入侵植物刺苍耳对小麦和苜蓿种子的化感作用

采用生物实验法,研究刺苍耳（[WTBX]Xanthium spinosum[WTBZ]）不同构件的水浸提液对小麦和苜蓿种子的化感效应。结果表明:刺苍耳植株不同构件的提取液对小麦和苜蓿种子的萌发均具有较强的抑制作用,而根、茎和叶水浸液产生显著抑制作用的起始浓度分别为0.012 50 g·mL-1,且化感作用随浸提液浓度的增加而增强。刺苍耳根、茎、叶水浸液对小麦和苜蓿种子萌发的抑制, 不仅表现为降低种子的最终发芽率,还表现为延长种子的萌发周期。不同构件水浸液的化感效应强度整体表现为：叶＞根＞茎,并且化感效应强度随水浸液浓度的增加而增强。     

银胶菊对苘麻化感作用初步研究

通过室内培养皿法,研究了银胶菊水浸提液对苘麻种子萌发和幼苗生长的影响.结果表明,根、茎、叶、花水浸提液的化感作用强度存在差异,花、叶水浸提液对苘麻的化感抑制强度高于根、茎,且抑制强度随处理浓度的升高而增强;在20％浓度下,花、叶水浸提液完全抑制苘麻幼苗生长,对苘麻种子萌发的抑制率分别为91.9％、78.4％.     

木薯对伴生杂草化感作用的初步研究

以白菜和木薯园伴生杂草(假臭草、三叶鬼针草)为受体植物,采用生物测定的方法研究了新鲜木薯叶片4种浸提液的化感作用.结果表明,4种浸提液对受体植物种子萌发率、根长和茎长的生长发育均有不同程度的抑制作用,且浓度越大抑制作用越强;其中乙酸乙酯和水浸提液的抑制作用较强,甲醇和氯仿浸提液的抑制作用相对较弱.研究表明,木薯叶浸提液中含有抑制伴生杂草(假臭草和三叶鬼针草)种子萌发和幼苗生长的化感物质,为进一步开展具有化感潜力木薯品种的研究提供了理论基础.     

银胶菊植株水浸提液对几种植物的化感作用

以萝卜、黄瓜、三叶鬼针草和马唐4种植物的种子为供试对象,测定了银胶菊植株水浸提液的化感活性.结果表明:(1)低浓度(0.01 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜种子的萌发没有影响,相对萌发率均为100%,而对萝卜和黄瓜幼苗的生长却表现为促进作用,相对苗长分别为174.3%和103.9%,相对根长分别为151.9%和103.9%;(2)高浓度(0.5 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强;(3)不同浓度的银胶菊植株水浸提液对三叶鬼针草和马唐的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强.其中,当水浸提液浓度为0.5 g/ml时,三叶鬼针草和马唐的种子相对萌发率为0,受到强烈的化感作用.     

三叶鬼针草化感作用的初步研究

运用生物测定法,对三叶鬼针草的化感作用进行研究。比较了用不同部位及其不同浓度水浸提液对不同作物化感作用的差异,并初步探讨了三叶鬼针草对小麦和莴苣幼苗生长的化感机制。结果表明,三叶鬼针草不同部位水浸提液对2种受体植物影响均表现出抑制效应,其强弱为叶>茎>根。其水浸提液对2种受体植物的种子萌发、幼苗生长和光合色素均有显著的抑制作用。Peason相关性分析表明,叶绿素A和叶绿素b含量与水浸提液浓度存在显著的负相关性,类胡萝卜素无明显变化。丙二醛随浓度增加而有上升趋势,但差异不显著,说明三叶鬼针草对受体植物膜的透性影响不大。     

