蒲公英水提液对几种植物的化感作用

采用培养皿滤纸法,以反枝苋（Amaranthus retroflexus L．）、番茄（Lycopersicon esculentum Miller．）、生菜（Lactuca sativa L．var．ramosa Hort）、小白菜（Brassica rapa L．Chinensis Group）和小麦（Triticum aestivum L．）5种植物为受试植物,对蒲公英（Taraxacum mongolicum）水提液的化感作用进行了测定。结果表明,蒲公英水提液对5种植物种子的萌发均有一定的抑制作用。当浓度为0．1g／ml时,对5种植物种子萌发的抑制率均为100％,随着浓度降低,对种子萌发的抑制率减小。当浓度为0．1、0．05、0．025g／ml时,对5种植物根的生长、茎的生长均有一定抑制作用。当浓度为0．0125g／ml时,对反枝苋、番茄和生菜的幼苗茎生长有抑制作用,而对小白菜和小麦幼苗茎生长有促进作用。     

小麦化感作用物的提取,分离及其对白茅的杀除效果

小麦颖壳提取物经3520树脂分离后,对所得甲醇洗脱物离心,分得油类似物、上清液及沉淀物。前两个组分在300mg/L的浓度下,对白茅生长抑制率分别为100％和98％。上清液经硅胶柱分离,得7个亚组分,其中第1、3和7号亚组分在500mg/L浓度下对白茅生长的抑制率分别为95％、91％和95％。第3亚组分经葡聚糖凝胶柱分离,又分得A、B、C 3个组分,褐色粉末状的B组分在1000mg/L浓度下使白茅的生长量下降81％。从而证明小麦颖壳对白茅的化感作用是由多个化感物共同作用的结果。室内和温室及大田的测定结果表明,小麦颖壳中的甲醇洗脱物在24mg/株的剂量下对白茅生长的抑制率可达90％以上。这暗示,小麦颖壳中的甲醇可溶物可望开发成为防治白茅的生物除草剂。     

油菜对千金子的化感作用及其化感物质分离鉴定

研究了油菜茎根水提液对后茬稻田中恶性杂草千金子的化感作用,并分离鉴定了化感物质。结果表明,不同品种油菜的水提液对千金子种子萌发有抑制作用,对幼苗生长无影响,同时对水稻种子萌发及幼苗生长安全。利用室内生测及GC-MS方法鉴定抑制千金子种子萌发的化感物质为有机酸,抑制率达100%。其主要成分为油酸、棕榈酸、芥酸、亚油酸、硬脂酸、二十碳烯酸及山嵛酸。     

西芹醇层物对黄瓜枯萎病菌的化感作用及化感物质鉴定

枯萎病是黄瓜栽培过程中较为严重的真菌病害,目前对该病防治非常困难。生产中发现西芹与黄瓜轮作能够降低黄瓜枯萎病的发病率。为探明西芹鲜根中对黄瓜枯萎病菌F.oxysporum f.sp.cucumerinum有抑制作用的化感物质成分,利用连续柱层析法对西芹鲜根乙醇浸提液进行了4次柱层析,每次层析后获得的流分与黄瓜枯萎病菌共培养,测定菌落直径并计算其化感效果,以化感抑制效果筛选最佳流分;然后将最佳流分与黄瓜枯萎病菌在液体培养基中共培养,测定其菌体分泌的镰刀菌酸的含量;最后对第4次层析最佳流分进行GC-MS检测。结果表明,第4次层析最佳流分作用于黄瓜枯萎病菌后,对其菌落生长及分泌镰刀菌酸的能力均产生抑制作用;化感效果分别达到了54.59%、52.35%、51.55%和50.97%,镰刀菌酸含量下降到38.09%、59.54%、36.78%和36.65%;第4次层析最佳流分中,共鉴定出酸类、酯类、酚类、醇类及含氮化合物等5类16种化感物质,分别为十六烷基胺、16-甲基十七烷酸甲酯、十六酸、2,4-二甲基-苯并[b]喹啉、D-异薄荷醇、2,6-二叔丁基对甲酚、α-阿拉伯呋喃糖苷、硬脂醇乙酸酯、9,12-十八碳二烯酸、2-羟基丙酸、顺-9-十六(碳烯酸)、月桂酸乙酯、芴-2-偶氮-2,4-二羟基苯、甘露糖醇月桂酸酯、薄荷呋喃、4-甲氧基水杨酸。研究获得的结果可为西芹提取物防控黄瓜枯萎病提供理论依据。     

蟛蜞菊对华南地区部分农田杂草化感作用的研究

研究了蟛蜞菊（Wedlia chinensis Merr.)对异型莎草（Cypers difformis L.)雀稗草（Paspalum thunbrgii kunth Exsteud)、莲子草（Alternanthera sessilis DC.)，狗牙根草（Cynodon doacylon Pers.)等杂草种子萌芽和生长的影响。结果表明，经蟛蜞菊浸液处理的杂草种子发芽率降低，植株生长势弱，叶子枯黄，植株抵抗力下降，出现病虫害，蟛蜞菊不同器官的浸提液对杂草种子萌芽、生长的影响症状相同，但影响程度却各不相同，效果明显程度依次是：叶片＞茎＞植株＞根。     

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.     

