化感作用及其在农业生产中的应用

简述了化感作用的概念、特点、作用机理和化感物质及释放途径。讨论了植物与植物之间,植物与微生物之间,植物与昆虫等食草动物之间的化感作用及化感理论在生产实践中的应用。应用化感理论指导建立合理的栽培、耕作制度;进行田间杂草生物控制和防治;开发新一代无公害农药;指导森林更新和建植;培育抗化感品种等。     

豚草的化感作用研究

本文研究了在我国东北地区广泛蔓延的菊科杂草－－豚草对大豆、玉米、小麦、水稻的化感作用,实验针对豚草的挥发物、茎叶和根的淋溶物、根区土壤水浸液等的化感活性进行了研究,研究发现豚草的挥发物对大豆和玉米的种子萌发有一定抑制作用,根区土壤对农作物无明显的作用;茎叶部分的水浸液对几种农作物的种子萌发和幼苗的幼根伸长有明显的抑制作用,同时使根系形态发生较大的变化,根系的水浸液对作物的幼芽伸长有一定的促进作用。     

胜红蓟化感作用研究 Ⅷ.植株对花生和相关杂草的田间化感效应

在田间条件下,胜红蓟化感效应与处理植株的方式和时间显相关。覆盖处理对花生出苗和生长不产生化感抑制效应,而是显示一定的促进效应,翻埋处理对花生出苗和生长都产生显的化感抑制效应,然而覆盖处理30d,翻埋处理10d后再播种花生,花生出苗均受显抑制,两种处理都能减少许多杂草的萌发,但对不同种属杂草萌发的抑制作用有差异。进一步用高效液相色谱（HPLC）技术研究证实;覆盖处理条件下,胜红蓟植株直到第14天才向土壤中缓慢释放化感物质胜红蓟素,第30天达到最大值后逐渐减少,而翻埋处理的第2天,植株就向土壤中释放胜红蓟素,第10天达到最大值后缓慢减少,但第26天后土壤中胜红蓟素含量又上升,然后再逐步下降。这些结果显示不同处理条件下,胜红蓟植株对花生和相关杂草的田间化感效应是与胜红蓟植株在不同时间释放的化感物质在土壤中的存在状态和有效作用浓度显相关的。     

胜红蓟化感作用研究I.水溶物的化感作用及其化感物质分离鉴定

研究了胜红蓟水溶物对植物的化感作用,结果表明,胜红蓟水溶物溶液浓度在０．２５ｇＦＷ．ｍｌ＾－１时对所有供试植物的萌发和幼苗生长均有显著的抑制作用,浓度降至０．１０ｇＦＷ．ｍｌ＾－１时其抑制作用基本消失,胜红蓟不同器官,不同生育期水溶物的化感作用是有差异的,特别是不同生境条件下生长的胜红蓟水物化感作用有显著差异,表明在恶劣生境下胜红蓟的化感作用更为强烈,对胜红蓟水溶物中的化感活性物质进行了分离和分子     

小麦化感作用研究进展

小麦是世界第一大粮食作物,在农业生产中占有重要地位.然而,由于人们为保证小麦产量往往施用大量的除草剂和杀菌剂,对环境造成了极大的危害.小麦化感作用是利用小麦活体或残体向环境中释放次生代谢物质对自身或其他生物产生作用,它克服了除草剂和杀菌剂等引起的环境污染问题,具有抑制杂草控制病害的潜力.本文对已有的小麦化感作用的研究进展情况进行了综合评述.其中小麦对杂草、虫害及病害产生防御功能的主要化感物质为异羟肟酸和酚酸类物质.小麦化感物质活性的发挥除了取决于化感物质的种类外,还由小麦自身的遗传因素、环境因素和生物因素的共同作用所决定.小麦化感物质在根际土壤中的滞留、迁移和转化过程、小麦化感作用与土壤生物的关系以及相关的作用机理是小麦化感作用研究的薄弱环节,其研究方法还需进一步探索改进.小麦化感作用在植物保护、环境保护以及作物育种等方面具有广泛的应用前景,促进了小麦抗逆性的增强以及产量和品质的提高.     