大叶芥菜对牛膝菊的化感作用潜力

以牛膝菊为受体,研究大叶芥菜水浸提液对牛膝菊的化感作用。结果显示,浓度分别为0.250 00、0.125 00、0.062 50、0.031 25 g/m L的大叶芥菜水浸提液对牛膝菊种子的萌发抑制效应以0.250 00 g/m L最高,平均抑制率为56.03%;低浓度(0.031 25 g/m L)处理对牛膝菊种子萌发基本上没有抑制作用。此外研究发现,大叶芥菜水浸提液对牛膝菊胚根、胚芽的萌发和鲜质量积累都有明显的抑制作用,对鲜质量平均抑制率分别为75.75%、35.82%、17.48%、18.81%;对牛膝菊种子萌发、胚根、胚芽、鲜质量的化感综合效应分别为60.36%、30.45%、14.23%、16.50%。结果表明,大叶芥菜对牛膝菊有很强的化感潜力,能为牛膝菊的绿色防控提供理论依据。     

茼蒿水浸液和挥发物对三七根腐病菌的抑制活性及其抑菌物质分析

为明确茼蒿水浸液和挥发物对三七根腐病菌的抑制活性及主要的抑菌物质,采用菌丝生长速率法测定其对腐皮镰刀菌Fusarium solani F-3和锈腐病菌Ilyonectria destructans RS006的抑制活性,利用气相色谱-质谱联用仪分析水浸液和挥发物的成分,进一步验证化合物的抑菌活性。结果表明,茼蒿茎、叶水浸液对F-3的抑制效果强于RS006,叶水浸液比茎水浸液抑菌效果更好。叶水浸液浓度为15.0%时,对F-3的抑制率为55.1%。挥发物对RS006的抑制活性存在明显的浓度效应,茎叶用量为2.0 g/皿时,茎和叶挥发物对RS006的抑制率均高于85.0%。茼蒿茎挥发物对F-3的抑制率较低且不同浓度间差异不显著,叶挥发物在叶用量为1.0 g/皿时对F-3抑制效果最好,抑制率为35.3%。茼蒿茎水浸液的主要成分为糖类和有机酸类,叶水浸液的主要成分为有机酸类。茼蒿茎叶挥发物的主要成分为萜烯类。挥发物中芳樟醇对两种病原菌的抑制效果较好。利用茼蒿或其化感物质可为三七根腐病的绿色防控提供思路。     

野老鹳草水提取物对大豆、玉米、花生的化感作用

采用室内生物测定法研究野老鹳草(Geranium carolinianumL.)不同浓度(0、0.100 00、0.050 00、0.025 00、0.012 50、0.006 25 g/mL)茎水浸液对3种植物的化感作用。结果表明,野老鹳草水浸提液对3种受体植物种子萌发和幼苗生长均存在化感作用,且化感作用大小与水浸液浓度呈正相关;所有浓度的野老鹳草茎水浸提液对大豆、玉米的化感综合效应均为负值;0.10、0.05 g/mL野老鹳草茎水浸提液对花生的化感综合效应为负值,即表现为抑制作用;0.025 00、0.012 50、0.006 25 g/mL野老鹳草茎水浸提液对花生的化感综合效应为正值,即表现为促进作用;3种受体植物对野老鹳草的化感作用敏感程度不同,玉米对野老鹳草茎水浸液较敏感,而花生、大豆对野老鹳草茎水浸液较不敏感。     

小花棘豆根、茎、叶水浸液对3种草原植物的化感作用

小花棘豆(Oxytropis glabra)是多年生有毒草本植物,在退化的草场上可成为优势杂草,扁蓿豆(Melilotoides ruthenica)、草木樨状黄芪(Astragalus melilotoides)、沙芦草(Agropyron mongolicum)为草原常见优质牧草。以小花棘豆为供体植物,分别研究其不同浓度的根、茎叶水浸液对上述3种受体植物种子发芽的影响。结果表明:根、茎叶水浸液对受体植物发芽率、发芽指数、胚根与胚芽长均有不同程度的化感作用,两种水浸液对3种植物发芽指数的化感效应均强于发芽率,对胚根长的化感效应均强于胚芽长。供体植物的不同部位对不同受体植物的化感效应有明显的差异,茎叶水浸液的化感效应强于根水浸液,综合效应结果显示:3种受体植物对两种水浸液化感作用的敏感性依次为:沙芦草草木樨状黄芪扁蓿豆。不同质量浓度根、茎叶水浸液对受体植物的影响表明,浓度越大化感效应越强,高质量浓度(≥10 mg·m L~(-1))水浸液抑制作用显著,低质量浓度水浸液(≤5 mg·m L~(-1))化感作用不显著。     

