Fungal volatiles associated with moldy grain in ventilated and non-ventilated bin-stored wheat

The fungal odor compounds 3-methyl-l-butanol, l-octen-3-ol and 3-octanone were monitored in nine experimental bins in Winnipeg, Manitoba containing a hard red spring wheat during the autumn, winter and summer seasons of 1984–85. Quality changes were associated with seed-borne microflora and moisture content in both ventilated and non-ventilated bins containing wheat of 15.6 and 18.2% initial moisture content. All three odor compounds occurred in considerably greater amounts in bulk wheat in non-ventilated than in ventilated bins, particularly in those with wheat having 18.2% moisture content. The presence of these compounds usually coincided with infection of the seeds by the fungi Alternaria alternata (Fr.) Keissler, Aspergillus repens DeBarry, A. versicolor (Vuill.) Tiraboschi, Penicillium crustosum Thom, P. oxalicum Currie and Thom, P. aurantiogriseum Dierckx, and P. citrinum Thom. High production of all three odor compounds in damp wheat stored in non-ventilated bins was associated with heavy fungal infection of the seeds and reduction in seed germinability. High initial moisture content of the harvested grain accelerated the production of all three fungal volatiles in non-ventilated bins.     

Analysis of Microdochium nivale isolates from wheat in the UK during 1993

A total of 144 isolates of Microdochium nivale from stem bases of winter wheat were taken from 30 sites and 91 isolates from grain were taken from seven sites throughout the UK. Identification by polymerase chain reaction (PCR) amplification of the internal transcribed spacer (ITS) region followed by restriction enzyme digestion of the PCR product revealed that 70% of stem base isolates were M. nivale var. majus and 30% var. nivale while 93% grain isolates were var. majus and 7% var. nivale. Almost all isolates were resistant to the benzimidazole fungicide benomyl. Perithecial production in vitro was more common in var. majus isolates and occurred in almost all grain isolates, but was less common in stem base isolates. The implications of the findings in terms of epidemiology and chemical control of this important cereal pathogen are discussed.     

Biodelignification of wheat straw by different fungal associations

Seven strains of fungi were tested individually as well as in different combinations to determine their lignin degrading ability using wheat straw as natural substrate. When tested individuallyPhanerochaete chrysosporium caused a maximum loss in total organic matter (26.45%) as well as in the lignin component (28.93%). The associations between different groups: white-rot plus white-rot, white-rot plus brown-rot and white-rot plus soft-rot fungi revealed that in certain combinations the ligninolysis was enhanced to variable extent.Deadalea flavida plusP. chrysosporium was the best association to bring about a lignin loss of 36.27%.     

灰翅麦茎蜂的生物学及其防治对策

针对近年来在青海省和甘肃省春小麦生产中灰翅麦茎蜂CephusfumpennisEversmann的危害造成春小麦千粒重下降 8～ 1 0g,严重减产 ,籽粒品质变差 ,麦秆失去使用价值等问题 ,介绍了麦茎蜂的分布、主要生物学特征 (形态特征和生活习性等 )和目前的主要防治对策 ,包括耕作措施 (深翻、轮作倒茬 )、药剂、生物防治及选育抗虫小麦新品种     

In vitro degradation of wheat straw by anaerobic fungi from small ruminants

Abstract

Anaerobic ruminal fungi may play an active role in fibre degradation as evidenced by the production of different fibrolytic enzymes in culture filtrate. In the present study, 16 anaerobic fungal strains were isolated from ruminal and faecal samples of sheep and goats. Based on their morphological characteristics they were identified as species of Anaeromyces, Orpinomyces, Piromyces and Neocallimastix. Isolated Neocallimastix sp. from goat rumen showed a maximum activity of CMCase (47.9 mIU ml^?1) and filter paper cellulase (48.3 mIU ml^?1), while Anaeromyces sp. from sheep rumen showed a maximum xylanolytic activity (48.3 mIU ml^?1). The cellobiase activity for all the isolates ranged from 178.0 – 182.7 mIU ml^?1. Based on the enzymatic activities, isolated Anaeromyces sp. from sheep rumen and Neocallimastix sp. from goat rumen were selected for their potential of in vitro fibre degradation. The highest in vitro digestibility of NDF (23.2%) and DM (34.4%) was shown for Neocallimastix sp. from goat rumen, as compared to the digestibility of NDF and DM in the control group of 17.5 and 25.0%, respectively.     

