Germination requirements for 29 terrestrial and wetland wild plant species appropriate for phytotoxicity testing

BACKGROUND: Species selected for phytotoxicity testing have been limited to a few standard crop species owing to restrictive recommendations at the regulatory level. However, guidelines by the Organisation for Economic Development and Cooperation (OECD) were recently amended in 2006 to include a list of herbaceous non‐crop plant species suitable for testing. The objective of this study was to outline the optimum germination requirements for a selection of wild species for which seeds were readily available from commercial suppliers. RESULTS: Of the 29 herbaceous terrestrial and wetland species included in this study, all achieved 50% germination and 23 reached > 70% germination to meet the criterion outlined in the OECD guidelines. Most species attained their maximum germination within 14 days or less. Cold stratification of imbibed seeds improved germination for 14 species. Increasing sowing soil depth did not improve seed germination. The variance attained in this experiment between replicates was low, especially for species with > 70% germination (standard error ～5%). CONCLUSION: The present study showed that 23 of the 29 species tested required minimal pretreatments and produced consistent, reliable and uniform germination reaching at least 70%. The inclusion of wild plant species in regulatory testing should be given real consideration. Copyright © 2008 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

出芽短梗霉菌菌株PA-2的除草活性及对作物的安全性

从青海省平安县发病杨树叶片上分离得到菌株 PA-2,其发酵滤液对多种阔叶杂草表现出较好的除草活性。对该菌株的培养特征和16S rDNA基因序列分析后,确定其为短梗霉属出芽短梗霉菌Aureobasidium pullulans。盆栽试验表明,其发酵滤液对供试阔叶杂草猪殃殃、藜、冬葵、酸模叶蓼及禾本科野燕麦的鲜重防效分别达到87.25%、78.46%、82.25%、62.11%、80.27%。作物安全性试验结果表明,其发酵滤液对小麦、蚕豆、青稞很安全,对油菜、豌豆有轻微影响。综上所述,菌株 PA-2具有作为微生物除草剂的开发潜力。     

灯盏花大田杂草种类调查及防除

经过4年对灯盏花田杂草种类的调查确定,在云南玉溪地区灯盏花田常见杂草有32种,隶属16科,主要杂草是鹅肠菜、野燕麦、长芒棒头草、无芒稗、酸模叶蓼,6月下旬至7月初为发生第1高峰期,10月中至11月下旬为发生第2高峰期,可通过药剂土壤处理、药剂茎叶喷雾防治和人工拔除控制灯盏花田杂草。     

江苏省镇江市麦田杂草发生情况调查

为了摸清江苏省镇江市麦田杂草种类、分布状况、出草规律、草相变化、防除情况等,通过倒"W"形九点取样法对镇江市麦田杂草进行了调查。调查结果显示镇江市麦田杂草有29科99种,日本看麦娘、菵草、猪殃殃、看麦娘、稻槎菜、硬草、繁缕、大巢菜、荠菜、涩荠、野老鹳草、牛繁缕、早熟禾为该地区主要危害性杂草,其中菵草、日本看麦娘、猪殃殃为麦田杂草群落优势种。不同地形区域杂草种类和优势种不同。镇江市麦田杂草由20世纪90年代初以看麦娘、日本看麦娘和猪殃殃等为主演变为以菵草、日本看麦娘、猪殃殃为主,稻槎菜、硬草、繁缕等发生较重。出草高峰集中在小麦播后15 d左右,具体到镇江来说11月底至12月上旬为杂草发生高峰期。针对镇江本地杂草发生情况,制定了以土壤封闭和茎叶处理相结合的防控技术方案。     

小麦幼苗及其次生代谢产物丁布对杂草的异株克生活性

研究了小麦活体、小麦水提液及小麦次生代谢产物丁布对几种杂草的异株克生活性。小麦与马唐、反枝苋、野燕麦、早熟禾、稗草等杂草混播的盆栽试验呈现出小麦播种密度越大,杂草种子萌发率越低的趋势。小麦水提液对马唐、反枝苋、早熟禾、稗草、野燕麦根和茎的生长均有明显的异株克生作用,IC₅₀(根)<1.5 mg/mL,IC₅₀(茎)<3.0 mg/mL,而对黑麦草、圆叶牵牛无明显的抑制活性。除马唐外,小麦水提液对供试杂草种子萌发抑制效果不明显。小麦次生代谢产物丁布对3种不同杂草的根、茎总体抑制效果为反枝苋>马唐>野燕麦,IC₅₀(根、茎)<1.5mg/mL,IC₅₀(种子萌发)<3.5 mg/mL。比较IC₅₀可知,生物活性:丁布>小麦水提液。丁布是小麦中具有异株克生活性的次生代谢物。     