圆柏果实水浸提液化感作用的初步研究

圆柏(Sabina chinensis L.)成年母树周围很少有实生苗生长,为了检测该植物组织是否具有抑制种子发芽的作用,通过测定圆柏果皮和种子水浸提液对萝卜、白菜和圆柏种子萌发及幼苗根长和苗高的影响,对圆柏果实化感物质的作用进行了研究。结果显示:在高浓度0.1 g/mL果皮水浸提液处理下,萝卜和白菜种子的萌发、苗高和根长生长均受到显著的抑制作用,随着浸提液浓度的降低,其抑制作用逐渐减弱;低浓度(0.01 g/mL,0.03 g/mL)的果皮水浸提液对萝卜种子的萌发、幼苗苗高和根长均表现为促进作用,对白菜种子萌发、幼苗苗高和根长有抑制作用;圆柏种子浸提液对萝卜、白菜种子萌发及幼苗生长的抑制作用不显著。圆柏果实水浸提液对萝卜和白菜具有明显的化感作用,化感物质主要存在于果皮中,而且圆柏果实的化感作用对参加试验的萝卜和白菜种子具有选择性。圆柏种子在该试验中未发芽,TTC法检测参加试验圆柏种子的活力,发现果皮浸提液处理的圆柏种子有34%具有生活力,子叶在转绿;种子浸提液处理的圆柏种子有37%具有生活力,子叶也在转绿,圆柏种子的发芽率比较低,很大程度上取决于种子的质量,圆柏对自身种子的发芽及幼苗生长的自毒效应需要进一步研究。     

The effect of bacterial fermentation of couch grass rhizomes and Fusarium culmorum on the growth of barley seedlings

Phytotoxic concentrations of acetic acid were found in extracts of decaying rhizomes of couch grass ( Agropyron repens ) kept in sand at different moisture levels. Leaf extension of barley seedlings was inhibited by inoculating the radicles before planting with Fusarium culmorum and this inhibition was increased by 5 mM acetic acid. Seed dressings of benomyl and thiram alleviated the inhibition of leaf growth of seedlings grown in sand containing rhizomes inoculated with F. culmorum .     

地肤地上部水浸提液对胡麻的化感机理研究

为了探明地肤地上部水浸提液对胡麻的化感机理,以盆栽试验结合实验室分析,研究了不同浓度的地肤地上部水浸提液对胡麻抗氧化性酶——超氧化物歧化酶(SOD)、过氧化物酶(POD)活性及脂质过氧化产物——丙二醛(MDA)含量的影响。结果表明,在不同浓度地肤地上部水浸提液胁迫下,胡麻的SOD、POD活性均随着胁迫时间的延长呈先升高后降低的趋势,MDA含量呈平稳上升趋势;在同一处理时间段,随着处理浓度的升高,SOD、POD活性促进(抑制)率变大,MDA含量增大。表明地肤地上部水浸提液化感物质对胡麻保护性酶活性和膜脂过氧化作用有重要影响。     

Inhibitory effects of aqueous extracts of black mustard on germination and growth of alfalfa

The present study investigated the allelopathic effects of various black mustard ( Brassica nigra L.) plant parts on alfalfa germination and seedling growth. Aqueous extracts of black mustard ( Brassica nigra L.) leaf, stem, flower and root plant parts were made to determine their effects on germination and dry weights of hypocotyl, and radicle length of 5-day-old alfalfa seedlings over a range of extract concentrations. All aqueous extracts significantly inhibited alfalfa seed germination and seedling growth when compared with the distilled water control. Increasing the aqueous extract concentrations of separated Brassica nigra plant parts significantly inhibited alfalfa germination, seedling length and weight. Based on significant radicle length reactions to aqueous extracts, the toxicity may be classified in the following order of decreasing inhibition: flower, leaf, mixture of all plant parts, root, and stem. Increasing the concentration of aqueous flower extracts significantly inhibited the water uptake by germinated alfalfa seeds. The greatest inhibition in water uptake occurred at a 12 g kg⁻¹ extract concentration for seeds soaked for 8 h.     

