Evaluating susceptibility of almonds to anthracnose disease caused byCollectotrichum gloeosporioides

Susceptibility of almond fruit(Prunus dulcis (Mill.) Webb.) to anthracnose caused byColletotrichum gloeosporioides Penz.(=Gloeosporium amygdalinum Brizi) was investigated. Fruits were punctured, and a drop of spore suspension of the desired size and density was placed on the wound. Fruits were placed in a humid chamber for one week at 22°C. The diameter of the lesion of the infected fruits was used as an indicator of susceptibility. Disease development was found to be negatively correlated with the age of the fruit. The inoculation concentrations used in this research have no effect on the disease development, although the volume of the drop affected the size of the lesion to some extent. With constant, high relative humidity (saturation), the diameter of the anthracnose lesion increased by 1 mm per day, while under dry room conditions the increase was less than 0.5 mm per day. At 22°C lesions developed faster than at either 15° or 27°C. A detailed procedure for assessing sensitivity of fruit to anthracnose is described. This should enable improved comparison of susceptibility between genotypes and in different environments.     

Pre-harvest silk treatment with Trichoderma harzianum reduces aflatoxin contamination in sweetcorn

Journal of Plant Diseases and Protection - One of the most promising management tools to reduce mycotoxins in food and feed is the pre-harvest biological control of mycotoxigenic fungi using...     

Relationships among resistances to fusarium and Aspergillus ear rots and contamination by fumonisin and aflatoxin in maize

ABSTRACT Fusarium verticillioides, F. proliferatum, and Aspergillus flavus cause ear rots of maize and contaminate the grain with mycotoxins (fumonisin or aflatoxin). The objective of this study was to investigate the relationships between resistance to Fusarium and Aspergillus ear rots and fumonisin and aflatoxin contamination. Based on a previous study of 143 recombinant inbred lines from the cross NC300 x B104, 24 lines with the highest and 24 lines with the lowest mean fumonisin concentration were selected for further evaluation. Paired plots of each line were inoculated with F. verticillioides and F. proliferatum or with A. flavus in replicated trials in 2004 and 2005 in Clayton, NC, and College Station, TX. The low-fumonisin group had significantly lower levels of fumonisin, aflatoxin, and Fusarium and Aspergillus ear rots. Across year-location environments, all four traits were significantly correlated; the genotypic correlation (r(G)) ranged from r(G) = 0.88 (aflatoxin and Aspergillus ear rot) to r(G) = 0.99 (Fusarium and Aspergillus ear rots). Quantitative trait loci (QTLs) were identified and their effects estimated. Two QTLs affected both toxin concentrations, one QTL affected both ear rots, and one QTL affected Aspergillus and Fusarium rots and fumonisin. These results suggest that at least some of the genes involved in resistance to ear rots and mycotoxin contamination are identical or genetically linked.     

我国果实种子类中药材黄曲霉毒素污染状况及防控策略研究进展

以果实种子入药的中药材由于富含淀粉、多糖、脂肪和蛋白质等营养物质, 很容易受到黄曲霉毒素(aflatoxins, AFs)的污染。本文总结了近20年以来果实种子类药材有关AFs污染的研究报道, 汇总了5个国家和地区关于AFs的限量标准。通过CNKI数据库共检索到54篇报道AFs污染果实种子类药材的文献, 涉及药材48种, 污染药材数量呈现逐年增长的趋势, 其中薏苡仁、柏子仁、酸枣仁报道超过10次, 报道6~9次的7种药材中, 莲子中AFB1最高检出量超过药典限量的260倍以上。桃仁、槟榔、酸枣仁和大枣在2个国家和地区药典中有限量规定, 莲子、肉豆蔻和胡椒在3个国家和地区药典中有限量规定, 在国际贸易中需重点关注。另外, 通过对产毒素真菌生长、产毒素适宜环境因子及不同药材污染特征的分析, 针对中药材生产特点, 从采收、加工、贮藏三个环节提出了AFs污染防控措施的建议, 旨在为减少毒素污染、保障中药安全和产业健康发展提供参考。     

