Biocontrol options for Cirsium arvense with indigenous fungal pathogens

As a first step in the development of a mycoherbicide for biological control of Cirsium arvense indigenous fungal pathogens that had been isolated from diseased hosts were tested both singly and in combination on potted plants under environmental conditions. Disease symptoms (necroses, chloroses and macerations) and parameters of growth and development were evaluated to determine the potential for weed control. During 1998, Phoma destructiva, Phoma hedericola, a Mycelia sterilia and Puccinia punctiformis were inoculated singly. With the exception of the obligate biotroph P. punctiformis (local infections), the single inoculations reduced the measured parameters. A combined inoculum of P. punctiformis and Ph. hedericola was less effective than Ph. hedericola alone. In 1999, Ph. hedericola, Ph. destructiva, Ph. nebulosa and the Mycelia sterila were applied both singly and as a combined inoculum. Of all the tested inocula, the mixture of four pathogens had the greatest potential for biocontrol, significantly reducing reproductive capacity of the plants. These results demonstrate the importance of taking advantage of synergisms in developing a mycoherbicide.     

加拿大蓟天敌─欧洲方喙象的寄主专一性测定

在温度为25～28 ℃的养虫室内选择具有代表性的菊科植物及豆科、禾本科牧草共10科30种植物对欧洲方喙象进行寄主专一性测定试验，结果表明其食性专一，只取食加拿大蓟，个别成虫或幼虫在饥饿状态下仅少量取食菊科其他植物，但随后即拒绝取食。非选择性试验（饥饿试验）表明欧洲方喙象耐饥饿能力强，不同龄期平均达28 d。欧洲方喙象最适宜的生长温度是25 ℃，高于30 ℃或低于10 ℃，生长发育则受到抑制。     

Competition between Canada Thistle [Cirsium arvense (L.) Scop.] and Faba Bean (Vicia faba L.)

This study was conducted to investigate whether density, above-ground biomass and nitrogen (N) concentration of Cirsium arvense (L.) Scop. cause serious reductions in faba bean ( Vicia faba L.) yield. A 2-year field experiment (1991–93) with four Cirsium densities (0, 4, 16, 64 plants m^–2) was carried out. Statistical analysis showed a significant effect of Cirsium density on faba bean yield. Multiple regression analysis showed that the main factors causing faba bean yield losses were the density and above-ground biomass of Cirsium . The results of this study demonstrate that Cirsium competition reduces faba bean yield. The mean faba bean yield losses over the 2 years were 10, 12 and 8% for above-ground biomass, seed and stem, respectively, for a Cirsium density of 16 plants m^–2.     

罗汉菜的发展现状与研究进展

主要对罗汉菜这种珍稀的野生蔬菜资源的发展历史、近年的应用现状、植物学特性及栽培技术进行了综述,同时论述了罗汉菜在食品加工、药用等方面的功用,并就其未来的发展趋势提出展望。     

纳米氧化锌消毒小蓟外植体应用研究

为使纳米氧化锌在组织培养中达到最佳消毒效果,以小蓟叶片外植体为材料,建立纳米氧化锌消毒的组织培养无菌体系。结果表明:纳米氧化锌浓度为1~7g·L~(-1)时,对小蓟外植体消毒效果逐渐提升,褐化率也逐渐升高,不同浓度纳米氧化锌对愈伤组织的诱导和生长没有明显的影响。纳米氧化锌最佳消毒处理浓度为5g·L~(-1),处理外植体20min。2g·L~(-1)纳米氧化锌+0.1%升汞消毒,外植体大约20%有污染,愈伤组织生长良好。3g·L~(-1)纳米氧化锌+0.1%升汞达到最佳的消毒效果,但愈伤组织诱导被抑制,生长缓慢。     

Effect of tillage intensity on weed infestation in organic farming

Conservation tillage is not yet widely accepted by organic farmers because inversion tillage is considered to be necessary for weed control. Three long-term experiments were established with combinations of reduced and conventional plough tillage and stubble tillage to determine weed infestation levels in organic farming, i.e. herbicide application being excluded. Experiment 1 (with very low stocking density of perennial weeds) showed that in presence of primary tillage by mouldboard ploughing the number of annual weeds was nearly unaffected by the mode of stubble tillage. In experiment 2, however, with Canada thistle (Cirsium arvense) being artificially established, thistle density was significantly affected by stubble tillage and by a perennial grass–clover forage crop. Experiment 3 combined two levels of stubble tillage (skimmer plough, no stubble tillage = control) with four implements of primary tillage in the order of decreasing operation depth (deep mouldboard plough, double-layer plough, shallow mouldboard plough or chisel plough). Primary tillage by chisel plough resulted in significantly highest annual weed density compared to all other treatments. The natural C. arvense infestation in experiment 3 showed highest shoot density in the “skimmer plough/chisel plough” treatment compared to the lowest infestation in the “skimmer plough/double-layer plough” treatment. The poor capacity of the chisel plough for weed control was also reflected by the soil seed bank (5500 m⁻² C. arvense seeds for chisel plough, <300 seeds for all other primary tillage). A reduced operation depth of the mouldboard plough (“shallow mouldboard plough”) seemed to have an insufficient effect in controlling C. arvense infestation as well. Stubble tillage by the skimmer plough in addition to nearly any primary tillage operation largely reduced both annual weeds and thistle shoots. Most effective in controlling C. arvense was also a biennial grass–clover mixture as part of the crop rotation.Double-layer ploughing is a compromise between soil inversion and soil loosening/cutting and can be regarded as a step towards conservation tillage. In terms of controlling annual weeds and C. arvense, the double-layer plough was not inferior to a deep mouldboard plough and seems to be suitable for weed control in organic farming. Tilling the stubble shallowly after harvest can support weed control in organic farming remarkably, particularly in reducing C. arvense. If no noxious, perennial weeds occur and primary tillage is done by soil inversion, an omission of stubble tillage can be taken into consideration.     