Velvetbean (Mucuna pruriens) extracts: impact on Meloidogyne incognita survival and on Lycopersicon esculentum and Lactuca sativa germination and growth

Velvetbean (Mucuna spp.) is a summer annual that has been used as a cover crop to reduce erosion, fix nitrogen and suppress weeds and plant-parasitic nematodes. Crude aqueous extracts (1:15 dry weight plant/volume water) were made from velvetbean plant parts, and various concentrations of the extracts were evaluated in vitro for toxicities to different stages of Meloidogyne incognita (Kofoid and White) Chitwood and for suppression of hypocotyl and root growth and inhibition of germination of tomato (Lycopersicon esculentum L.) and lettuce (Lactuca sativa L.). Germination was only affected by the full-strength extract from leaf blades. Lettuce root growth was the most sensitive indicator of allelopathic activity of the plant part extracts. Lettuce and tomato root growth was more sensitive to the extract from main roots than to extracts of other plant parts, with lethal concentration (LC50) values of 1.2 and 1.1% respectively. Meloidogyne incognita egg hatch was less sensitive to extracts from velvetbean than the juvenile (J2) stage. There was no difference among LC50 values of the extracts from different plant parts against the egg stage. Based on LC50 values, the extract from fine roots was the least toxic to J2 (LC50 39.9%), and the extract from vines the most toxic (LC50 7.8%). The effects of the extracts were nematicidal because LC50 values did not change when the extracts were removed and replaced with water.     

Potential allelopathic effects of Mikania micrantha on the seed germination and seedling growth of Coix lacryma‐jobi

The allelopathic potential of Mikania micrantha H.B.K. to affect the seed germination and seedling growth of Coix lacryma‐jobi L. was investigated. Water‐soluble allelopathic substances were found in the water extracts of M. micrantha. The effect of the water extracts on the seed germination and seedling growth of C. lacryma‐jobi was concentration‐dependent. The water extracts from the different plant parts (leaf, stem, and root) of M. micrantha differed in their effect on the germination and seedling growth of C. lacryma‐jobi, with the effect of the leaf extract being the least inhibitory. The malondialdehyde (MDA) content in the C. lacryma‐jobi seedlings increased by 64%, 45%, and 52% of the control with increasing concentrations of the extracts of the root, stem, and leaf (80, 400, and 400 g L^?1, respectively). The extract from the M. micrantha roots significantly increased the catalase (CAT) activity of the C. lacryma‐jobi seedlings (48% and 54% of the control at the concentrations of 20 g L^?1 and 80 g L^?1, respectively). The extracts from the leaves and stems at low concentrations increased the CAT activity, but at high concentrations, the extracts decreased the CAT activity. The extracts from the roots, stems, and leaves at concentrations of 80, 400, and 400 g L^?1 also significantly decreased the peroxidase (POD) activity of the C. lacryma‐jobi seedlings to 27%, 52%, and 34% of the control, respectively. These results indicate that the water extracts of M. micrantha could inhibit the seed germination and seedling growth of C. lacryma‐jobi through the regulation of anti‐oxidase activity, such as POD and CAT in the cells. The growth inhibition of the C. lacryma‐jobi seedlings is probably related to injury after oxidization of the cell membranes with the increase of MDA content.     