Phytophthora crown rot of almonds in Australia 1

Phytophthora crown rot, caused primarily by Phytophthora cambivora, has caused considerable losses in almond orchards in the Willunga and northern plains areas approximately 50 km north and south of Adelaide (AU), respectively. Other Phytophthora species including P. citrophthora, P. cryptogea, P. megasperma and P. syringae have also been associated with diseased trees. Tree losses have been associated with P. cactorum isolated from trunk cankers on scaffold limbs on trees in the Riverland almond-growing area approximately 350 km north-east of Adelaide. The Al mating type of P. cambivora was the most pathogenic to almond seedlings. Cvs Mission and Chellaston, which are commonly used as rootstocks, were highly susceptible to crown rot whereas peach cv. Nemaguard was resistant. An excised twig assay has been developed to screen micropropagated shoots for resistance to P. cambivora. Metalaxyl applied at 5 g active substance per tree in spring, winter and autumn in a shallow trench close to the trunk prevented the development of trunk cankers. Foliar sprays of phosphonate (H₃PO₃) at 2 g active substance per litre in autumn and spring also inhibited canker development.     

Spatial distribution of Aspergillus flavus and its toxigenic strains on commercial cottonseed from south Texas and its relationship to aflatoxin contamination

The structure of Aspergillus flavus communities associated with south Texas cottonseed was determined by analysing samples from 178 truckloads of commercial cottonseed from 35 gins, extending from Fort Bend County in the north to the Rio Grande Valley in the south, from September 1999 to October 2001. The number of colony-forming units (CFU) of A. flavus on the cottonseed, and the percentage of S strain (%S) were both correlated with aflatoxin contamination of cottonseed. The number of CFU differed between both regions and seasons, while %S differed only between regions. Comparison of maps of CFU and %S revealed that CFU shows a higher variation across years, while %S shows higher spatial variation. The Rio Grande Valley had significantly lower CFU and %S strain than the Coastal Bend and Upper Coast regions. Cottonseed produced in 1999 had significantly more A. flavus than that produced in either 2000 or 2001. Identification of factors dictating geographical variation in S-strain incidence may provide insights that will lead to improved aflatoxin management.     

1972-2013年新疆玛纳斯河流域冰川变化

利用多期遥感资料,分析了新疆玛纳斯河流域1972-2013年的冰川变化,并对其原因进行了分析.结果表明:1972-2013年冰川共退缩了159.02 km2(变化率为-24.61％),海拔3 800～4200 m之间退缩最为强烈,冰川末端海拔升高明显(41 a间海拔3 200～3300m之间的冰川消失).冰川变化存在一定的区域差异性,玛纳斯河主源冰川退缩速度最快,左岸次之,右岸退缩速度最慢.从朝向上看,各个朝向的冰川均处于退缩状态,偏东向的冰川退缩面积明显大于其他方向.近40 a,流域冰川总储量减少了59.09～85.94 km3.与中国天山其他地区冰川相比,该流域的冰川退速率较高,气温升高是该区域冰川退缩的主要原因.     

2000-2009年乌鲁木齐市湿沉降变化特征

根据乌鲁木齐市2000-2009年酸沉降观测资料,分析主要控制指标的特征变化。结果表明：乌鲁木齐市的湿沉降污染严重,除氮湿沉降为1.06 g·m^-2,与全国平均水平基本持平外;硫湿沉降为3.21 g·m^-2、钙湿沉降为3.22 g·m^-2,均高于其他省市。硫湿沉降主要源于本地SO₂的排放,近年来又有加重的态势;而氮沉降对湿沉降的贡献有增强趋势,同时钙湿沉降的降低有可能导致湿沉降酸化的加剧。     

1999-2007年祁连山区植被指数时空变化

基于SPOTVGT-NDVI数据,结合累积平均法、均值法、趋势线分析和影像差异法,分析了祁连山地区植被时空变化。结果表明:祁连山区植被覆盖东多西少;1999年以来植被呈增加趋势,植被指数(NDVI)增速为1.1%/10a,东段增速(1.6%/10a)大于中段(1.4%/10a)和西段(0.6%/10a);NDVI年内月和旬变化曲线均呈单峰型,7～8月达到最大。7～8月雨热达到最佳,适宜植物的生长;而从10月到翌年2月祁连山草地处于枯黄期;3～4月草地处于返青期,植物生长缓慢,NDVI都较低。祁连山NDVI增加和减少的面积分别占总面积的37.39%和10.95%。植被覆盖增加的地区主要分布在高山和亚高山森林草地,东段、中段、西段NDVI最大增加量分别为0.15,0.21和0.12。植被覆盖减少的地区主要分布在河流河谷以及青海湖周边,东段、中段、西段NDVI最大减少量分别为0.19,0.28和0.17。     

