Title: Methods to screen allelopathic accessions of wheat, barley, oat, sorghum and cucumber for weed control

Author(s): Khanh TD, Xuan TD, Hahn SJ, Chung IM

Source: ALLELOPATHY JOURNAL 14 (2): 145-165 OCT 2004

Abstract: Wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), oats (Avena saliva L.), sorghum (Sorghum bicolor L.) and (cucumber (Cucumis sativus L.) are major food crops in many countries. Weeds cause serious yield losses in many crops, hence, to eradicate them, the overuse of herbicide and agrochemicals have caused environmental contamination, unsafe farming products and human health concerns. The allelopathic activities of numerous crops have been evaluated against weeds or other crops. Therefore, crop cultivars with improved allelopathic activities may be part of the future weed management strategy. This review, describes the methods to screen wheat, barley, oats, sorghum and cucumber accessions in laboratory, greenhouse and field studies for suppression of weed spp. It aims to use strong allelopathic potential of potent accessions for eco-friendly weed management.

Author Keywords: allelopathic activity; barley; cucumber; oat; sorghum; weed management; wheat

KeyWords Plus: RYEGRASS LOLIUM-RIGIDUM; CULTIVARS; SUPPRESSION; PERSISTENCE; VARIETIES; GERMPLASM; RESIDUES; EXTRACTS; SATIVUS

Addresses: Chung IM (reprint author), Konkuk Univ, Res Team Friendly Environm Low Input Nat Herbicid, Seoul, 142701 South Korea
　

Title: Allelopathic plants. XVI. Artemisia species

Author(s): Ferreira JFS, Janick J

Source: ALLELOPATHY JOURNAL 14 (2): 167-175 OCT 2004

Abstract: The allelopathic effects of Artemisia annua, A. californica, A. princeps var. orientalis, A. tridentata, and A. vulgaris are reviewed. Naturally produced allelopathic compounds that reach target species via natural methods of dissemination (air, soil, and rain) are emphasized. Possible modes of action for allelopathic compounds synthesized by Artemisia species are discussed.

Author Keywords: allelopathy; Artemisia annua; A. californica; A. princeps; A. tridentala; A. vulgaris; secondary metabolites

KeyWords Plus: METHYL JASMONATE; ANNUA; CALIFORNICA; GERMINATION; SUBSTANCES; ORIENTALIS; SAGEBRUSH; TOBACCO; ACT

Addresses: Ferreira JFS (reprint author), Purdue Univ, Dept Hort & Landscape Architecture, 1165 Hort Bldg, W Lafayette, IN 47907 USA; USDA, ARS, Appalachian Farming Syst Res Ctr, Beaver, WV 25813 USA

E-mail Addresses: jorge.ferreira@ars.usda.gov, janick@purdue.edu

Title: The insecticidal activity of saponins from various Medicago spp. against Colorado potato beetle, Leptinotarsa decemlineata Say

Author(s): Szczepanik M, Bialy Z, Jurzysta M

Source: ALLELOPATHY JOURNAL 14 (2): 177-185 OCT 2004

Abstract: The total saponins originating from the roots and shoots of three Medicago species (M. arabica, M. hybrida and M. murex) included in the diet of Colorado potato beetle larvae, reduced their feeding, growth rate and survival. The insecticidal activity of these compounds was closely correlated with the dose. All saponins applied at 0.5% concentration, showed a high insecticidal activity, but saponins from M. murex roots and from aerial parts of M. arabica and M. hybrida were especially active. The growth rate and mortality of the larvae when the saponsis fed at lower dose (0.1%) were similar to control group.