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。     

银胶菊的花对小麦的化感作用机制

采用温室盆栽法,研究了银胶菊的花水浸提液对小麦生长及其生理生化机制的影响,以明确其对小麦的化感作用。结果显示,花水浸提液抑制小麦种子萌发和幼苗生长,且抑制强度随浸提液浓度的升高而加强;随着花水浸提液浓度的增加,小麦叶片光合作用、光合色素含量和过氧化氢酶(CAT)活性下降,磷(P)和丙二醛(MDA)含量升高,氮(N)含量呈现先降低后趋于正常的变化趋势,硝酸还原酶(NR)活性呈现先降低后升高的变化趋势,谷氨酰胺合成酶(GS)活性没有显著变化,而过氧化物酶(POD)和超氧化物歧化酶(SOD)活性则呈现先升高后降低的变化趋势。表明银胶菊的花水浸提液抑制小麦叶片光合作用,提高了小麦叶片的MDA含量,并降低了小麦叶片SOD、POD和CAT的活性。     

小麦植株水提液对升马唐的化学他感作用研究初报

本文通过研究小麦植株水提液对升马唐 (Digitariaciliaris)种子发芽及幼苗生长的影响 ,初步明确小麦对升马唐种子发芽存在他感作用 ,其作用程度因小麦品种不同而有差异。植株的不同部位、不同生育期及水提液不同浓度对升马唐种子发芽的抑制作用是不一样的     

Studies on competition between wheat and Chenopodium album L.

Interspecific competition between wheat (Triticum aestivum L.) and Chenopodium album L., was studied in pots using the replacement series design of de Wit. Competitive interference for phosphorus, and to some extent for nitrogen, between the two species was noted. This played a major part in limitation of growth of wheat plants by C. album, whereas wheat exhibited greater non-competitive interference in restricting potassium uptake by the weed. Increasing interference from the weed resulted in significant reductions in wheat grain size and yield.     

Possible rôle of allelopathy in the competition between tomato, Senecio vulgaris L. and Chenopodium album L.

Summary. The allelopathic effect of Chenopodium album L. (fat-hen) and Senecio vulgaris L. (groundsel) on tomato ( Lycopersicon esculentum Mill cv. Ailsa Craig) plants was investigated under glasshouse conditions. A new technology was used to separate competitive from allelopathic effects. These experiments suggested that C. album had an effect on tomato through allelopathy. C. album leach-ates significantly reduced shoot fresh and dry weights and the accumulation of N, P, K, Ca and Mg of tomato shoots. No effect was found on the quantities of these elements in tomato roots. Leachate of five plants of C. album per pot was sufficient to reduce tomato growth. Addition of 10 or 20 g kg⁻¹ of C. album dried shoots to the soil mixture significantly decreased the fresh and dry weights of tomato plants. S. vulgaris leachates did not show significant effects on the growth or nutrient accumulation of tomato plants.     

Paraquat-resistant biotypes of Hordeum glaucum from zero-tillage wheat

There has been a significant increase in the area seeded to minimum- and zero-tilled crops worldwide over the past two decades. These cropping systems rely primarily on the non-selective herbicides glyphosate or paraquat/diquat to control weeds before seeding the crop. Both glyphosate and paraquat/diquat are regarded as low-risk herbicides in the ability of target weeds to develop resistance to them. Following 10–15 years of once annual applications of paraquat and diquat for weed control in zero-tilled cereals, failure of these herbicides to control Hordeum glaucum Steud. in two separate fields occurred. Dose–response experiments demonstrated high-level resistance to paraquat and diquat in both populations; however, the resistant biotypes are susceptible to other herbicides. This is the first report, worldwide, of paraquat resistance following the use of this herbicide in zero-tillage cropping systems and is therefore a harbinger of future problems in minimum-tillage systems when there is exclusive reliance on a contact herbicide for weed control.     

加拿大一枝黄花浸出液对杂草种子发芽的影响

加拿大一枝黄花的鲜根茎和鲜叶片分别用2种方法获取浸出液，并制成不同浓度，分别对日本看麦娘、小藜、旱稗、马唐、狗草尾、鳢肠和凹头苋等7种杂草种子进行发芽率测定。结果表明，浸出液对7种杂草种子的发芽势和发芽率均有明显的抑制作用。鲜根茎和鲜叶片的组织粉碎抽滤液的影响要大于鲜根茎和鲜叶片的水浸液。鲜叶片组织粉碎抽滤液的不同浓度对杂草种子发芽的影响不同，浓度越高影响越大。     

Mulberry leaf water extract inhibits bermudagrass and promotes wheat growth

Allelopathy has the potential to tackle the concerns associated with the indiscriminate use of synthetic herbicides. In search of a natural herbicide, the effects of mulberry (Morus alba) leaf water extracts on bermudagrass (Cynodon dactylon) and wheat (Triticum aestivum) were investigated. Four concentrations of extract (25, 50, 75, and 100%) were compared with a control (distilled water). The results revealed that the pregermination application of 100% mulberry leaf water extract resulted in the complete inhibition of bermudagrass and wheat germination. However, postemergence, two foliar sprays suppressed only the growth of bermudagrass and promoted wheat growth. The effect of the mulberry leaf water extract was concentration dependent. It is evident that the postemergence application of mulberry leaf water extract has the scope for use as natural herbicide for the control of bermudagrass and to promote the growth and yield of wheat.     