陕西关中地区杀虫剂清园措施对桃树桃蚜种群的影响

在田间条件下研究了陕西关中地区5种杀虫剂在不同时间进行清园处理对桃树桃蚜种群的影响。结果表明,两次施药对桃蚜种群的增长均有较好的控制效果,尤以第1次施药后45d内和第2次施药后30d内,即5月6日前控制效果明显。但5月6日以后,各药剂处理的控制效果均明显下降,至第1次施药后的第60天和第2次施药后第45天,有的药剂处理已经完全失去了控制效果。早春清园对桃蚜种群的早期增长有较好的防治效果,但此时桃蚜种群数量总体偏低,直接危害并不严重,从减少用药次数和用药量的角度,早春清园预防桃蚜有无必要值得进一步试验研究。     

Role of phenology in host susceptibility and within-plant spread of stem rust during reproductive development of perennial ryegrass

ABSTRACT Perennial ryegrass (Lolium perenne) was inoculated with urediniospores of Puccinia graminis subsp. graminicola at four stages of reproductive tiller development. All developmental stages, from expansion of the penultimate leaf through anthesis, were equally susceptible to infection measured as number of pustules per total inoculated plant area. However, within each stage from boot through anthesis, there was a negative correlation of susceptibility with age of host tissue, the highest disease severities occurring on expanding or newly expanded leaves or inflorescences. Within-plant spread of the disease from primary lesions on the flag leaf sheath to the elongating stem of the inflorescence was observed and verified. A single primary infection on the leaf sheath can produce an elongated strip of contiguous secondary infections on the inflorescence head and stem, which is a characteristic sign of stem rust. Position and timing of eruption of the secondary pustules on the stem can be explained by assuming that infections occur on the stem slightly distal to the overlying sheath lesion and erupt one latent period later, by which time tiller elongation has moved the stem infection site upward. Repeated infections occur as the stem elongates, producing contiguous lesions. Expansion rate and final lesion area on the stem were correlated with elongation rate of the inflorescence. Microscopic observation of plant tissue sections revealed that the fungus sporulates on the inner surface of the sheath, and germinating urediniospores are attached to the stem surface under the covering sheath starting 1 to 2 cm distal to the location of the sheath infection site.     

1956-2008年辽宁省日照时数变化特征

根据辽宁省7市1县8个气象站近53年(1956-2008年)逐月日照时数资料,建立辽宁省月、年日照时数时间序列,运用复值Morlet小波分析、5年滑动、气候倾向率和Mann-Kendall趋势检验法,分析辽宁省近53年的日照时数变化特征.结果表明:年日照时数呈显著减少趋势,倾向率为-57.61h/10a,M(标准化变量)值为-6.49,且存在25年和16年左右的周期性变化;春、夏、秋、冬四季的日照时数均表现为下降趋势,夏季下降趋势最明显,冬季表现最微弱,倾向率分别为-18.345h/10a和-7.615h/10a;年代际的变化趋势是,2000年以后日照时数的下降趋势很显著,M值为-2.59,而日照时数高值区和低值区的范围都有所减小.     

Factors associated with the incidence of Aspergillus section Flavi and aflatoxin contamination of peanuts in the Busia and Homa bay districts of western Kenya

