral parts and bunch bracts were removed at flowering, the severity of anthracnose disease was considerably reduced. The severity of the disease is strongly correlated with cumulative rainfall during the first 35 days after bunch emergence, and was considerably reduced when rainwater runoff over the bunches was limited by placing plastic sleeves over them. The disease was not observed on banana fruit grown under shelters, protected from rain. The results obtained from this study show clearly that contamination of fruit by conidia takes place largely due to the trickling of rainfall over the floral parts, which are the main source of inoculum. The application of these results for integrated control is discussed.  相似文献   

12.
水稻穗腐病病菌致病性、发生规律及防控技术研究   总被引：3，自引：0，他引：3  
穗腐病是近年发生危害严重的水稻穗部病害.本研究对穗腐病的发生、流行原因进行了分析,分离了病原菌并测定了致病性,筛选了防治该病的杀菌剂并进行了田间防效试验.结果表明,紧穗型的粳稻及籼/粳杂交稻组合较穗型松散的籼稻及其杂交组合更易感病.水稻孕穗后期-抽穗扬花期遇阴雨高湿、温暖天气该病发生危害重.用分离到的4个菌(层出镰刀菌、澳大利亚平脐蠕孢菌、新月弯孢菌和细交链孢菌)进行人工接种,均能使稻粒感病,初步确定层出镰刀菌为主要初侵染菌.室内抑菌测试结果显示,5 mg/L以上浓度的多菌灵、咪鲜胺和苯醚甲环唑·丙环唑(爱苗)对层出镰刀菌生长的抑制效果达到81.31％～100％.抑制中浓度为0.000 7～0.947 6 mg/L.田间试验结果表明,在水稻孕穗后期和抽穗扬花期用三唑酮、多菌灵或甲基硫菌灵喷雾防治一次,防效在70％左右.  相似文献   

13.
Fusarium head blight is one of the most serious cereal diseases of the world. Epidemics of Fusarium head blight can lead to a decline in grain quality and yield. In addition, grains often become contaminated with mycotoxins, which are harmful to humans and animals. In a field survey of winter wheat in Switzerland, Fusarium graminearum proved to be the most prevalent species responsible for head blight and deoxynivalenol the most common mycotoxin. To elucidate and quantify single or combined effects of cropping factors on F. graminearum infestation and to reduce the risk of mycotoxin contamination of wheat under conservation tillage, we developed the decision support system FusaProg. Our model takes into account the effects of cropping factors, previous crops, soil and straw management, as well as the F. graminearum susceptibility of the planted variety. These factors are used as driving variables and are combined with the prevailing weather conditions and growth stage in order to predict the deoxynivalenol content of a specific wheat plot before harvest. To use FusaProg as a threshold‐based tool to control F. graminearum with optimized timing of fungicide applications, forecasts of deoxynivalenol contents are conducted during the flowering period. FusaProg is an Internet‐based decision support system which not only provides information about the local and regional F. graminearum infection risks; it also forecasts plot‐specific deoxynivalenol contamination of winter wheat. In 2006, the system was evaluated by Swiss cantonal plant protection officers, and in 2007, the system will be made available to Swiss wheat producers.  相似文献   

14.
Fusarium head blight (FHB) is an important disease of wheat, which can result in the contamination of grains with mycotoxins such as deoxynivalenol (DON). Artificial inoculation of flowering ears with conidial suspensions is widely used to study FHB diseases. Our goal was to compare four inoculation treatments in which a conidial suspension was sprayed on flowering ears and to study the effect of the application of moisture during kernel setting and filling with a mist-irrigation system. Ten wheat genotypes were inoculated with a DON-producing Fusarium culmorum strain. Inoculation treatments varied in time of application of the inoculum (morning or evening) and in the method of controlling humidity during inoculation (bagging or mist irrigation). A wet season was simulated with a mist-irrigation system, keeping the crop canopy wet for at least 26 days after flowering. The severity of FHB symptoms (area under disease progress curve (AUDPC)), yield loss and DON contamination in the grains were determined. AUDPC data obtained with the different inoculation treatments were highly correlated (r=0.85–0.95). Mist irrigation after inoculation resulted in a higher mean disease severity, but in a overall lower toxin contamination as compared to the non-irrigated treatments. Genotypic differences in DON accumulation were present: for one wheat line toxin contamination significantly increased when irrigated, while two genotypes accumulated significantly less toxin. The closest relationships (r=0.73–0.89) between the visual symptoms and the DON content were obtained under moderate mean infection pressure. This relation between visual symptoms and the DON content deteriorated at higher infection levels.  相似文献   