蜈蚣草提取物杀虫活性初步研究

采用触杀法和拒食法测定了蜈蚣草甲醇粗提物和石油醚、三氯甲烷、乙酸乙酯、正丁醇4种溶剂萃取物对莴苣指管蚜和斜纹夜蛾的杀虫活性.结果表明,三氯甲烷萃取物对两种害虫具有较高的杀虫活性.莴苣指管蚜随着提取物质量浓度的增大和处理时间的延长,其校正死亡率升高.质量浓度为10 mg/mL时,莴苣指管蚜72h的校正死亡率达到86.92％,LC50为1.724 2 mg/mL;斜纹夜蛾4龄幼虫24h的非选择性拒食率为65.76％,AFC50为3.934 6 mg/mL.     

紫茎泽兰化感作用研究

有紫茎泽兰生长与无紫茎泽兰生长的土壤中,一年生黑麦草、多年生黑麦草、紫花苜蓿和光叶紫花苕的出苗率、株高和鲜重均无显著性差异;紫茎泽兰水培液与清水比较,无论是盆栽还是培养皿生长试验,4种牧草的成活率、株高和鲜重无显著性差异。由此得出：紫茎泽兰对4种牧草的生长无明显的化感作用。     

Environmental conditions and isozyme polymorphism in Chenopodium album L.

Electrophoretic variations within four enzyme systems (α-esterase, acid phosphatase, malate dehydrogenase and leucine amino peptidase), were studied for various garden and field populations of Chenopodium album. A correlation was found between the degree of polymorphism for the electrophoretic traits and environmental conditions. The amount of phenotypic polymorphism is very high in gardens, intermediate in an untreated and, low in herbicide-treated fields and nil for a triazine resistant population in a maize (Zea mats L.) monoculture. Furthermore, the tetraploid versus hexaploid ratio is higher within garden populations. Higher variability in garden populations is due, in part, to a high proportion of polymorphic phenotypes, and in part to a low effect of selection pressure in such types of habitat. Although there is a difference between phenotypes of populations from acid soils and those from more basic ones, we cannot be sure that the variation of polymorphism is due only to selection.     

Differential atrazine interference with the Hill reaction of isolated chloroplasts from Chenopodium album L. biotypes

Atrazine [2-chloro-4-(ethylaminol-6-(isopropyl-amino)-s-triazine] resistant biotypes of lamb's quarters (Chenopodium athum L) were reported in the maize growing areas of Ontario, where the herbicide had been used fur a number of years. Field samples from four locations proved tolerant to higber than recommended rates of atrazine in controlled environment screening trials. A resistant biotype was not killed with up to 40 kg/ha atrazine. Diuron at 5 x10-5 M inhibited the Hill reaction with isolated chloroplasts of resisiant and susceptible biotypes of lamb's-quarters. However, with 10-4 M atrazine, the photochemical activity was inhibited in chloroplasts isolated from the susceptible biotype but not in chloroplasts from the resisiant biotype. With maize chloroplasts, inhibition with 10-4 M atrazine was the same as with the susceptible biotype of lamb's-quarters. These studies suggested that a new mechanism of intraspecific resistance in lamb's quarters to atrazine was involved, other than differences in uptake, translocation and metabolism reported with interspecific comparisons involving the s-triazines and other herbicides, It was also concluded that atrazine and diuron did not have precisely the same mechanism of action as photosynthetic inhibitors with lamb's-quarters, and that external and or internal structure or function of chloroplasts in relation to atrazine inhibition can vary significantly even in biotypes of the same species.     

干旱胁迫对藜叶片干旱诱导蛋白的影响

采用SDS-PA GE(十二烷基硫酸钠-聚丙烯酰胺)凝胶电泳法进行蛋白质的分离,研究干旱胁迫对藜叶片干旱诱导蛋白的影响.结果表明:干旱胁迫10 d,中度干旱藜的叶片110.3 KD和103.9 KD及24.8 KD,22.7KD,21.0 KD蛋白谱带明显加强,重度干旱胁迫下22.7 KD,21.0 KD蛋白谱带增强,但弱于中度干旱胁迫;干旱胁迫15 d,中度干旱胁迫下蛋白谱带与第10 d中度干旱胁迫下的蛋白谱带相比,26.4 KD和19.2 KD蛋白谱带增强.这说明干旱诱导了藜一些适应水分胁迫相关基因的表达,或使一些基因的表达量增强,导致一些新蛋白质的出现或某些蛋白质量的增加而增强其对干旱胁迫的抵抗能力.