Author Keywords: Colorado potato beetle; Leptinotarsa decemlineata; Medicago arabica; Medicago hybrida; Medicago murex; saponins; secondary plant compounds

KeyWords Plus: ALFALFA SAPONINS; AERIAL PARTS; RESISTANCE; MOTH

Addresses: Szczepanik M (reprint author), Inst Soil Sci & Plant Cultivat, Dept Biochem & Plant Qual, Czartoryskich 8, Pulawy, PL-24100 Poland
E-mail Addresses: mszczep@biol.uni.torun.pl

Title: Oxidative burst and lipoxygenase activity induced by hydroxycinnamic acids in cucumber roots

Author(s): Politycka B, Bednarski W

Source: ALLELOPATHY JOURNAL 14 (2): 187-196 OCT 2004

Abstract: Seven-day-old seedlings of cucumber (Cucumis sativus L.) cv. 'Dar' were exposed to allelochemical stress by treating their roots with 0.5_mM solutions of ferulic and p-coumaric acids. In cucumber roots, the level of active oxygen species (hydrogen peroxide, superoxide anion and hydroxyl radical) and stable free radicals as well as lipoxygenase activity (in soluble and membrane bound fraction) were investigated. It was found that ferulic and p-coumaric acids caused a significant increase in the level of hydrogen peroxide and hydroxyl radical and enhanced the level of stable free radicals. Moreover, the induction of lipoxygenase activity was observed as a stress effect. The results indicate that the oxidative burst in cucumber roots occurred under the influence of ferulic and p-coumaric acids.

Author Keywords: active oxygen species; allelopathy; cucumber; Cucumis sativus L.; electron paramagnetic resonance; free radicals; lipoxygenase; oxidative burst

KeyWords Plus: SIGNAL-TRANSDUCTION; BENZOIC-ACIDS; STRESS; OXYGEN; ETHYLENE; PLANTS; POLYPHENOLS; DERIVATIVES; INFECTION; PHENOLICS

Addresses: Politycka B (reprint author), Polish Acad Sci, Inst Mol Phys, Smoluchowskiego 17, Poznan, PL-60179 Poland; August Cieszkowski Agr Univ, Poznan, PL-60637 Poland

E-mail Addresses: barpolit@jay.au.poznan.pl

Title: Is allelopathy a driving force in forest succession?

Author(s): Peng SL, Chen ZQ, Wen J, Shao H

Source: ALLELOPATHY JOURNAL 14 (2): 197-204 OCT 2004

Abstract: Allelopathy is a major research subject in chemecology, it studies the relationships between the biology and abiotic environment. Since 1960s, several scientists have studied the allelopathy in relation to plant ecology. Now most researches are being done on herbaceous plants and few on woody plants, because of their long lifecycle and slow response to allelopathic substances. Hence, we studied the dynamics and role of allelopathy in forest ecosystem. The traditional ecological theory states that the main driving forces in forest succession are light and water. However, our results of more than 20 years of fieldwork on six major tree species (Cryptocarya chinensis, Cryptocarya concinna, Schima superba, Castanopsis chinesis, Caryota ochlandra and Castanopsis fissa) of Dinghu mountain showed that a) all these test species contain allelochemicals, b) allelopathy affects the succession among these species and c) allelopathy play important role in forest succession. Thus we put forward a hypothesis that allelopathy, light and water, may be considered as the major driving forces in tropical and sub-tropical forest succession.

Author Keywords: allelopathy; cabbage Castanopsis chinesis; Castanopsis fissa; Caryota ochlandra; Cryptocarya chinensis; Cryptocarya concinna; cucumber; forest; Pinus massoniana; radish; Schima superba; succession

Addresses: Peng SL (reprint author), Zhongshan Univ, Dept Life Sci, Guangzhou, 510275 Peoples R China; Zhongshan Univ, Dept Life Sci, Guangzhou, 510275 Peoples R China

