Allelopathy research

An important contribution from allelopathy research may be the discovery of novel chemicals either useful as pesticides or... 

Other kinds of bloassays have been used to detect the presence of specific allelochemical effects (8), effects on N2 fIxatlon (9), the presence of volatile compounds (10) and of Inhibitory substances produced by marine microalgae (11). Putnam and Duke (12) have summarized the extraction techniques and bioassay methods used In allelopathy research. Recent developments In high performance liquid chromatography (HPLC) separation of allelochemlcals from plant extracts dictates the need for bloassays with sensitivity to low concentrations of compounds contained In small volumes of eluent. Einhellig at al. (13) described a bloassay using Lemna minor L. growing In tissue culture cluster dish wells that maximizes sensitivity and minimizes sample requirements. 

Allelopathy is newly emerging multidisciplinary field of agricultural research. A lot of allelopathy research work has been done in various fields of agriculture and plant sciences. However, standard methods are not being used by workers due to lack of a compendium on the techniques, and hence the results obtained are not easily comparable with each other. This causes problems to researchers working in underdeveloped / third world countries in small towns, where library and research facilities are not available. Therefore, to make available the standard methods for conducting allelopathy research work, this multi-volume book has been planned, with one volume each for each discipline. In all the conferences held since 1990 s a need has always been felt for a manual on allelopathy research methods. This book series aims to provide basic information about various methods to research workers, so that they can conduct research independently without the requirement of sophisticated equipments. The methods have been described in a simple way just like a DO IT YOURSELF book. 

The term allelopathy was coined by Prof. Hans Molisch, a German plant physiologist in 1937. It is a new field of science and, till now there is no Book on Methodology of Allelopathy Research. Thus causing a lot of problems to researchers working in underdeveloped/Third World countries, in small... 

Haig, T. Application of hyphenated chromatography-mass spectrometry techniques to plant allelopathy research. J Chem Ecol 2001 27 2363-2396. 

Kim K.U., Shin D.H. Rice allelopathy research in Korea. In Allelopathy in Rice. M. Olofsdotter, ed. International Rice Research Institute, Manila, Philippines, 1998 pp. 39-43. 

Mallik, A.U. Challenges and opportunities in allelopathy research a brief overview. J Chem Ecol 2000 26 2007-... 

Belz RG, Velini ED, Duke SO (2007) Dose/response relationships in allelopathy research. In Fujii Y, Hiradate S (eds) Allelopathy new concepts and methodologies. Science Publishers, Enfield, NH, pp 3-29... 

Belz RG (2007) Allelopathy in crop/weed interactions - an update. Pest Manag Sci 63 308-326 Belz RG (2008) Stimulation versus inhibition - bioactivity of parthenin, a phytochemical from Parthenium hysterophorus L. Int Dose-Response Soc 6 80-96 Belz RG, Vehni ED, Duke SO (2007) Dose/response relationships in allelopathy research. In Fujii Y, Hiradate S (eds) Allelopathy new concepts and methodologies. Science Publishers, Enfield, NH, pp 3-29... 

Indeijit et al. (2002) Joint action of phenolic acid mixtures and its significance in allelopathy research. Physiol. Plant. 114, 422-428... 

The overuse of synthetic chemicals for pest control is a threat to the environment (22-23). There is a misleading tendency that compounds produced by plants are eco>friendly. In fact, many allelopathy researchers feel that allelochemicals could be ideal agrochemicals (24-33). But we must assess the safety of these products before using allelochemicals just the same way as synthetic agrochemicals. 

How weeds produce their effect is the subject of continuing research. As rather recently defined, the negative effect of weeds on crop plants includes both competition and allelopathy (1.) and has been termed interference. Previous weed science research considered the competition component foremost and, usually, solely (e.g. 2). Allelopathy, however, has received some attention recently, with a number of symposia and reviews devoted to allelopathic effects. Some of these cover the effects of weeds on crops (3, 4, 5). In this chapter, I review the possible role of allelopathy in weed interference in crop production in the Mid-South. A second objective of this review is to indicate where research is needed and to suggest potential lines of future research, especially with respect to the developing role of conservation tillage practices in this region. 