Fungal communities and health status of roots of winter wheat cultivated after oats and oats mixed with other crops

Health status of winter wheat roots and thecomposition of wheat root fungi were studiedover 1996-1999 following the cultivation ofoats in a pure stand and mixed with otherplants as forecrops. The infection of wheatroots by >Gaeumannomyces graminis wasobserved to be largely dependent on the kind offorecrop; the best being oats in a pure stand,and then oats with pea or lupin mixtures. Inthe emergence and shooting phases, saprophyticfungi were dominant, while in the stage of harddough stage mainly pathogenic fungi, especially>G. graminis were common. The pathogenicfungi were mostly represented by >G.graminis and >Fusarium spp., while >Rhizoctonia spp. were much less frequent.The composition of the fungal communitydepended considerably on the forecrop anddevelopment phase of the plant. The kind offorecrop significantly affected the frequencyof infection by >G. graminis. The highestnumber of isolates was obtained from wheat rootsof crops grown after a mixture of oats andbarley.     

施氮量及底追比例对小麦产量、土壤硝态氮含量和氮平衡的影响

研究了高产麦田中施氮量和底追比例对冬小麦籽粒产量、土壤硝态氮含量和氮素平衡的影响。田间试验在山东省龙口市中村进行,试验区小麦各生育阶段的降雨量和零度以上的积温分别为:82.9mm,649.8℃(播种~冬前)、33.3mm,578.7℃(冬前~拔节)2、8mm,359℃(拔节~开花)、84.3mm,837.6℃(开花~成熟)。试验设3个施氮量:0kg.hm-2(CK)、168kg.hm-2(A)、240kg.hm-2(B);在施氮量168kg.hm-2和240kg.hm-2条件下分别设3个底追比例:1/2∶1/2(A1和B1)、1/3∶2/3(A2和B2)、0∶1(A3和B3)。结果表明:不同施氮处理之间植株氮积累量无显著差异;与不施氮处理相比,施氮可显著提高籽粒产量和蛋白质含量,施氮量为168kg.hm-2、底追比例为1/3∶2/3的处理A2与处理B2、B3差异不显著,但处理A2显著提高了氮肥利用率,降低了土壤残留量和氮素表观损失量;施氮量相同,适当增加追施氮肥的比例可显著提高籽粒产量、蛋白质含量和氮肥利用率。试验还表明,在拔节期,底施氮量为84kg.hm-2和120kg.hm-2的处理A1、B1,在80~100cm和100~160cm土层分别出现硝态氮的累积;而底施氮量为56kg.hm-2的处理A2,在0~200cm土层硝态氮含量和累积量与不施氮处理无显著差异。在成熟期,追施氮量大于160kg.hm-2的处理B3、A3和B2,硝态氮在120~180cm土层出现累积高峰,已下移到小麦根系可吸收范围之外,易于造成淋溶损失;而追氮量为112kg.hm-2的处理A2,在100~200cm土层硝态氮累积量与对照无显著差异。试验中,施氮量为168kg.hm-2底追比例为1/3∶2/3的处理A2的籽粒产量、蛋白质含量、地上部植株氮肥吸收利用率、氮肥农学利用率和籽粒氮肥吸收利用率均较高,100~200cm土层未出现硝态氮的明显累积,氮素表观损失量最少,为最佳氮肥运筹方式。     

Effects of mycorrhizal infection on drought tolerance and recovery in safflower and wheat

The influence of arbuscular mycorrhizal fungi on drought tolerance and recovery was studied in safflower (Carthamus tinctorius L.) and wheat (Triticum aestivum L.). Plants were grown with and without the mycorrhizal fungus, Glomus etunicatum Becker & Gerd., in nutrient-amended soil under environmentally-controlled conditions to yield mycorrhizal and nonmycorrhizal with similar leaf areas, root length densities, dry weights, and adequate tissue phosphorus. When drought stress was induced, mycorrhizal infection did not affect changes in leaf water, osmotic or pressure potentials, or osmotic potentials of leaf tissue rehydrated to full turgor in either safflower or wheat. Furthermore, in safflower, infection had little effect on drought tolerance as indicated by the level of leaf necrosis. Mycorrhizal wheat plants, however, had less necrotic leaf tissue than uninfected plants at moderate levels of drought stress (but not at severe levels) probably due to enhanced phosphorus nutrition. To determine the effects of infection on drought recovery, plants were rewatered at a range of soil water potentials from –1 to –4 MPa. We found that although safflower tended to recover more slowly from drought after rewatering than wheat, mycorrhizal infection did not directly affect drought recovery in either plant species. Daily water use after rewatering was reduced and was correlated to the extent that leaves were damaged by drought stress in both plant species, but was not directly influenced by the mycorrhizal status of the plants.     