Predicting the growth and competitive effects of annual weeds in wheat

The growth and competitiveness of 12 annual weed species were studied in crops of winter wheat, in which weeds were sown to give a wide range of plant densities. Weed growth patterns were identified; early species which senesced in mid-summer were less competitive than those with a growth pattern similar to that of the crop. Most species had little effect on crop yield in 1987, and this was attributed to a high crop den sity. Crop yield-weed density relationships for all species in 1988 and for Galium aparine in 1987 were well described by a rectangular hyperbola. Species were listed in the following competitive order based on the percentage yield loss per weed m^?2: Avena fatua > Matricaria perforata > Galium aparine > Myosotis arvenis > Poa trivialis > Alopecurus myosuroides > Stellaria media > Papaver rhoeas > Lamiumpur-pureum > Veronica persica > Veronica hederi-folia > Viola arvensis. Prediction of yield loss is discussed. The assumptions inherent in using Crop Equivalents (based on relative weights of weed and crop plants), are challenged; with intense competition, weed biomass at harvest failed to replace lost crop biomass, and harvest index was reduced. It is concluded that a competi tive index, derived from yield density relation ships, and expressed as the percentage yield loss per weed m^?2, is more likely to reflect the com petitive ability of a species than an index obtained from plant weights in the growing crop.     

Weed seedling emergence and seed survival: separating the effects of seed position and soil modification by tillage

Tillage causes both vertical redistribution of weed seeds and changes in soil physical properties. These two factors are rarely distinguished in studies of the impact of tillage on seedling emergence or seed survival. In this study, seeds of Chenopodium album L., Amaranthus retroflexus L., and Abutilon theophrasti Medik, were planted at particular depths in pots of undisturbed or stirred soil to separate these effects. Emergence and survival data were analysed by non-linear regression to determine the nature of significant differences between treatments. Emergence increased with slight burial and then decreased exponentially at greater depths. Average emergence over all depths was generally greater in tilled sou than in unfilled soil, particularly for C. album and A. retroflexus . Seed survival approached a maximum with increasing depth. Average survival of seeds that did not produce emerged seedlings was greater in tilled soil than in untilled soil for C. album and A. retroflexus . Thus, tillage affects emergence and seed survival of weeds through changes in soil conditions independently of effects resulting from redistribution of seeds in the soil profile.     

THE EFFECT OF DEPTH OF BURYING AND FREQUENCY OF CULTIVATION ON SURVIVAL AND GERMINATION OF SEEDS OF WILD OATS (AVENA FATUA L. AND AVENA LUDOVICIANA DUR.)

Summary. Seeds of Avena fatua and A. ludoviciana were sown at a depth of 15 cm or mixed into the top 5 cm of soil in small field-plots at Rothamsted and subjected to 5 different regimes of depth and frequency of cultivation for 3 years, after which all plots were dug to 15 cm in spring and autumn for a further 4 years. Seedlings were counted and no plants were allowed to produce seeds. After 7 years, soil-samples showed that very few intact seeds of A. fatua and none of A. ludoviciana remained, although less than 20% of the seeds sown had produced seedlings. Laboratory tests after 4 to 8 years'dry slorage showed seeds of both species to be viable. The maximum survival of viable seeds, estimated by seedling-emergence, was 61 months for A. fatua and 33 months for A. Indoviciana . Seeds of A. fatua survived slightly longer at 15 cm than in the top 5 cm of soil. Survival of A. ludoviciana was less affected by depth and cultivation, except that birds ate some shallow-sown spikelets in the first fortnight after sowing. A. fatua germinated in spring and autumn, and A. tudoviciana in winter, irrespective of age of seed and cultivation of soil. Frozen soil delayed emergence of A. ludoviciana seedlings lor varying periods between December and March. Seedlings of A. ludoviciana were slightly more winter-hardy than A. fatua . More seedlings of A. fatua appeared in the second spring than at any other time, but 80% of the seedlings of A. ludoviciana appeared in the first autumn and winter.
Effets de la profondeur d'enfouissement des graines et de la fréquence des façons culturalles sur la longévité et la germination des semences de Folle-Avoine (Avena fatua L. et A. ludoviciana Dur .)     