Table I provides general information on the identified allelopathic weeds and the crops they affect. More detailed information on two of these weeds, johnsongrass and purple nutsedge, will be presented to show the tenuous nature of the evidence for allelopathy. These two species are undoubtedly allelopathic, at least under certain conditions. Rigorous proof that allelopathy is the agent responsible for even a specific portion of the interference exerted by them is not easily attained, however, even though these are the weeds with the best research data available of those weeds that occur in the Mid-South.

Future research. Ample research has been conducted to demonstrate the allelopathic potential of numerous weedy species, and of their associated crops. Future research should be directed to discerning how much of this potential is realized in the field under humid, warm conditions such as that found in the Southeast United States. Newman (33), in a reflective article, concludes that "—it cannot be said with confidence that allelopathy has any significance for agriculture." The evidence so far certainly substantiates his conclusion. To get a better feel for allelopathy in the field, field studies should minimally include the weed and weed residues. 

Others also have proposed that allelochemicals could prove useful in crcp protection, especially for minimizing the agricultural losses due to insects and nematodes, and for controlling diseases. The USDA Research Planning Conference in 1977 estimated that technological advances could reduce substantially the 30 billion in annual losses caused by pests and the cost of their control (37). This conference proposed the following strategies for research Tn allelopathy. 

Report of the Research Planning Conference on the Role of Secondary Canpounds in Plant Interactions (Allelopathy)."... 

Our research on allelopathy in tall fescue (Festuca arundinacea Schreb.) was begun to determine if growth inhibitors were present, if tall fescue had an inhibitory effect on plants growing in association with it, and finally to identify the chemicals responsible for inhibition. 

Once biological activity has been established (in the laboratory or the field) and once the chemical work has been accomplished, we need to confirm allelopathic activity in the natural environment. To accomplish this end, the effects of soil and microbial flora must be considered. Thus, the disciplines of soil chemistry and microbiology are required. The chapters in this volume deal primarily with the biology and chemistry of phytotoxins isolated from plants however, we hope that these topics will stimulate soil chemists and microbiologists to contribute to solving the problems associated with the study of allelopathy. Thus, the purpose of this volume is not only to bring before the scientific community a representation of research efforts in the area of allelopathy, but also to promote the relationships... 

Professor Emeritus Department of Biochemistry and Molecular Biology Oklahoma State University Room 246, Noble Research Center Stillwater, OK 74078 Foundation President International Allelopathy Society E-mail gwaller biochem.okstate.edu... 

Continuous culture systems have been widely used to culture microorganisms for industrial and research purposes (Kubitschek 1970 Tempest 1970 Veldkamp 1976 Rhee 1980). In recent years, these culture techniques have found their way into the bioassay methods of ecotoxicology and allelopathy (Rhee 1980). The early development of a continuous culture system can be traced back to the work of Novik and Szilard (1950 a,b) who developed the first chemostat. In a continuous culture system, nutrients are supplied to the cell culture at a constant rate and to maintain a constant volume, an equal volume of cell culture is removed. This allows the cell population to reach a steady state, where the growth rate and the total number of cells/ml of culture remains constant. Two kind of continuous culture systems can be distinguished turbidostat and chemostat. ... 

Although this chapter may not provide complete and final synthesis of the subject, our hope is that the information presented can stimulate young researchers to expand both the depth and breath of microscopy in allelopathy. 

Baranenko, V.V. (2001). Pea chloroplasts under clino-rotation lipid peroxidation and superoxide dismutase activity. Advances in Space Research 27 973-976. Bhowmik, P.C. and Inderjit (2003). Challenges and opportunities in implementing allelopathy for natural weed management. Crop Protection 22 661-671. 

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