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.     

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.     

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。     

肿柄菊水浸提液对3种作物的化感作用研究

采用培养皿滤纸法测定肿柄菊不同浓度水浸提液对豌豆、萝卜和水稻种子萌发、幼苗生长的影响.结果表明:肿柄菊浸提液对豌豆和萝卜种子萌发有抑制和延缓作用,对水稻最终萌发率无显著影响;低浓度的浸提液可促进受体植物幼苗生长,高浓度则有显著的抑制作用,同时还发现高浓度浸提液可降低受体植物叶绿素、可溶性蛋白质和糖的含量.     

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％.     

外来植物黄顶菊根、茎、叶的化感作用初探

对黄顶菊［Flaveria bidentis (L.) Kuntze］营养器官进行了解剖学观察,发现其根、茎、叶均存在分泌结构或分泌物。以白菜（Brassica pekinensis Rupr.）作为受试植物,从白菜种子发芽率、幼苗的简化活力指数、幼苗下胚轴及胚根伸长、幼苗中叶绿素、丙二醛（MDA）及可溶性糖（WSS）含量等指标对黄顶菊根、茎和叶水浸提液的化感作用进行了探讨。研究发现,根、茎、叶的浸提液降低了白菜种子发芽率和幼苗胚根长度;幼苗中叶绿素a及总叶绿素随浸提液浓度的升高最终呈下降趋势;MDA和WSS含量随叶片和茎的浸提液浓度升高相应增加。白菜种子萌发及幼苗生长对黄顶菊不同器官浸提液反应有差异,其对叶片浸提液的浓度响应最明显。     

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。     

假臭草化感作用研究

假臭草(Eupatorium catarium Veldkamp)水浸提液对小白菜和萝卜的发芽率、根生长、茎生长具有不同程度的化感作用,总体上呈现出低促高抑的现象,且随着溶液浓度增大抑制作用也增强。鲜样浸提液浓度为0.25g/m l、0.50g/ml时,小白菜不能发芽、幼苗不能存活。鲜样浸提液浓度为0.50g/ml时,萝卜幼苗不能存活。鲜样浸提液和干样浸提液的化感作用有显著差异。     

播娘蒿、猪殃殃对小麦的化感作用

以10个常规小麦品种为受体,采用室内生物测定法,通过分析麦田杂草播娘蒿、猪殃殃水浸提液对不同小麦品种发芽和幼苗生长的影响,探讨2种杂草对不同小麦品种化感作用的差异,客观评价不同小麦品种的抗草潜力。结果表明,2种杂草对不同品种小麦均存在不同程度的化感作用,以RI值作为化感作用的评价指标,播娘蒿水浸提液对不同品种小麦的化感作用由大到小为衡观35洲元9369山农17周麦24泰山6426西农979新麦26济麦22084380山农21,猪殃殃水浸提液对不同品种小麦的化感作用由大到小为洲元9369周麦24衡观35山农17泰山6426济麦22新麦26084380西农979山农21。     

两种中草药水浸液对小麦条锈病菌的抑制作用研究

采用生物测定方法,研究了中草药苍耳、黄瑞香提取液对小麦条锈病菌的抑制作用。结果表明,小麦条锈病降低小麦种子的生活力,影响小麦幼苗的生长发育。不同浓度苍耳、黄瑞香提取液对小麦条锈病孢子萌发有抑制作用,其中0.50 g/mL苍耳、黄瑞香提取液其抑制率分别为69.29%和64.44%;不同浓度的中草药苍耳、黄瑞香提取液对小麦条锈病菌丝生长均有抑制,0.50 g/mL苍耳、黄瑞香提取液效果最好,抑制率分别为55.44%和44.77%,与对照相比差异都达显著性水平。     

狗尾草水提取物对6种植物的化感作用

采用室内培养皿法测试了狗尾草地上部分水浸提液对小麦、高梁、绿豆、黄瓜、萝卜等农作物和牛筋草（杂草）的化感作用。结果表明：狗尾草水浸提液对植物种子萌发和幼苗生长具有较高的化感抑制作用;当水浸提液的质量浓度为0．0250g／mL时,除绿豆外,小麦、黄瓜、萝卜和高粱等农作物的种子萌发均受到显著或极显著的抑制作用,其发芽率的彤值分别为-0．56、-0．17、-0．28、-0．27;在0．0500g／mL浸提液处理下,除黄瓜苗高、苗鲜重、根鲜重、绿豆根鲜重外,5种农作物根和苗的生长受到极显著的抑制,小麦、绿豆、黄瓜、萝卜、高粱根长的脚值分别为-0．75、-0．60、-0．61、～1．00、-0．61;当浸提液浓度为0．030g／mL时,牛筋草种子不能萌发,而小麦、绿豆的叶绿素含量和可溶性糖含量则从生理生化水平反映出不同程度的化感效应。综合研究结果可知,狗尾草显示出极强的化感作用,为进一步分离、鉴定和开发环境友好型除草剂提供了理论依据和支持。     

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。     

Litter-mediated allelopathic effects of kudzu (Pueraria montana) on Bidens pilosa and Lolium perenne and its persistence in soil