The aim of this study was to identify agronomic, ecological and sociocultural factors that could be modified to reduce the risk of aflatoxin contamination of peanuts from western Kenya. Presence of fungi within section Flavi of the genus Aspergillus and levels of total aflatoxin were determined for 436 peanut samples from the Busia and Homa bay districts. A total of 1458 cultures of Aspergillus flavus or A. parasiticus isolated from the samples were assayed for production of aflatoxin B₁, B₂, G₁ and G₂. Associations among the incidences of fungal species, incidences of samples with ≥10 μg kg^?1 aflatoxin, production of specific aflatoxin types and various agronomic, ecological and sociocultural factors were modelled with chi‐squared and logistic regression methods. The predominant species were A. flavus L‐strain (78% incidence), A. flavus S‐strain (68%) and A. niger (65%). Occurrence of A. caelatus, A. alliaceus and A. tamarii in Kenya was also documented. Samples from the Busia district were three times (odds ratio = 3·01) as likely to contain ≥10 μg kg^?1 of total aflatoxin as were samples from the Homa bay district, while samples containing A. flavus S‐strain were 96% more likely to exceed this threshold compared with samples from which this fungus was not isolated. Grading, planting improved cultivars and membership of a producer marketing group were negatively associated with the incidence of A. flavus, while crop rotation was negatively correlated with the incidence of B aflatoxins. These sociocultural factors can be modified to reduce the risk of peanut contamination with aflatoxin.     

公元1400年以来陇中地区干旱灾害特征

通过对历史文献资料的整理与统计分析,对甘肃陇中公元1400-1999年干旱灾害的等级序列特征、年代际变化、季节变化、空间变化及气候背景进行研究.结果表明:陇中公元1400-1999年共发生旱灾280次,平均每2.14年发生1次.干旱灾害以中度旱灾为主,占旱灾总次数的45.4%,其次是大旱灾,占旱灾总次数的32.1%,特...     

1982-2006年华北植被指数时空变化特征

利用1982-2006年GIMMS/NDVI数据,研究华北近25 a来植被指数在时间和空间上的变化。结果表明:①植被指数的年内变化呈单峰型,最大值出现在夏季,其中北京市NDVI最大,森林NDVI比农田和草地NDVI大;②华北年平均NDVI呈增加趋势,河北省植被指数增加最快,北京市次之,不同土地覆盖类型中,农田NDVI增加最快,草地次之,森林最小;③空间趋势分析结果显示,华北植被指数改善的面积占整个地区面积的15.96%,退化面积占11.86%,其中,河北省改善面积最大,内蒙古退化较明显,不同土地覆盖类型中,农田植被改善最明显;④基于华北近年暖干化发展趋势下,人类活动对该区域NDVI变化起到了重要作用。     

1961-2010年河北省日照变化分析

利用EOF、最大熵谱分析、Lepage突变性检验等方法,分析河北省1961-2010年日照时数的变化情况。结果表明：河北省日照时数空间分布差异较大,整体上表现为由北向南呈递减趋势,各区日照时数普遍呈下降趋势,其中中南大部地区下降趋势较为明显,而北部地区日照时数下降趋势相对较小,年日照时数下降趋势异常显著;空间分布上既有“一致型”,也存在“南中北型”;从时间变化上看,除个别月份外,其他年、季、月日照时数下降趋势均异常显著;Lepage突变性分析结果显示,在1972年和2001年有较为显著的突变现象发生。分析结果还显示,河北省年日照时数具有非常明显的年际变化特征,4.2 a左右的年际变化周期比较明显。影响河北省日照时数减少的主要因子有云量和雾,浮尘并不是引起河北省日照时数下降的主要原因。     

乌鲁木齐市采暖期大气PM2.5 特征分析

利用扫描电镜-X射线能谱仪(SEM-EDX)、离子色谱、电感耦合等离子发射光谱和全自动化学分析仪器对乌鲁木齐市采暖期大气细颗粒物(PM2.5)的形态结构及水溶性无机离子特征进行分析.结果表明:①乌鲁木齐市不同功能区大气PM2.5类型多样,主要类型有硅铝酸盐、硅铝飞灰、铁氧化物颗粒、硫酸/碳酸盐晶体、钛聚集颗粒物、碳质气溶胶(烟尘集合体、焦油球、不规则碳质颗粒)、富氟颗粒和不明物质等,其中硅铝酸盐、硅铝飞灰、烟尘集合体在各个功能区都观测到,富氟颗粒仅存在于头屯河区、天山区和水磨沟区;②SO42-、NH4+、NO3-、Cl-为乌鲁木齐市水溶性无机离子的主要组成部分,占全部无机离子的90.3％;③乌鲁木齐市大气PM2.5的pH在3.72 ～5.76之间,平均值为5.11,其大气气溶胶整体偏酸性,其中[NO3-]与[SO42-]的比值小于1,可认为固定源排放是乌鲁木齐市大气PM2.5中水溶性无机离子的主要来源.