New weed species recently introduced into Morocco

Twelve species were identified as having been introduced into Morocco since 1980. These were Abutilon theophrasti Medik., Ammannia coccinea Griseb. Brachiaria eruciformis (Smith) Griseb. Corchorus olitorius L. Cyperus difformis L., Dactyloctenium aegyptium (L.) Richt., Echinochloa phyllopogon (Stapf) Koss, Euphorbia heterophylla L., Kochia scoparia (L.) Schrad., Panictun capillare L., Solanum cornutum Lam, and S. elaeagnifolium Cav. They were possibly introduced with contaminated crop seeds. With the exception of S. cornutum , which has disappeared from the site where it was first collected in 1987, the other species are becoming major weeds in one or more provinces. Details of their biology and importance are discussed.     

不同环境因素对猪殃殃种子萌发及出苗的影响

为探讨猪殃殃种子萌发的适宜环境条件,通过室内萌发试验研究了温度、光照、pH、水势、盐分对猪殃殃种子萌发以及埋土深度对其出苗的影响。结果表明,猪殃殃种子萌发的适宜环境条件为温度10~20℃、光暗12h交替培养以及pH 4~10,萌发率可达到50%以上。猪殃殃种子对水势比较敏感,萌发率随着水势的降低而降低,当水势为0时,萌发率为50.50%,水势降低至-0.6 MPa时,仅有个别种子萌发,萌发率为3.50%,当水势为-0.7 MPa时,种子萌发完全受到抑制;猪殃殃种子对盐分胁迫有一定忍耐力,当NaCl浓度为0.16mol/L时,仍有少数种子萌发,萌发率为16.50%;适于猪殃殃种子出苗的埋土深度是1~2cm,出苗率达到49.50%。研究结果为猪殃殃的出苗调控和综合治理提供了依据。     

南京市小麦田杂草调查及其防除对策

通过对南京市各县区麦田杂草的系统调查,探讨本地小麦田杂草群落结构及发生规律,调查发现目前南京市小麦田间常见杂草有11科26种,主要杂草有猪殃殃、播娘蒿、看麦娘、荠菜、大巢菜、牛繁缕、婆婆纳、麦家公、野燕麦、泽漆等。并对已有小麦田杂草农业防除配套技术进行了充实和完善。     

扬州市麦田草相特点及杂草防除对策

为了摸清扬州地区麦田杂草种类、分布状况,通过倒“W”形九点取样法调查,结果表明麦田杂草有26科81种,其中里下河地区优势种为日本看麦娘、牛繁缕、菵草等;沿江地区优势种为菵草、日本看麦娘、牛繁缕等;丘陵山区优势种为日本看麦娘、猪秧秧、野老鹳等;同时发现当前存在着杂草抗药性增强、防治技术不到位等方面问题,提出了强抓土壤封闭处理、合理选用除草剂及开展技术宣传培训等对策。     

THE DISTRIBUTION OF AVENA FATUA L., AVENA STRIGOSA SCHREB. AND AGROPYRON REPENS (L.) BEAUV. IN BARLEY CROPS IN THE WEST OF SCOTLAND

Summary. A survey of barley crops on 166 west of Scotland farms in 1969 indicated a more widespread distribution of Avena fatua L. than had previously been recognized. Whilst only 0·8% of the barley area was infested with A. fatua , the weed was found on 16% of the known barley-growing farms. A. fatua was associated with arable farming situations and with fields where there was a recent history of cereal cropping. Only on four of the sample farms where A. fatua was found had any attempt been made to control the weed. It is concluded that there is a strong case for eradicating or at least containing the weed before it becomes a major problem.
The distribution of Avena strigosa Schreb. and Agropyron repens (L.) Beauv. is also given.
Distribution d' Avena fatua L., d' Avena. strigosa Schreb. et d' Agropyron repens (L.) Beauv. dans les cultures d'orge de l'ouest de l'Ecosse     

贵州省烟田杂草优势种调查

采用野外调查、室内鉴定与数据统计相结合的方法,对贵州省烟田杂草优势种进行了调查.结果表明,贵州省烟田杂草共有173种,隶属40科124属.其中优势种杂草10种,分别是牛膝菊、马唐、早熟禾、繁缕、牛繁缕、鸭跖草、猪殃殃、苦荞麦、尼泊尔蓼、垂盆草.     