15.
Summary. This project was designed to study various aspects of wild oat competition in spring wheat and flax. From ten to forty wild oat plants/yd2 were sufficient to cause significant yield reductions in wheat when grown on summerfallow land or when ammonium phosphate fertilizer was added to stubble land. However, when wheat was grown on stubble land without the benefit of a fertilizer treatment, seventy to one hundred wild oat plants/yd2 were needed to suppress wheat yields significantly. This would suggest that on stubble land, soil fertility was a more important factor than moderate densities of wild oats in determining eventual crop yields. In these experiments, wild oats reduced the number of tillers per plant, but did not significantly affect the protein content of the harvested grain. Only ten wild oat plants/yd2 were sufficient to reduce flax yields significantly on both summerfallow and stubble land. The only exception was in 1966, when flax grown on summerfallow land was not significantly affected until the density of wild oats reached forty plants/yd2. This confirms the general observation that flax is a poor competitor with wild oats. The results suggest that wild oat competition had already commenced prior to emergence of wheat, particularly with the higher densities of wild oats. In general, competitive effects increased with time and with wild oat density. In flax, severe competition had already taken place prior to the 2–3-Ieaf stage of the weed in 1964, but did not become severe until after the 2–3-leaf stage of wild oat growth in 1965 and 1966. Again, competitive effects increased with time and with wild oat density. Results of a final series of experiments, suggested that the optimum seeding date for flax in Manitoba is the latter part of May or the first week of June. Yield reductions due to wild oat competition became very severe as seeding dates were delayed. La compétition de la folle avoine (A vena fatua L.) avec le blé et le lin  相似文献   

16.
在大田试验条件下,以陇亚杂1号为材料,设置不灌水(CK)、分茎水80 mm(T1)、分茎水60 mm+盛花水40 mm(T2)、分茎水80 mm+盛花水40 mm(T3)、分茎水60 mm+现蕾水40 mm+盛花水40 mm(T4)5个处理,研究了不同水分处理对胡麻干物质积累与分配、籽粒产量及其水分利用效率的影响。结果表明:与CK相比,灌水处理显著提高开花后干物质的积累量和开花后干物质积累量对籽粒的贡献率,以T2处理最高,分别增加了91.37%、45.09%;灌水量过多显著减少光合产量向籽粒的分配,使籽粒产量降低;随灌水量增加,胡麻全生育期耗水量显著增大,籽粒产量先升高后降低,灌水利用效率显著降低;T2处理的产量和水分利用效率显著高于其他处理,分别比CK增加了40.72%、11.71%。综合考虑胡麻的籽粒产量和水分利用效率,T2处理为本试验条件下高产节水的最佳灌水处理。  相似文献   

17.
以品五(晚熟品种)和坝莜一号(早熟品种)两个裸燕麦(莜麦)品种为试验材料,对其不同时期的根系体积和根系表面积的变化动态进行了研究。结果表明:裸燕麦两个品种中后期根系总体积的变化趋势基本一致,大致可分为:拔节期到抽穗开花期的快速增长阶段、抽穗开花期至开花后10~26 d的显著下降阶段、开花后10~26d至成熟期的缓慢上升阶段。通过对裸燕麦不同时期分层根系体积和表面积的分析,30~90 cm土层中根系的继续增长导致其生育后期根系表现回升性增长特性。裸燕麦晚熟品种生育中后期根系体积、根表面积、根系干重等性状间呈极显著正相关;早熟品种除根系干重与根系表面积之间相关不显著外,其他各性状之间均呈极显著正相关关系。  相似文献   