水稻化感作用研究综述

主要对水稻化感现象发现,化感生物检测,化感物质分离和鉴定,化感种质资源等方面的研究进展了系统的综合论述,在此基础上,进一步对化感作用研究中的主要问题,例如;生物检测手段,化感作用利用途径等进行了分析。并对我国的化感作用研究的存在问题及发展方向作出了论述。     

浮游植物的化感作用

生物化感作用研究是近年来兴起的交叉学科,是化学生态学研究的重要领域。研究水域浮游植物化感作用对了解浮游植物之间、浮游植物与其他生物之间的相互作用及作用机理具有重要意义,对了解赤潮和水华的发生机制及其生态控制等具有非常重要的作用。综述了海洋和湖泊浮游植物化感作用和化感物质的内涵,讨论了水体浮游植物化感作用的特点、研究化感作用的基本方法、化感物质的种类以及影响化感物质作用的生物和非生物因素,详细介绍了浮游植物化感物质的作用机理以及逃避和拈抗化感作用的方式,同时对目前研究的热点问题及未来研究的方向做了简要概述。     

菊科植物化感作用研究进展

对菊科植物化感作用的研究进展进行了综述。菊科植物中至少有 39个属存在化感作用 ,特别是一枝黄花属、向日葵属、胜红蓟属、银胶菊属、蒿属植物等有较多的研究报道。鉴定出的化感物质多为萜类、聚乙炔类、酚类、有机酸类等 ,这些化感物质对多种受体植物表现出程度不同的抑制或促进的效应。其化感作用机理表现在破坏受体膜系统的稳定性及水分平衡关系、抑制氧化磷酸化、促进或阻滞叶绿素的合成、影响矿质元素的吸收利用等。并对菊科植物化感物质在植物生长调节剂、天然除草剂和生物杀虫剂 ,或人工合成除草剂和杀虫剂上应用的前景进行了探讨。本文显示菊科植物的化感作用将在控制外来恶性杂草及维护生态平衡上扮演重要的角色。在当前菊科植物化感作用研究的基础上 ,提出了进一步研究的 6个方向 :(1)化感物质的生物合成途径与关键酶的特性研究 ;(2 )具化感潜势物种资源的调查评价及利用研究 ;(3)化感作用在自然生态系统中的演变规律 ;(4 )菊科重要作物自毒的生化机制及克服途径 ;(5 )具应用前景的菊科植物化感关键酶的基因克隆和转基因 ,并对受体植物基因的表达与调控进行研究 ;(6 )化感作用在可持续发展农业应用上的研究与开发 ,特别是作为天然除草剂及杀虫剂     

苜蓿化感作用研究进展

苜蓿是一种优良的多年生豆科牧草 ,具有多重生态功能 ,在世界范围内广泛种植。苜蓿在第 2～ 4年后产量逐渐下降 ,而且种过苜蓿的土壤 ,间隔较短时间再种苜蓿 ,很难建植成功。许多研究表明 ,苜蓿体内含有的一些水溶性化学物质不仅能够对其产生自毒作用 ,而且也能对其他植物具有化感作用。本文综述了苜蓿化感作用研究进展 ,包括苜蓿中主要的化感物质、影响苜蓿化感作用的因素、苜蓿化感作用的应用三个方面。同时就苜蓿化感作用今后的研究重点提出一些看法和展望。     

Algal allelopathy

The comprehensive review on allelopathy (Rice, 1979, 1984) has been largely responsible for the evolution of allelopathy as an independent branch of chemical/ physiological ecology. The allelopathic research during the last four decades drew attention to different facets of the interactions among the constituents of habitat, calling for an understanding of the role of allelopathy under different habitat conditions. In view of this, we have reviewed the existing information on allelopathic interactions in aquatic habitats with special reference to algal allelopathy. This review has been mainly confined, therefore, to different aspects of algal allelopathy such as allelopathic interactions in algae, algal toxins, bioassays, and implications of algal allelopathy. In spite of the large number of reviews on allelopathy (see section III), no independent review appears on algal allelopathy. Although there were reports of toxins from cyanobacteria and other algae, no appreciable attempt was made to implicate algal toxins in allelopathy under field conditions. Knowledge of chemistry and biology of allelochemical can help in their potential use in controlling plant diseases and weeds. Therefore, it is urgent to study algal toxins for their involvement in ecological phenomena such as succession, for their uses as herbicides, weedicides, and pesticides, for their uses in solving some of the problems of algal ecology, and for their involvement in applied aspects.     