E-mail Addresses: slpeng@scib.ac.cn

Title: Effect of sorghum extract on management of barnyardgrass in rice crop

Author(s): Irshad A, Cheema ZA

Source: ALLELOPATHY JOURNAL 14 (2): 205-212 OCT 2004

Abstract: To control weeds using allelopathic properties is a new approach to avoid the use of hazardous herbicides. A 2-years field study was done to develop an environmentally safe method to control barnyard grass (Echinochloa crus-galli (L.) Beauv) in rice (Oryza sativa L.) crop. Minimum barnyard grass density and dry mass was observed with chemical control (Butachlor pre-em. @ 1.2 kg a.i. ha(-1)) followed by hand weeding (20 days after transplanting). Sorghum (Sorghum bicolor L.) water extract (SWE) significantly reduced the barnyard grass dry mass (37-41%) as compared to weedy check. Butachlor, hand weeding and one SWE increased the rice grain yield by 35.9%, 30.9% and 20.1%, respectively over unweeded check. Simple regression analysis showed that grain yield was positively associated with the number of panicle bearing tillers, number of spikelets per panicle, 1000-kernel weight, leaf area index and was negatively correlated with barnyard grass dry mass. SWE spray proved most economical and this provides base for its use as natural weedicide in rice.

Author Keywords: allelopathy; bamyardgrass; Echinochloa crus-galli; Oryza sativa; rice; Sorghum bicolor

Addresses: Irshad A (reprint author), Rice Res Inst, Lahore, 39018 Pakistan
Univ Agr Faisalabad, Dept Agron, Faisalabad, 38040 Pakistan

E-mail Addresses: aamer_irshad@yahoo.com

Title: Effects of aqueous leaf extracts of Eucalyptus globulus on germination and seedling growth of potato, maize and bean

Author(s): Malik MS

Source: ALLELOPATHY JOURNAL 14 (2): 213-219 OCT 2004

Author Keywords: allelochemicals; bioassay; butter bean; Eucalyptus globulus; maize; Phaseolus lunatus; potato; Solanum tuberosum; Zea mays

KeyWords Plus: PLANTS

Addresses: Malik MS (reprint author), SK Univ Agr Sci & Technol, Div Forestry, Jammu, 191121 India
　

Title: Allelopathic effects of leaf loppings of multipurpose trees and cashewnut shell liquid to control coconut root grub (Leucopholis coneophora Bur.)

Author(s): John J, Sreekumar KM, Rekha P, Abhilash EK

Source: ALLELOPATHY JOURNAL 14 (2): 221-226 OCT 2004

Author Keywords: Ailanthus triphysa; allelopathy; Anacardium occidentale; Artocarpus heterophyllus; cashew nut shell liquid; Casuarina equisetifolia; Coconut; Gliricidia sepium; leaf lopping; Leucopholis coneophora; Mangifera indica; root grub; Strychnos nux-vomica; Tamarindus indica; Tectona grandis; Thespesia populnea; Vigna unguiculata

Addresses: John J (reprint author), Kerala Agr Univ, Coll Agr, Kasaragod, Kerala 671328 India
E-mail Addresses: jjkau@rediffmail.com

Title: Biocidal potential of leaf extracts of Vitex negundo Linn.

Author(s): Kaushik RD, Sharma G, Arora C

Source: ALLELOPATHY JOURNAL 14 (2): 227-233 OCT 2004

Author Keywords: Bacillus megatrium; biocidal potential; Escherichia coli; leaf extracts; Mycogone perniciosa; n-pentatriacontane; Pseudomonas fluorescence; Rhizocionia solani; Sarcina lutea; Staphylococcus spp.; Vitex negundo L. and Xanthomonas spp.

KeyWords Plus: FUNGAL PATHOGENS; PLANTS; SEEDS

Addresses: Kaushik RD (reprint author), Gurukul Kangri Univ, Dept Chem, Haridwar, 249404 India
E-mail Addresses: rduttkaushik@yahoo.co.in

Title: Allelopathic plants. XV. Ageratum conyzoides L.