苍耳等14种植物对植物病原菌的抑菌活性

以番茄灰霉菌、辣椒丝核菌、黄瓜枯萎菌、黄瓜黑星菌和番茄早疫菌为供试菌,用生长速率法和孢子萌发法对14种植物提取物的离体生物活性进行了测定。结果表明:在供试质量浓度为0.1 g/mL时,苍耳茎叶、百部根、龙葵对辣椒丝核菌和黄瓜枯萎菌的抑制率达到100%;黄花蒿、苦参根、狼毒根对5种供试菌的抑制率均在60%以上。苍耳根、苍耳茎叶、泽漆、苦参根、龙葵、黄花蒿、蒲公英提取物至少对1种供试菌孢子萌发抑制率大于90%。本试验中,苍耳茎叶和根提取物对供试菌的菌丝生长和孢子萌发均显示了很高的抑制作用。     

油茶害虫植物源引诱剂筛选及其诱集的昆虫种群动态

通过16种植物提取物对油茶林昆虫进行诱捕,筛选出2种对油茶害虫引诱效果较好的植物提取物,并在油茶林进行引诱效果及诱集昆虫种群动态的研究。结果表明,2016年4月-8月的引诱试验中,共诱集到昆虫7 455头。其中油茶叶片水提粗提物诱集到昆虫数量最多,达4 368头,诱虫谱较广,诱集到23种昆虫,可以诱集为害油茶林的害虫主要有假眼小绿叶蝉、琼凹大叶蝉、大青叶蝉、白痣广翅蜡蝉、茶角胸叶甲等;其次为油茶乙醇粗提物,诱集到2 078头昆虫,且对八点广翅蜡蝉、小蠹类害虫的诱捕效果最佳。植物提取物作为引诱剂,可为油茶林害虫的发生期、发生量的监测预报提供直接的、客观的依据。     

Effects of neem (Azadirachta indica) seed kernel extracts from different solvents on the carmine spider mite,Tetranychus cinnabarinus

Extracts of neem (Azadirachta indica A. Juss) seed kernels prepared from various solvents affected the behavior and fecundity of the carmine spider mite,Tetranychus cinnabarinus (Boisd.). Bean leaf discs freshly sprayed with different concentrations of the extracts strongly repelled the females from the treated leaves and egg-laying was reduced. On the basis of EC 50s for both parameters, the order of effectiveness of the extracts was pentane > chloroform >n-butanol > acetone > methanol > H₂ 0 (inactive). The activity decreased with increasing dielectric constant of the extracting solvent. The chloroform and butanol extracts in the original solvents were phytotoxic. Bean leaf discs 7 days after spraying with the pentane and acetone extracts, still caused mortality and reduction in fecundity of adult females, but no repellency. The acetone and the pentane extracts sprayed directly on adult female mites on bean leaf discs, caused repellency and reduction of fecundity and also mortality of adults.     

蛇床子提取物对茄子根际土壤中黄萎菌数量及植株抗病性的影响

本试验以茄子根际土壤黄萎菌为作用对象,采用浓度为2、4、8、10 mg/mL的蛇床子提取物,通过田间灌施,配合伤根接菌的方法处理茄子幼苗,探讨蛇床子提取物对根际土壤黄萎菌抑制作用及其对植株抗病性的影响.结果表明,不同浓度蛇床子提取物均可抑制茄子黄萎病的发生,其中浓度为8 mg/mL效果最为显著.与清水对照相比,根际土壤中的黄萎菌数量减少了56.67％～69.23％;茄子植株的发病率和病情指数分别减少了53.12％～54.98％、51.26％～56.82％;生长指标的增幅分别为:株高3.68％～9.59％、茎粗3.41％～9.98％、地上部鲜重4.43％～9.47％、根鲜重2.61％～9.57％、叶面积3.56％～9.55％;防御酶活性也有所增加,增幅分别为:过氧化物酶(POD)45.60％～64.23％、多酚氧化酶(PPO)108.62％～255.00％、苯丙氨酸解氨酶(PAL)62.32％～76.04％.上述结果表明,蛇床子提取物会抑制茄子黄萎病的发生,增加植株的抗病性,促进植株生长.