The ecosystem and evolutionary contexts of allelopathy

Plants can release chemicals into the environment that suppress the growth and establishment of other plants in their vicinity: a process known as 'allelopathy'. However, chemicals with allelopathic functions have other ecological roles, such as plant defense, nutrient chelation, and regulation of soil biota in ways that affect decomposition and soil fertility. These ecosystem-scale roles of allelopathic chemicals can augment, attenuate or modify their community-scale functions. In this review we explore allelopathy in the context of ecosystem properties, and through its role in exotic invasions consider how evolution might affect the intensity and importance of allelopathic interactions.     

Ecophysiological aspects of allelopathy

Allelochemicals play an important role in explaining plant growth inhibition in interspecies interactions and in structuring the plant community. Five aspects of allelochemicals are discussed from an ecophysiological perspective: (i) biosynthesis, (ii) mode of release, (iii) mode of action, (iv) detoxification and prevention of autotoxicity, and (v) joint action of allelochemicals. A discussion on identifying a compound as an allelochemical is also presented.     

Biochemical frontiers of allelopathy

Allelopathic interactions between plants and other organisms have been recognized by scientists worldwide because they offer alternative uses in agriculture, such as decreasing our reliance on synthetic herbicides, insecticides, and nematicides for disease and insect control. The recognition of the role that allelopathy can have in producing optimum crop yields is of fundamental importance. Despite much optimism and some progress in unravelling the complexities of biochemical interactions between species, a firm foundation for the scientific rationale of the existence and function of the allelopathic phenomenon has not been developed. Allelopathic chemicals are primarily secondary products of plant metabolism which have been an enigma to plant scientists; however, they undergo a variety of reactions with plant, insect and animal species that inhibit or stimulate their growth and development. Examples of some allelochemicals and their basis of molecular and biological action are shown: interaction between the unicorn plant (Proboscidea louisianica L.) and cotton (Gossypium hirsutum L.); diterpenoid alkaloids (fromDelphinium ajacis L.) as allelochemicals; substances that occur in wheat (Tritcum aestivum) and wheat soil that cause autotoxic effects; alfalfa (Medicago sativa L.) root saponins as allelochemicals; humic acids from wheat soil as allelochemicals; and structure-function of flavonols serving as allelochemicals in chloroplast-mediated electron transport and phosphorylation. This paper concludes with a discussion of some frontier areas of research in allelopathy.     

Plant phenolics in allelopathy

Phenolics are one of the many secondary metabolites implicated in allelopathy. To establish that allelopathy functions in a natural ecosystem, the allelopathic bioassay must be ecologically realistic so that responses of appropriate bioassay species are determined at relevant concentrations. It is important to isolate, identify, and characterize phenolic compounds from the soil. However, since it is essentially impossible to simulate exact field conditions, experiments must be designed with conditions resembling those found in natural systems. It is argued that allelopathic potential of phenolics can be appreciated only when we have a good understanding of 1) species responses to phenolic allelochemicals, 2) methods for extraction and isolation of phenolic allelochemicals, and 3) how abiotic and biotic factors affect phenolic toxicity.     