Author(s): Kong CH, Hu F, Xu XH, Liang WJ, Zhang CX

Source: ALLELOPATHY JOURNAL 14 (1): 1-12 JUL 2004

Abstract: The genus Agertum-consists of about 40 spp. found in tropical and subtropical countries, however, only two spp. A. conyzoides L. and A. houstonianum Mill are well known. The allelopathy of only Ageratum conyzoides L. has been studied in bioassays, pot cultures and field investigations. Its allelopathic potential varied with growth stages and environmental conditions. It releases more volatile allelochemicals (ageratochromene and its derivatives, monoterpenes, sesquiterpenes and flavones) under adverse conditions. These allelochemicals not only inhibited the germination and growth of associated plants, but also adversely affected the microbes and insects. Intercropping of Ageratum conyzoides in citrus orchards effectively suppressed the weeds and controlled other insect pests, hence, practiced in large areas in South China. Besides, the mode of release, transformation in soils of major allelcochemicals front A. conyzoides has been studied.

Author Keywords: ageratochromene; Ageratum conyzoides; allelochemical allelopathy; chemical interactions; citrus orchard; flavones; pathogens; terpenes; weeds

KeyWords Plus: ESSENTIAL OIL; RICE YIELD; WEEDS; GERMINATION; CONSTITUENTS; PRECOCENES; EXTRACTS; GROWTH

Addresses: Kong CH (reprint author), S China Agr Univ, Inst Trop & Subtrop Ecol, Guangzhou, 510642 Peoples R China
E-mail Addresses: chkong@scau.edu.cn

Title: Sorption of crop residue-derived dissolved organic matter by soils and its effect on allelopathic expression

Author(s): Ohno T, Chen P, Jefts SS, Mallory E, McCormick EK

Source: ALLELOPATHY JOURNAL 14 (1): 13-21 JUL 2004

Abstract: Our previous studies have shown that legume green manures may contribute to weed control through allelopathy. The objectives (if this study were to investigate the sorption reaction of dissolved organic matter from aqueous extracts of four crop species, hairy vetch (Vicia villosa L.), crimson clover (Trifolium incarnatum L.), red clover (Trijolium pratense L.) and oats (Arena sativa L.) on two soils of different texture and to determine the subsequent effects of sorption on phytotoxicity using a bioassay. Sorption to both a sandy and silty textured soil fit a constant partitioning, isotherm and the affinity constant for sorption were not statistically different between the soils. A bioassay with winter wheat (Triticum aestivum L.) seedlings showed that the hairy vetch, crimson clover and red clover extracts were phytotoxic. Reaction with soil for 24 h resulted in the elimination of phytotoxicity of these three crop extracts at the 5% significance level. The sorption of allopathic compounds released from crop residues may limit the expression of allelopathy in the field. However, the initial phytotoxicity after soil incorporation may coincide with the early, critical stage of weed emergence and establishment, indicating that allelopathy may still play a role in weed management despite sorption of the allelopathic compounds to soil surfaces.

Author Keywords: allelopathy; bioassay; phenolics; phytotoxicity; plant extracts

KeyWords Plus: AQUATIC HUMIC SUBSTANCES; MUSTARD SEEDLING GROWTH; SPECTROSCOPIC PROPERTIES; MOLECULAR-WEIGHT; PHENOLIC-ACIDS; OXIDATION; ADSORPTION; EXTRACT; CARBON; IRON

Addresses: Ohno T (reprint author), Univ Maine, Dept Plant Soil & Environm Sci, 5722 Deering Hall, Orono, ME 04469 USA
　