Influence of climatic conditions and plant physiology on glufosinate-ammonium efficacy

Under field conditions the efficacy of glufosinate-ammonium on Galium aparine L. is quite often variable. Experiments under controlled conditions with G. aparine and the more susceptible species Brassica rapa L. showed that especially low relative humidity (r.h.) and low light intensity reduced the accumulation of ammonia in the plants and glufosinate-ammonium performance. As the light intensity under field conditions always exceeds the intensities applied in the experiments this parameter may not be of practical importance. In contrast, low r.h. often occurs under field conditions and could explain the variable G. aparine control. A retention study showed that retention on G. aparine was significantly higher than on B. rapa but ammonia accumulation in the plants indicated that glufosinate-ammonium uptake by G. aparine was lower than that by B. rapa . Glufosinate-ammonium performance was improved on both species by adding ammonium sulphate to the spray solution; however, the increase in efficacy by ammonium sulphate was two times higher for G. aparine than for B. rapa . Ammonia accumulation in untreated plant parts after glufosinate-ammonium application indicated some translocation of glufosinate-ammonium in B. rapa but none in G. aparine .     

Influence of nitrogen on competition between cereals and their natural weed populations

The effects of nitrogen fertilizer on the growth and density of natural weed populations in spring barley (Hordeum vulgare L.) and winter wheat (Triticum aestivum L.) were investigated in the absence of herbicide. An increased level of applied nitrogen did not enhance: weed germination, tended to decrease the total weed biomass and had a differential effect upon the biomass of individual weed species in both wheat and barky. In competition with barley, Chenopodium album L. and Lamium spp. had lower nitrogen optima than the crop, while Urtica urens L. had a higher nitrogen optimum. In competition with wheat, Stellaria media (L.) Vill., Lamium spp. and Veronica spp. had lower nitrogen optima than the crop. The systematic changes in nitrogen effect with time were analysed by fitting orthogonal polynomials to the growth and density curves. The methodology could be recommended for other studies in which time or other systematic factors are included, as it supplies information which a traditional analysis of variance cannot provide. Since seed production is positively correlated with biomass, so nitrogen level affects seed production and, hence, the seed pool and future weed population, suggesting that fertilizer usage can be exploited in an integrated programme of crop: weed management. A trend towards lower N fertilizer application owing to concerns about the environment willfavour most of the weed species investigated in these experiments and change the composition of weed populations.     

Potentiel semencier des terres arables

L'estimation du Potentiel sernencier a été faite sur 50 Parcelles de grande culture de Cô-d'Or. Dans des sols de texture argileuse à sableuse. Le Potentiel semencier mesuré sur 30 cm de hauteur, varic de 400 à 86 500 semences par mètre carré, avec une moyenne de 11 600 et une médiane de 5100 semences par métre carré. Par station on a dénombré en moyenenne 21 espéces, les espèces les plus fréquentes sont Alopecurus myosuroïdes, Anagallis arvensis, Capsella bursa pastoris, Chenopodium album et Kickxia spuria. La viabilité moyenne des semences extraites du sol est estimée à 82,7% avec des fortes variations selon les epèces, de 31% chez Veronica hederifolia à 99% chez Chaennorhinum minuss ou Sonchus asper, mais il n'a pas été possible de vérifier si les graines qui n'ont pas germé sont profondément dor-mantes ou mortes. Le potentiel semencier du sol est un meilleur estimateur de la présence des mauvaises herbes dans les parcelles cultivées que les levées au champ, sauf pour des espéces à grosses graines, comme Avena fatua ou Galium aparine. Weed seed banks of arable fields The weed seed content of arable fields was determined for 50 clayey to sandy soils of the Côte-d'Or. The weed seed bank in the 0–30 cm soil layer varied from 400 to 86 500 seed m^-2 with an average of 11 600 and a median of 5100 seeds m^-2. The mean number of species by field was 21 and the most frequent species were Alopecurus myosuroides, Anagallis arvensis. Capsella bursa pastoris, Chenopodiun album and Kickxia slpuria. The mean viability of the buried seeds was 82·7%, with a large range between species, from 39% for Veronica hederifolia to 99% for Chaenorrhinum minus of Sonchus asper. It was not possible to determine if the ungerminated seeds were deeply dormant or dead. The seed bank is a better indicator of the frequency of weeds in arable fields than the actual flora, except for large seeded species such as Avena fatua of Galium aparine. Der Unklrautsamenvorral in Ackerböden In 50 tonigen bis sandigen Böden der Côte-d'Or wurde der Gehalt an Unkrautsamen bestimmt, Der Samenavorrat in der Bodenschicht van 0–30 cm Tiefe variierte zwischen 400 und 86 500 Samen m^-2, bei einem Durchsehnitt von 11 600 und einem Medianwert von 5100 Samen m^-2. Im Mittel waren pro Feld 21 Arten vertreten; am häufigsten wurden gefunden: Alopecurus myosuroides, Anagallis arvinsis, Capsella bursa pastoris, Chenopodium album und Kickxia spuria. Durchschnittlich waren 82,7% der Samen lebensfähig, wobei grosse Differenzen zwischen de Arten festgestellt wurden. Veronica hederifolia wies cine Keimfähigkeit von 36% auf. Während diese bei Chaemorrhinum minus oder Sonchus asper bei 99% lag. Es war nicht möglich festzustellen job die ungekeimten Samen tot oder völlig dormant waren. Der Samenvorrat im Boden ist ein besscrer Indikator für die Häfigkeit von Unkräutern als die bestehende Flora; eine Ausnahme bilden grossamige Arten wie Avena fatua oder Gulium aparine.     