This study investigated the allelopathic effects of kudzu litter on the seed germination and early growth of Bidens pilosa and Lolium perenne . The bioassays, with various concentrations (10, 20, 30, 40, and 50 g L⁻¹) of aqueous kudzu litter leachate, significantly affected the germination percentages and radicle growth of both species. These parameters decreased progressively when the seedlings were exposed to increasing concentrations of leachate. The root and shoot length, dry weight, and chlorophyll concentration of the B. pilosa and L. perenne seedlings also were significantly affected when they were grown in leachate-amended soil. However, the chlorophyll fluorescence values of the seedlings subjected to different concentrations of aqueous kudzu litter leachate indicated that the mere presence of leachate in the soil was not stressful for the plants. The seedlings of both species were under stressful conditions only when they were grown in the soil that was treated with higher concentrations of leachate (30, 40, or 50 g L⁻¹). A 6 week decomposition study of the kudzu litter in soil was conducted to observe the retention of phenolic content in the soil. The results showed that, although the concentration of dissolved organic carbon decreased with increasing decomposition, the phenolic concentration was not significantly affected when the observation period ended. This suggests that the phytotoxic properties of kudzu litter remain stable in soil systems for a considerable amount of time after incorporation into the soil.     

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.     

Plant growth inhibitors in turmeric (Curcuma longa) and their effects on Bidens pilosa

Turmeric (Curcuma spp.) has numerous biological activities, including anticancer, antibacterial, antifungal and insecticidal properties. Here, we evaluated the plant growth‐inhibitory activities of two cultivars of Curcuma longa (C. longa ; Ryudai gold and Okinawa ukon) against radish, cress, lettuce and Bidens pilosa (B. pilosa ). The methanol extracts of both turmeric varieties inhibited the seed germination and seedling growth of all the tested plants. Ryudai gold had a significantly higher inhibitory effect on the seed germination and root and shoot growth of the plants than Okinawa ukon. Therefore, Ryudai gold was chosen for the isolation of plant growth‐inhibitory compounds using a silica gel column and high‐performance liquid chromatography. The structural identification of the compounds was carried out using ¹H NMR, ¹³C NMR and liquid chromatography–tandem mass spectrometry. The growth inhibitors were identified as four curcuminoids; dihydrobisdemethoxycurcumin ( 1 ), bisdemethoxycurcumin ( 2 ), demethoxycurcumin ( 3 ) and curcumin ( 4 ). The IC₅₀ of the curcuminoids against the root and shoot growth of B. pilosa ranged from 8.7 ± 1.7 to 12.9 ± 1.8 and from 15.5 ± 1.8 to 38.9 ± 2.8 μmol L^?1, respectively. Compound 1 showed the lowest IC₅₀ against the root and shoot growth of B. pilosa . These results suggested that Ryudai gold has a potential growth‐inhibitory effect against B. pilosa .     

三裂叶蟛蜞菊对绿豆的化感作用

研究了三裂叶蟛蜞菊各器官水提液对绿豆种子萌发及其幼苗生长的影响。结果表明,各器官水提液浸种能显著降低绿豆种子发芽率,且发芽率随水提液浓度增大而降低;各器官水提液能显著抑制绿豆幼苗的生长,5d后绿豆平均根长随水提液浓度增大而变短;对绿豆种子萌发的化感作用从强到弱依次为茎〉叶〉全株〉根。     

蒙山莴苣化感作用对4种草坪草种子萌发的影响

为了合理地控制草坪生长与管理草坪,初步研究蒙山莴苣[Mulgedium tataricum（L.）DC.]根、叶、茎的浸提液及5个不同浓度茎浸提液对校园内采的高羊茅（Festuca arundinacea Schreb.）、高羊茅千年盛世（Millennium）、一年生黑麦草（Lolium multiflorumL.）蓝天堂（Blue Heaven）、多年生黑麦草（L.perenneL.）球道（Fairway）4种草坪草的化感作用,通过对受体种子发芽率、幼苗长度、根长以及幼苗中过氧化氢酶活性、可溶性蛋白含量等指标的测定发现：蒙山莴苣浸提液对草坪草的种子萌发以及幼苗的生长均表现出抑制作用,其强度为茎〉叶〉根。总体上随着茎浸提液浓度的增大,草坪草受抑制作用有所增强。蒙山莴苣浸提液对幼苗中CAT活性影响各异,且抑制幼苗中可溶性蛋白合成,其中茎浸提液抑制作用最大。     

大葱水提物对辣椒疫病的控制作用及其活性成分分析

为明确大葱水提物对辣椒疫病的控制效果及其主要活性成分,通过室内毒力、田间防效以及GC-MS联用测定发现,大葱茎叶与根水提物均对辣椒疫病菌有一定抑制作用,且浓度越高抑制作用越强。在含300 mg/mL根水提物的平板上培养2 d,辣椒疫病菌菌丝生长的抑制率高达81.50%;但随着时间的推移,抑制作用减弱,5 d后,200 mg/mL根和茎叶水提物对病菌的抑制率仅为34.18%和25.62%。用300 mg/mL大葱水提物灌根,对辣椒疫病的防效可达50%左右。将大葱与辣椒轮作或混栽可有效降低田间辣椒疫病的病情,防病效果分别为40.67%和41.21%。GC-MS测定结果表明,大葱根和茎叶水提物中分别含有14种和28种挥发性物质,且均以有机硫化物为主,分别占总挥发性物质的82.17%和99.40%,这些硫化物对辣椒疫病菌的生长均有较强的抑制作用。这些结果表明,大葱产生的挥发性物质在辣椒疫病的绿色防控上有很好的应用前景。