Title: Allelochemicals isolated from Canada thistle shoots

Author(s): Burda S, Oleszek W

Source: ALLELOPATHY JOURNAL 14 (1): 23-33 JUL 2004

Abstract: Five fractions obtained by chromatographic separation of methanolic extract from Canada thistle [Cirsium arvense (L.) Scop.] shoots were tested on pepperwort seed germination. Fractions that showed inhibitory activity were further purified to yield six pure compounds. Their chemical structures were elucidated on the basis of their UV, FAB-MS and H-1 NMR spectra and finally were confirmed by HPLC co-chromatography with known samples. All the compounds found were phenylpropenic acids or their tartaric esters and were identified as p-coumaric, caffeic, ferulic, caftaric, chicoric and diferuloyltartaric acids. Allelopathic activity of the extracted compounds was assessed on the basis of reduction in seed germination and inhibition of shoot and radicle elongation of wheat, rye, barley, oat, lettuce, and pepperwort. At the concentration of 10(-1) M, all compounds were practically inactive, while at 10(-3) M, the most active were caftaric acid and chicoric acid. Both these acids significantly inhibit shoot and root elongation of lettuce, pepperwort and the cereals excluding wheat. At 10(-3) M the most of the compounds tested strongly inhibit seed germination. In the cereal crops, barley was most sensitive to phenylpropenic acids from Canada thistle shoots.

KeyWords Plus: ACID; RHIZOSPHERE; CUCUMBER

Addresses: Burda S (reprint author), Inst Soil Sci & Plant Cultivat, Dept Biochem, Czartoryskich 8, Pulawy, PL-24100 Poland
E-mail Addresses: burda@iung.pulawy.pl, wo@iung.pulawy.pl

Title: Allelopathic effects of water-soluble leaf epicuticular material from Dittrichia viscosa on seed germination of crops and weeds

Author(s): Stavrianakou S, Liakoura V, Levizou E, Karageorgou P, Delis C, Liakopoulos G, Karabourniotis G, Manetas G, Manetas Y

Source: ALLELOPATHY JOURNAL 14 (1): 35-41 JUL 2004

Abstract: The effects of Diurichia viscosa epicuticular. water soluble allelochemicals on seed germination and early radicle growth were studied on 16 plant species 1(a) crops: Helianthus annuus, Hordeum vulgare, Lens culinaris, Lycopersicum esculentum, Phaseolus vulgaris. Zen mays. (b) weeds: Amarmuhus retroferus, Avena sterilis, Chenopodium album. Papaver rhoeas, Portulaca oberacea and (c) ruderal/wild species: Hirsfeldia incana, Micromeria graeca, Nigela damascena, Psoralen bituminosa. Sanguisorba minor]. growing in same habitat with donor plants. The allelochemicals, inhibited the germination rate. final germination (%) and radide growth in 14 plant spp. except Phaseolus vnlgaris and Psoralea bituminosa. The weeds were very sensitive but some cultivated species were more resistant. these species-specific differences could be attributed to target recipient seed size. small seeds being more sensitive. The use of D. viscosa allelochemicals as selective herbicides for weed management may be promising.

Author Keywords: allelopathy; crops; Dittrichia viscosa; germination speed; radicle growth; weeds

KeyWords Plus: INULA-VISCOSA

Addresses: Manetas Y (reprint author), Agr Univ Athens, Dept Agr Biotechnol, Lab Plant Physiol, Iera Odos 75, Athens, GR-11855 Greece
E-mail Addresses: Y.Manetas@upatras.gr

Title: Inhibitory effects of tamarind (Tamarindus indica L.) on polypathogenic fungi

Author(s): John J, Joy M, Abhilash EK

Source: ALLELOPATHY JOURNAL 14 (1): 43-49 JUL 2004

Abstract: A preliminary study evaluated the influence of tamarind leaf extract [5, 10, 15, 25 and 50 % (w/v)] on the growth of certain polypathogenic fungi (Phytophthora, Colletotrichum gloeosporioides, Alternaria solani, Fusarium solani, Rhizoctonia bataticola, Sclerotium rolfsii, Pellicularia filamentosa and Macrophomina phaseolina), which cause widespread crop damage in the home gardens of Kerala. Tamarind leaf extract suppressed the growth of all the fungi spp. at 3 days after inoculation and caused maximum suppression in Phytophthora palmivora (up to 81 %) and Rhizoctonia bataticola (up to 87 %) - the major pathogens of many crops in homesteads. The tamarind leaf extract offers great opportunity for use as an antifungal botanical to control seed, soil and air borne phytopathogenic fungi.