吸虫塔诱捕的昆虫种类及对麦蚜的监测效果研究

在河南省原阳县河南省农科院试验基地安装了吸虫塔(suction trap),2009-2010连续2年在该地区进行了昆虫诱捕及麦蚜监测,并对诱捕到的麦蚜数量动态,以及吸虫塔和黄色粘板监测的比较进行了分析。结果显示:该吸虫塔对多种小型昆虫有很好的诱捕效果,在2009年和2010年分别诱捕到了8目39科58种和8目37科61种的小型昆虫,数量较多的主要集中在双翅目、半翅目、膜翅目等。该吸虫塔对麦蚜起到了很好的监测效果,2009年麦蚜始见期比2010年早,2009年麦蚜的优势种为禾谷缢管蚜Rhopalosiphum padi(L.),2010年是荻草谷网蚜Sitobion miscanthi(Takahashi),2009年麦蚜大量发生和高峰期出现的较早,禾谷缢管蚜分别在5月1日,5月13日,5月19日到达高峰,5月19日以后数量急剧减少;2010年麦蚜大量发生和高峰期出现的相对较晚,荻草谷网蚜在5月3日、5月7日、5月19日和5月31日出现4个高峰,5月31日以后蚜量才骤减。对白天不同时段诱捕的蚜量分析可知,麦蚜在早晨和傍晚飞翔活动相对较强。吸虫塔与黄色粘板监测的相关性分析表明,吸虫塔诱集麦蚜的数量动态与黄板诱集的数量动态趋势基本一致,吸虫塔诱蚜量与黄板蚜量具有较好的相关性,但吸虫塔诱集麦蚜出现高峰期早于黄色粘板。     

Fungal density in the sands of the Mediterranean coast beaches

The fungal density of one hundred and forty-eight samples of sands obtained from forty-two Spanish Mediterranean littoral beaches are investigated. The CFU/g number ranged from 15 and 76×10⁵. The most commonly isolated genera were: Penicillium, Cladosporium, Aspergillus, Acremonium, Alternaria, Fusarium. The keratinophilic capacity of all the isolated fungal strains was also determined.     

Fungal remains from the Late Riphean

The paper describes organic remains of one billion years old from the Lakhanda microbiota of the Uchur-Maya Region of southeastern Siberia. The microfossils were discovered on organic sapropelic films. The preserved morphological characters and some developmental stages of the ancient organisms, which are fixed in fossil state, suggest that some of them resembled zygomycetes. Other microfossils under consideration are comparable to reproductive structures of myxomycetes in the type of fusion of spheroid cells and formation of various types of aggregation (sori). Colonies of unicellular microfossils that are arranged in a branching pseudomycelium superficially resemble yeasts. The presence in the same biota of fungal remains belonging to the Myxomycota and Mycota, as well as members of xanthophyte vaucherian algae, indicates that various branches of eukaryotes might have developed in parallel even earlier than the Late Riphean.     

Genetic research as the valid base of strategies for breeding rust resistant wheats

It is known that few wheat cultivars maintain their resistance to rust diseases for a long period of time, particularly when crop populations become genetically more uniform. A number of genetically diverse, so far unexploited, sources of rust resistance in the natural as well as mutagenized population of wheat cultivars were identified. Several of these genes were placed in agronomically superior well-adapted backgrounds so that they could be used as pre-breeding stocks for introducing genetic diversity for resistance in a crop population. Some of these stocks when employed as parents in several cross combinations in a breeding programme have generated a number of promising cultivars with diversity for resistance.Many presently grown wheats in India, near-isogenic lines each with Lr14b, Lr14ab, Lr30 and certain international cultivars were identified as possessing diverse sources of adult plant resistance (APR) to leaf rust. Prolonged leaf rust resistance in some of the Indian cultivars was attributed to the likely presence of Lr34 either alone or in combination with other APR components. Tests of allelism carried out in certain cultivars that continue to show adequate levels of field resistance confirm the presence of Lr34, which explains the role that this gene has played in imparting durability for resistance to leaf rust. Also, Lr34 in combination with other APR components increases the levels of resistance, which suggests that combination of certain APR components should be another important strategy for breeding cultivars conferring durable and adequate levels of resistance. A new adult plant leaf rust resistance source that seems to be associated with durability in Arjun has been postulated. Likewise, cultivars possessing Sr2 in combination with certain other specific genes have maintained resistance to stem rust.Further, non-specific resistances that were transferred across widely different genotypes into two of the popular Indian wheats provided easily usable materials to the national breeding programmes for imparting durable resistance to stripe rust.     

Rapid changes in pollen production in experimental outcrossing populations of wheat

For evolutionary reasons, pollen production is expected to be modified when changes occur in plant mating systems. In this study, outcrossing was enforced through male-sterility in usually autogamous populations of winter wheat. The correlated changes in pollen production were studied after a 6-year period of natural evolution. Both the disappearance of individuals with the lowest pollen production and the increase in the production of fertile pollen per spike were observed in male-fertile plants. The results are interpreted as a selection on male function. Some morphological differences also appeared in evolved populations between male-fertile and male-sterile plants. These differentiations are discussed in light of resource allocation theory.     