An ecosystem-level perspective of allelopathy

Allelopathy is an interference mechanism by which plants release chemicals which affect other plants; while it has often been proposed as a mechanism for influencing plant populations and communities, its acceptance by plant ecologists has been limited because of methodological problems as well as difficulties of relating the results of bioassays used for testing allelopathy to vegetation patterns in the field. Here we argue that the concept of allelopathy is more appropriately applied at the ecosystem-level, rather than the traditional population/community level of resolution. Firstly, we consider the wide ranging effects of secondary metabolites (widely regarded as allelochemicals) on organisms and processes which regulate ecosystem function, including herbivory, decomposition and nutrient mineralization. It is apparent that plants with allelopathic potential against other organisms induce net changes in ecosystem properties, which may in turn impact upon the plant community in the longer term. We then illustrate these concepts using two contrasting examples of how invasive plant species with allelopathic potential may alter ecosystem properties through the production of secondary metabolites, i.e. Carduus nutans (nodding thistle) in New Zealand pastures and Empetrum hermaphroditum (crowberry) in Swedish boreal forests. In both cases the production of secondary metabolites by the invasive species induces important effects on other organisms and key processes, which help determine how the ecosystem functions and ultimately the structure of the plant community. These examples help demonstrate that the concept of allelopathy is most effectively applied at the ecosystem-level of resolution, rather than at the population-level (i.e. plant-plant interference).     

The ecological importance of insect frass: allelopathy in eucalypts

Our previously published experiments on allelopathic effects of insect frass in Eucalyptus communities (Silander et al. 1983) have been criticized on the grounds that our estimates of annual frass production were exscessive (Ohmart 1985). However, we spanned the entire array of estimates of frass fall available from eucalypt communities, and we demonstrated allelopathic effects at even the lowest levels suggested by Ohmart. We suggest that average values of frass fall per hectare are irrelevant because they ignore both large scale variation among sites in time and space, and small scale variation in patchiness of frass accumulation. At the ecological scales relevant to germinating seeds, frass concentrations in local pockets may be considerably higher than the averages calculated for the entire ground surface.     

The role of allelopathy in biochemical ecology: Experience from Taiwan

Allelopathic compounds, including fatty acids, phenolics, flavonoids, terpenoids, and alkaloids, have been found in various plants and soils of different habitats in Taiwan since 1972. For example, in a monoculture of rice plants, phytotoxins were produced during the decomposition of rice residues in soil, suppressed the growth of rice seedlings, and reduced the numbers of tillers and panicles, leading to yield reduction. The allelopathic metabolites are also affected by environmental factors, such as oxygen, temperature, soil moisture, microbial activity, and levels of fertilizers in soil, and allelopathy was pronounced in areas where environmental stresses were severe. Substantial amounts of phytotoxic mimosine and phenolics were released into soil by plant parts of Leucaenaleucocephala, and these suppressed the growth of many understory species except that of L.leucocephala itself. A unique pattern of absence of understory plants was ubiquitous beneathPhyllostachys edulis, due primarily to an allelopathic effect. In a forest pasture intercropping, an aggressive kikuyu grass was planted in a deforested land where Chinese fir grew previously, to help in understanding the mechanism of biological interactions between plants. Aqueous soil leachate and extracts of the grass significantly, retarded the growth of local weeds but not that of the Chinese fir. Allelopathy thus plays an appreciable role in natural vegetation and plantations in Taiwan.     

On laboratory bioassays in allelopathy

Allelopathy involves the complex chain of chemical communications among plants, including microbes. Laboratory bioassays constitute a significant part of allelopathic research, and various bioassays have been proposed to demonstrate allelopathy under controlled lab conditions. However, many lab bioassays have little or no correspondence to field interaction, which may be due to dissimilarity of the conditions of lab bioassay to natural conditions, lack of standardized techniques, or absence of critical controls. Here we discuss several lab bioassays presently used in allelopathic research for their suitability to demonstrate allelopathy of ecological relevance. We recommend avoiding certain practices, such as grinding plant material to evaluate allelopathic potential and isolation of allelochemicals, using seed germination as the only criterion of growth response, using sand, agar, or autoclaved soil, using organic solvents as extractants in allelopathic bioassays, and eliminating microbial involvement. Care should be taken in the lab to simulate natural conditions and attention should be given to habit, habitat, and life cycle pattern of the allelopathic plants during designing of lab bioassays.