Author Keywords: Alternaria solani; antifungal; botanical; Colletotrichum glocosporioides; Fusarium solani; Macrophomina phaseolina; Pellicularia filamentosa; Phytophthora palmiovora; polypathogenic fungi; Rhizoctonia balaticola; Sclerotium rolfsii; Tamarindus indica; tamarind leaf

KeyWords Plus: PLANTS

Addresses: John J (reprint author), Kerala Agr Univ, Coll Agr, Kasaragod, Kerala 671328 India
E-mail Addresses: jjkau@rediffmail.com

Title: Allelopathic evaluation of selected cover crops for weed control in the humid tropics

Author(s): Casini P

Source: ALLELOPATHY JOURNAL 14 (1): 51-58 JUL 2004

Author Keywords: Ageratum conyzoides; chick weed; cogongrass; cover crops; Imperata brasiliensis; wed control

Addresses: Casini P (reprint author), Univ Florence, Dipartimento Sci Agron & Gest Territorio Agrofore, Ple Cascine 18, Florence, I-50144 Italy
E-mail Addresses: paolo.casihia@unifi.it

Title: Activity of water extracts of Cistus ladanifer and Lavandula stoechas in soil on germination and early growth of wheat and Phalaris minor

Author(s): Dias AS, Dias LS, Pereira IP

Source: ALLELOPATHY JOURNAL 14 (1): 59-64 JUL 2004

Author Keywords: Allelopathy; Cisrus ladanifer; early growth; germination; Lavandula stoechas; Phalaris minor; soil; weed control; wheat

KeyWords Plus: CUCUMBER; ALLELOPATHY; PRODUCTS

Addresses: Dias LS (reprint author), Univ Evora, Ctr Ecol & Environm, Chem Ecol Unit, Ap 94, Evora, P-7002554 Portugal
E-mail Addresses: lsdias@uevora.pt

Title: Allelopathic effects of weed leaf leachates on seed germination of blackgram (Phaseolus mungo L.)

Author(s): Dongre PN, Singh AK, Chaube KS

Source: ALLELOPATHY JOURNAL 14 (1): 65-70 JUL 2004

Author Keywords: Ageratum conyzoides; Anagallis arvensis allelopathy; Eclipta alba; germination; Lippia nodifora; Parthenium hysterophorus; Phaseolus mungo; Phyllanthus niruri; Pluchea lanceolata; Polygonum plebejum

Addresses: Dongre PN (reprint author), KN Govt Postgrad Coll Gyanpur Bhadohi, Dept Biol, Varanasi, Uttar Pradesh 221304 India
　

Title: Effect of Ageratum conyzoides extracts on the larvae of Metanastria lattipennis

Author(s): Marngar D, Kharbuli B

Source: ALLELOPATHY JOURNAL 14 (1): 71-75 JUL 2004

Author Keywords: Ageratum conyzoides; Metanastria lanipennis; caterpillars; pine needles; methanol extract; malformation

KeyWords Plus: DIVERSITY

Addresses: Kharbuli B (reprint author), NE Hill Univ, Dept Zool, Shillong, Meghalaya 793022 India
E-mail Addresses: bkharbuli@hotmail.com

Title: Pioneers of allelopathy: XIV. Eiji Tsuzuki

Author(s): Xuan TD

Source: ALLELOPATHY JOURNAL 13 (2): 129-136 APR 2004

Abstract: Professor Eiji Tsuzuki is a leading agronomist in Japan. Allelopathy research had been his major activity, besides rice improvement (analysis of characteristics in aromatic rice, breeding its variety and application of pyroligneous acid with charcoal mixture to stimulate rice growth). He exploited allelopathic properties of the plants for biological weed control, to reduce dependence on present herbicides and pesticides in agriculture. He has (a) elucidated the allelopathic characteristics of many crop plants by identifying allelochemicals, (b) studied their effects on other plants, weeds and plant pathogens, (c) their response to soil incorporated, allelopathic materials and (d) found appropriate methods, time of application-and dose of allelopathic materials for greater benefits to rice farmers.