18.
基于沧州市1961—2018年58 a逐日降水量、气温、空气相对湿度、日照气象资料和1998—2017年19 a沧州金丝小枣产量及枣园灾害调查资料,采用金丝小枣生长期气象灾害判别指标分析得出:金丝小枣不同生长期的主要气象灾害是萌芽展叶期高温、开花坐果期高温低湿、果实膨大期高温日灼、果实白熟期和成熟收获期连阴雨天气。通过概率统计和层次分析法(AHP)对这种灾害变化特征及权重进行统计计算和检验分析。结果表明:(1)金丝小枣萌芽展叶期高温、开花坐果期高温低湿、果实膨大期高温日灼年发生频率100%,果实白熟期、成熟收获期连阴雨年平均发生频率为37.9%和25.9%。(2)各灾害发生频率高峰期各年代际不同,萌芽展叶期高温和开花坐果期高温低湿发生频率偏高,果实膨大期高温日灼最高,果实白熟期和成熟收获期连阴雨偏高。(3)每年至少3种灾害发生,4种灾害同年均发生频率达到41.4%,5种灾害同年均发生频率为10.3%。(4)各气象灾害影响权重不同,成熟收获期连阴雨影响最大,权重系数达到0.5848,其次是开花坐果期高温低湿,权重系数为0.1920,果期膨大期高温日灼和果实白熟期连阴雨位居第三和第四,分别为0.1081和0.0850,萌芽展叶期高温影响最小,权重系数仅为0.0301。对产量下降的5年进行气象灾害权重影响检验分析,结果与各灾害的权重特点基本一致。  相似文献   

19.
四川水稻不同生育阶段的干旱风险评估   总被引：2，自引：0，他引：2  
水稻是四川最主要的粮食作物,而干旱是制约水稻生产的主要因素,四川省春旱、夏旱和伏旱灾害频发,常导致水稻减产。本研究基于气象资料、水稻灾情史料和生育期资料,选取湿润指数距平率作为水稻干旱指标,构建了四川水稻干旱等级,并利用灾情样本进行了验证。在此基础上,分析了1961-2015年四川水稻不同种植区不同生育阶段的干旱时空变化特征及风险分布状况。结果表明:从时间变化看,近55年来,水稻移栽～孕穗期干旱总站数平均每10年增多0.56个,其中轻旱和重旱平均每10年分别增多0.20个和0.41个,而中旱基本不变;孕穗～开花期干旱总站数平均每10年减少0.49个,其中中旱和重旱平均每10年均减少0.22个,而轻旱基本不变;开花～成熟期干旱总站数平均每10年增多0.54个,其中轻旱和重旱平均每10年分别增多0.23个和0.55个,而中旱基本不变。干旱频率的分布特征为:移栽～孕穗期的干旱频率呈现中部高、西南部和东北部低的特征,高发区主要分布在北部的绵阳-南部的宜宾一线(36%～58.2%);孕穗～开花期的干旱频率由西向东递增,高发区主要分布在盆地北部和东北部(36%～61.9%);开花～成熟期的干旱频率呈由西向东递增的趋势,高发区主要分布在盆地东北部和盆南的局部地区(30%～47.3%)。水稻干旱风险分布为:移栽～孕穗期较高风险区和高风险区主要集中在德阳、资阳和宜宾等地;孕穗～开花期较高风险区和高风险区主要在盆地中部和东北部;开花～成熟期较高风险区和高风险区主要在盆地东北部和盆南的局部地区。  相似文献   

20.
作者就褐稻虱在水稻扬花后对米粒灌浆的影响进行定量研究。结果表明,米粒干物质的累积量与扬花后的天数呈极显著的logistic曲线关系。干物质积累总量、起始增长势、干物质积累旺盛期以及最大日增量均与褐稻虱虫量呈极显著的负相关。仅占籽粒充实总日数38.6％的灌浆盛期中,积累的干物质重为成熟时籽粒干重的65.84％,这是决定稻谷千粒重的关键时期。在孕穗末期到齐穗后的20d内,应尽可能地将褐稻虱种群控制到最低水平,孕穗末期在使用高活性药剂扑虱灵、吡虫啉时,用药有效剂量需确保控制效果30～35d,可获得最大的经济效益。  相似文献   

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