三类重要真菌生物活性物质及其研究方法概述

对高等真菌、内生真菌和海洋真菌活性物质的研究现状进行了概述,并对活性物质的筛选和分离方法等进行了介绍。     

小麦收割对新疆北部集约化棉区主要天敌昆虫种群数量的影响

于2009年6—8月小麦成熟至收割期对新疆北部奎屯垦区124团集约化棉区进行了调查,通过扫网法采集了棉区麦田和棉田的昆虫,并对其种群数量进行了统计分析。结果表明:随着小麦逐渐成熟,麦田中的天敌昆虫数量持续下降;当小麦全部收割后,麦田中只有极少数天敌昆虫生存。而与麦田相邻的棉田中的天敌昆虫数量在小麦收割后迅速上升,平均百网虫量达到59.23头,高于对照组连片棉田(平均百网虫量15.33头);小麦的收割比例与棉田天敌昆虫的种群数量存在显著正相关关系(P<0.05),4类主要天敌昆虫(草蛉科、姬蜂科、瓢虫科、食蚜蝇科)种群数量变化趋势之间没有显著差异。小麦收割会驱使失去生境的天敌昆虫转移进入相邻的棉田,姬蜂科、瓢虫科、食蚜蝇科等活动能力强的天敌昆虫类群更容易进入新的生境,而活动能力相对较弱的类群(草蛉科)则难以转移至棉田中。深入研究集约化棉区麦田与棉田中天敌昆虫的库源关系,将有助于集约化农业体系的进一步发展。     

Ecogeographical distribution of HMW glutenin alleles in populations of the wild tetraploid wheat Triticum turgidum var. dicoccoides

Summary Polymorphism of high molecular weight (HMW) glutenin subunits in 466 accessions of the wild tetraploid wheat Triticum turgidum var. dicoccoides in Israel was characterized with regard to the ecogeographical distribution of the HMW glutenin alleles, both between and within 22 populations, and along transects in a single population. While some populations were monomorphic for all the HMW glutenin loci, namely, Glu-A1-1, Glu-A1-2, Glu-B1-1 and Glu-B1-2, others contained up to four alleles per locus. Intrapopulation variability could be predicted by the geographical distribution: marginal populations tended to be more uniform than those at the center of distribution. The various HMW glutenin alleles tended to be clustered, both at a regional level and within a single population along transects of collection. It is suggested that this clustering is due to selection pressures acting both at a regional and at a microenvironmental level. This was confirmed by the significant correlations found between the MW of subunits encoded by Glu-A1-1 and the populations' altitude, average temperature and rainfall. The possible selective values of seed storage proteins are discussed.     

小麦体内生化物质在抗蚜中的作用

综述了小麦体内生化物质的抗蚜作用 ,主要包括不同抗性品种对麦蚜的影响、小麦体内氨基酸、糖类、酚类物质、生物碱和非蛋白氨基酸等与抗蚜性的关系 ,以及蚜虫对小麦体内抗虫生化物质的诱导作用 ,并提出了深入研究小麦生化物质与抗蚜性关系的前景和意义。     

QTL mapping for yield and yield contributing traits in two mapping populations of bread wheat

In bread wheat, single-locus and two-locus QTL analyses were conducted for seven yield and yield contributing traits using two different mapping populations (P I and P II). Single-locus QTL analyses involved composite interval mapping (CIM) for individual traits and multiple-trait composite interval mapping (MCIM) for correlated yield traits to detect the pleiotropic QTLs. Two-locus analyses were conducted to detect main effect QTLs (M-QTLs), epistatic QTLs (E-QTLs) and QTL × environment interactions (QE and QQE). Only a solitary QTL for spikelets per spike was common between the above two populations. HomoeoQTLs were also detected, suggesting the presence of triplicate QTLs in bread wheat. Relatively fewer QTLs were detected in P I than in P II. This may be partly due to low density of marker loci on P I framework map (173) than in P II (521) and partly due to more divergent parents used for developing P II. Six QTLs were important which were pleiotropic/coincident involving more than one trait and were also consistent over environments. These QTLs could be utilized efficiently for marker assisted selection (MAS).     

Ecotoxicological aspects of Aspergilli present in the phylloplane of stored leaves of chewing tobacco (Nicotiana tobaccum)

Nine different species of Aspergillus were isolated from the phylloplane of stored chewing tobacco (Nicotiana tobaccum) of different ages. The maximum number of species were isolated from 12 and 18 month old leaves. A. ruber, A. ochraceus, A. flavus and A. nidulans were usually associated with older leaves while A. niger, A. fumigatus and A. flavus were isolated from 6 month old leaves. Approximately 18% of Aspergilli were found to be mycotoxigenic. Sterigmatocystin was produced by three different species. A. ochraceus produced patulin and ochratoxin. All aflatoxigenic strains of A. flavus produced aflatoxin B1 but none of the isolates of A. flavus produced aflatoxin G2. The percentage of toxigenic isolates of different species varied considerably.