Addresses: Xuan TD (reprint author), Miyazaki Univ, Fac Agr, Lab Crop Sci, Miyazaki, 8892192 Japan
E-mail Addresses: xuan@vysa.jp

Title: Allelopathic plants: Buckwheat (Fagopyrum spp.)

Author(s): Xuan TD, Tsuzuki E

Source: ALLELOPATHY JOURNAL 13 (2): 137-148 APR 2004

Abstract: Buckwheat is not only an important crop in many countries, but also is utilized for soil improvement and biological control of pests and weeds. Application of its plants biomass or pellets to rice field are not injurious to rice plants. Its biomass at 1-2 t ha(-1), significantly reduces the emergence and growth of major upland weeds (Canada thistle and quackgrass) and paddy weeds (barnyardgrass and monochoria). Early incorporation of buckwheat plants biomass or pellets in soil, provides greater weed control. The allelopathic Potential of buckwheat species, followed the order: perennial > tartary > annual. Its stem is more allelopathic than leaves. Many allelochemicals (alkaloids, phenolics, long-chain fatty acids, flavonoids) have been isolated from its shoots, roots and seeds and these are responsible for allelopathic activities. The exploitation of allelopathic properties of buckwheat may help to reduce the use of synthetic agrochemicals.

Author Keywords: allelochemicals; allelopathy research; buckwheat; Fagopyrum spp.; pellets; rice; weed

KeyWords Plus: WEED MANAGEMENT; INHIBITORS; SEEDS

Addresses: Tsuzuki E (reprint author), Miyazaki Univ, Fac Agr, Lab Crop Sci, Miyazaki, 8892192 Japan
E-mail Addresses: xuan@vysa.jp

Title: Methods to determine allelopathic potential of crop plants for weed control

Author(s): Xuan TD, Eiji T, Shinkichi T, Khanh TD

Source: ALLELOPATHY JOURNAL 13 (2): 149-164 APR 2004

Abstract: Weed interference is a serious problem in rice crop, hence, the overuse of synthetic herbicides and agrochemicals have caused environment pollution, unsafe agricultural products and human health concerns. Many plants in the ecosystems possess strong allelopathic potential, which can be exploited for biological control of paddy weeds. This review describes major procedures used in laboratory, greenhouse and field studies to successfully apply plant allelopathic properties for eco-friendly rice production. Several higher plants [alfalfa (Medicago saliva L.), buckwheat (Fagopyrum spp.), billy goat weed (Ageratum conyzoides), kava (Piper methysticum L.) and neem (Azadirachta indica)] biomass at 1-2 tons ha(-1) significantly reduced the paddy weeds biomass and increased the rice yield. Moreover, numerous promising growth inhibitors found in the higher plants can be utilized for the development of novel bio-herbicides and pesticides.

Author Keywords: allellochemicals; allelopathy; higher plants; inhibition; paddy weeds; rice

KeyWords Plus: MEDICAGO-SATIVA L.; NATURAL HERBICIDE; ALFALFA; RICE; GROWTH; SOIL; ALLELOCHEMICALS; GERMINATION; SICKNESS; CLOVER

Addresses: Eiji T (reprint author), Miyazaki Univ, Fac Agr, Lab Crop Sci, Miyazaki, 8892192 Japan
E-mail Addresses: xuan@vysa.jp

Title: Allelopathic plants: 11. Cardaria draba (L.) Desv.