Floral attractants for the female soybean looper, Thysanoplusia orichalcea (Lepidoptera: Noctuidae)

BACKGROUND: The soybean looper, Thysanoplusia orichalcea (F.), is a polyphagous insect pest of vegetable crops. Indonesian in origin, it has spread to Europe, India, Africa, Australia and New Zealand. The identification of an attractant for female T. orichalcea could enable the development of alternative pest management strategies to those provided by insecticides or sex pheromones, which are often only attractive to males. RESULTS: Traps baited with synthetic lures derived from Canada thistle, Cirsium arvense (L.) Scop., floral volatiles attracted female T. orichalcea. Phenylacetaldehyde, a floral compound attractive to many Lepidoptera and present in C. arvense, was tested alone as an attractant for the soybean looper and caught significantly more female than male T. orichalcea. Trap catch was greatest when phenylacetaldehyde was combined with five prevalent volatiles present in C. arvense headspace collections: 2‐phenylethyl alcohol, methyl salicylate, dimethyl salicylate, benzaldehyde and benzyl alcohol. Twice as many female moths as males were collected. CONCLUSION: Successful trapping of female T. orichalcea in either a lure‐and‐kill or a mass trapping system may offer an effective way to manage its population size. Copyright © 2008 Society of Chemical Industry     

3种盐胁迫对蓟幼苗生长及生理生化的影响

采用盆栽试验研究不同浓度(0.1%、0.2%、0.3%、0.4%、0.5%、0.6%)的NaCl、Na_2SO_4、Na_2CO_3对蓟(Cirsium japonicum)幼苗苗高、叶片相对含水量、丙二醛(MDA)、抗氧化酶(POD、SOD、CAT)以及渗透调节物质(可溶性糖、游离脯氨酸)的影响。结果表明,除0.1%NaCl处理蓟苗高和叶片相对含水量高于无盐胁迫(CK)外,其余处理均低于CK,且随盐浓度增加而降低,其中,0.3%NaCl、0.4%Na_2SO_4和0.1%Na_2CO_3处理下苗高依次为CK的62.15%、58.00%和45.77%,而0.5%Na_2CO_3处理幼苗死亡;随盐处理浓度增加和处理时间延长,叶片中丙二醛含量均呈上升趋势;POD、SOD、CAT活性随盐浓度、时间变化的趋势不尽一致,3种酶活性均出现了阈值,POD出现在0.3%NaCl、0.3%Na_2SO_4、0.4%Na_2CO_3胁迫5d,SOD出现在0.3%NaCl处理3d、0.5%Na_2SO_4处理1d、0.4%Na_2CO_3处理3d,CAT出现在0.3%NaCl、0.2%Na_2SO_4、0.1%Na_2CO_3胁迫3d;相同处理时间下,随盐浓度的增加,除NaCl胁迫下游离脯氨酸(Pro)含量先增后减外,Na_2SO_4和Na_2CO_3胁迫下游离脯氨酸含量,以及3种盐胁迫下可溶性糖(SS)含量均逐渐增加。综上认为,蓟对NaCl、Na_2SO_4、Na2CO4这3种盐均具有一定的耐性,可以在低于0.3%NaCl、0.4%Na_2SO_4和0.1%Na_2CO_3条件下生存和生长。     

问荆(Equisetum arvense L.)根茎水浸液对大豆根际土壤性质、微生物及酶活性的化感效应

[目的]为评价问荆对大豆生长后根际土壤微生态环境的化感效应,[方法]本文研究了不同浓度问荆水浸液处理下大豆根际土壤性质、微生物数量及酶活性的变化。[结果]结果表明,不同浓度问荆水浸液处理下,土壤碱解氮、速效磷、有机质含量随问荆水浸液浓度增加而减少;土壤细菌、真菌、放线菌数量随问荆水浸液浓度增加而减少;土壤过氧化氢酶活性随问荆水浸液浓度增加而升高,脲酶活性随问荆水浸液浓度增加而降低,磷酸酶、转化酶活性未发生变化。[结论]说明问荆产生的化感物质使土壤养分下降,而土壤酶对外来物质有缓冲作用。     

在碱茅和芦苇草地中防除刺儿菜药物筛选试验结果

在碱茅和芦苇人工草地中喷施不同量的甲黄隆、绿黄隆和阔叶净均可有效防除有害杂草刺儿菜（Ｃｉｒｓｉｕｍｓｅｔａｓｕｍ）。刺儿菜的株防效和鲜重防效均与施药量呈正相关。以喷施甲黄隆（２５％）２２．５ｇ／ｈｍ２或绿黄隆（２５％）４．５ｇ／ｈｍ２最好．