Entwicklung, Samenbildung und Biomasseproduktion ausgewählter Problemunkrautarten in Rapshalbzwerghybriden

Recently semi-dwarf oilseed rape varieties appeared in practical cropping. So far, only few studies about their properties in combination with weeds are available. Recently however an increasing number of weeds that are difficult to control are observed in oilseed rape. For the experiment Anchusa arvensis (L.) M.??Bieb., Sisymbrium officinale (L.) Scop. and a mixture of three different Geranium species were selected to study their development, seed and biomass production. Consequences for cropping on semi-dwarf oilseed rape cultivars were derived from the results. Three rape cultivars different in plant height were chosen for the experiments: the normal growing variety “Viking”, the semi-dwarf variety “PR45D01” and a full dwarf rape biotype for breeding purposes. In contrast oilseed rape with normal height, infestation of light-indigently and high growing weeds is more probable in semi-dwarf oilseed rape varieties. These weeds show increased biomass production and higher seed production per plant.     

Seasonal emergence of weeds in cultivated soil in New Zealand

Patterns of seedling emergence of ten weed species from soil cultivated at intervals of approximately one month are described. All species examined showed clearly defined emergence patterns. Polygonum persicaria L. seedlings emerged in spring and early summer. Seedlings of Chenopodium album agg., Portulaca oleracea L. and Solanum nigrum L. emerged in late spring, summer and early autumn.Plantago major L., Rumex spp. (mostly R. obtusifolius L.) and Trifolium spp. (mostly T. repens L.) emerged mostly in spring and early summer. Coronopus didymus (L.) Sm. and Juncus bufonius L. tended to emerge in both autumn and spring.Veronica persica Poir. emerged in spring, summer and autumn. Close similarity between emergence patterns in New Zealand and northern Europe, despite differences in rainfall and temperature, suggests that annual dormancy:nondormancy cycles of seeds buried in the soil are largely responsible for seedling emergence patterns. In New Zealand, seedling emergence tended to be more spread out than in Europe, although seasonal patterns were still distinct. Further work on dormancy cycles in these species would be useful, as would a comparison of the factors inducing and breaking dormancy of comparable seed populations in northern and southern Europe and New Zealand. When seeds were left buried for several years before being encouraged to germinate, seedling emergence patterns tended to be of smaller amplitude, although the overall patterns were still very similar.     

Notes on mites of the family Myobiidae (Acari: Prostigmata) parasitising rodents (Mammalia: Rodentia) in Iran

Six mite species of the family Myobiidae, Radfordia (Austromyobia)persica sp. n., Radfordia (Austromyobia) merioni Bochkov, Dubinina et Chirov, 1990, Radfordia (Radfordia) acomys Fain et Lukoschus, 1977, Radfordia (Radfordia) affinis (Poppe, 1896), Radfordia (Graphiurobia) dyromys Fain et Lukoschus, 1973, and Myobia (Myobia) murismusculi (Schrank, 1781) were found in Iran on the rodents Gerbillus cheesmani Thomas, Meriones libycus Lichtenstein, Acomys cahirinus (Desmarest), Alus musculus L., Dryomys nitedula (Pallas), and Mus muscullus, respectively. R. (A.) persica is described as a new species from the female, male and tritonymph. The other five myobiid species are new to Iran.