Author(s): Qasem JR

Source: ALLELOPATHY JOURNAL 13 (2): 165-172 APR 2004

Abstract: Whitetop (Cardaria draba) is a noxious perennial weed found throughout the world and exhibits a wide range of ecological tolerance. It is very competitive with several crops ranging from field crops to fruit trees, has little economic value and is toxic to cattle. The weed quickly forms pure colonies that are impossible to be invaded by other plant species and surrounded by an inhibitory zone. Although it prefers alkaline conditions, it is highly successful in different soil types. Its ability to reproduce from seeds and vegetatively by creeping roots, make it difficult to control by traditional weed control methods. The large proportion of belowground tissue and the wide variation in phenology among plants at a given. time, causes difficulty in chemical control. This species interferes with other plant species through competition and allelopathy. Shoot and root extracts, plant residues, volatiles and foliage leachates all exhibited phytotoxicity.

Author Keywords: allelopathy; Cardaria draba; whitetop; weed ecology

KeyWords Plus: HOARY CRESS

Addresses: Qasem JR (reprint author), Univ Jordan, Fac Agr, Dept Plant Protect, Amman, Jordan
E-mail Addresses: jrqasem@ju.edu.jo

Title: Allelopathic influences of common cocklebur (Xanthium italicum Moretti) on maize

Author(s): Casini P

Source: ALLELOPATHY JOURNAL 13 (2): 189-199 APR 2004

Abstract: Extracts of residues and root exudates of common cocklebur (Xanthium italicum Moretti) were tested for their allelopathic influence on the seed imbibition, germination and the early development of six maize (Zea mays L.) hybrids. The negative effects of weed residues were notable starting from seed imbibition. Cv. Giorgio proved to be the most sensitive to water extracts of residues. At the 1% level, germination and root number were significantly reduced by 20 and 65%, respectively, compared to control. Strong negative effects on germination, corresponding to -34% and -27%, were recorded with cvs. Giorgio and Funo in the presence of the root exudates. Data on leaf area and plant height confirmed the negative and significant effects of Xanthium residues on maize development, while the effects of root exudates showed only a difference of response between the hybrids. In summary, results reported in this study showed notable allelochemical effects of X italicum residues on maize similar to those observed with relatives. The component "genotype" was particularly evident in the experiment with water extracts of residues and root exudates.

Author Keywords: allelopathy; common cocklebur; germination; maize; residue extracts; root exudates; Xanthium italicum; Zea mays

KeyWords Plus: CORN ZEA-MAYS; GROWTH; WEEDS

Addresses: Casini P (reprint author), Univ Florence, Dipartimento Sci Agron & Gest Terr Agroforestale, Ple Cascine 18, Florence, I-50144 Italy
E-mail Addresses: paolo.casini@unifi.it

Title: Effect of Solanum lycocarpum fruit extract on sesame seed germination and seedling growth

Author(s): Oliveira SCC, Ferreira AG, Borghetti F

Source: ALLELOPATHY JOURNAL 13 (2): 201-209 APR 2004

Abstract: Solanum lycocarpum St.Hil. (wolf fruit) is a rare shrub in native vegetation but is common in disturbed areas of the Cerrado (Brazilian savanna). This species bear fruits throughout the year. The effect of S. lycocarpum fruit pulp extract was tested seed germination and seedling growth of on Sesamum indicum L. (sesame) at three temperatures (22 degreesC, 30 degreesC and 38 degreesC). Pre-germinated seeds of sesame were grown for 5 days in 0, 1, 2, 3, 4, or 5% (w/v) fruit extracts. Polyethylene glycol solutions (PEG 6000) were used as controls. Seed germination was reduced by both the extracts and PEG solutions, except at 30 degreesC. The extracts caused necrosis of the root tip and absence of root hairs and formation of secondary roots. None of these alterations were observed in the PEG controls. Allelochemicals present in the S. lycocarpum fruit are promising as natural herbicides, as these are effective over wide range of temperatures.

Author Keywords: allelopathy; Cerrado; Sesamum indicum; Solantan lycocarpum

Addresses: Ferreira AG (reprint author), Univ Fed Rio Grande Sul, IB, Dept Bot, Post Box 15015, Porto Alegre, RS BR-91501970 Brazil
E-mail Addresses: ferreira@unb.br