Allelopathy has been largely studied for several Com- positae species, and a significant amount of information is available in particular on Helianthus annuus L.. Only a few studies, however, have considered the related perennial species H. tuberosus L. which is cultivated in Europe as vegetable and for industrial uses, and behaving as a weed in summer annual crops. The objectives of this study were to assess the allelopathic effects of different populations of H. tuberosus on germination and seedling growth of some cultivated and weed species and to identify the allelochem- icals responsible for the inhibitory activity. The release of the allelopathic compounds during the natural degrada- tion of residues was simulated with a bioassay using Parker plates, filled with 150 g of soil and sand mixture, and different amounts of H. tuberosus dry leaf tissue (0.5, 1 and 1.5 g per plate). H. tuberosus rough material came from 4 cultivars (Fuseau, Red Fuseau, Stampede, Hybrid Stampede) and a weedy biotype (Italian). Inhibition of dry tissue was assessed in terms of seed germination, and shoot and root elongation of Digitaria sanguinalis, Echinochloa crus-galli, Lactuca sativa, and Lycopersicon esculentum. Fuseau resulted the most toxic cultivar on germination and growth of D. sanguinalis, showing an important inhibitory effect already at the lowest rate (0.5 g). None of the cultivars tested significantly inhibited the germination of E. crus-galli, even though root elongation was strongly affected at 1.5 g by almost all cultivars. Both shoot and root length of L. sativa was strongly affected by all cultivars. Root growth, in particular, was reduced for more than 78% at 1.5 g. On average, L. esculentum resulted the most sensitive indicator species, as no germination was observed, starting from the smallest amount of residues. Among the tested populations, the strongest inhibition activity, was recorded in the cultivars Fuseau and Stampede and in the biotype Italian. Powdered leaf tissues of these populations were used for the solvent extraction, with either hexane, ethyl ether, or ethyl acetate. Toxicity of the extracts on germination and shoot and root elongation of L. sativa was assessed in Petri dishes (5 cm). Ethyl ether fraction from the cultivar Fuseau was, on average, the most toxic. About 90% of shoot length reduction was achievable with only 0.21 lg/ dish of extract. This fraction was analyzed with liquid- mass chromatography by detecting phenolic compounds. Salicylic acid was detected in all fractions tested at an average concentration of 10.16 mg/kg. Few amounts of o coumarinic and p coumarinic acids were also found. The phenols detected in this study are often associated with allelopathic behavior in Compositae weed species. Alle- lopathy may be advantageous to H. tuberosus cultivation, as it potentially reduces the sensitivity of this species to weed, theoretically allowing a reduction of inputs required for weed control, even in the successive crop, due to the release of phenolic compounds. On the other hand, allelopathic activity of H. tuberosus residues may be unfavorable to the sensitive crops cultivated after H. tuberosus or planted in an area infested by this species

Identification of allelopathic compounds from Helianthus tuberosus L. leaves

TESIO, FRANCO;VIDOTTO, Francesco;FERRERO, Aldo
2008-01-01

Abstract

Allelopathy has been largely studied for several Com- positae species, and a significant amount of information is available in particular on Helianthus annuus L.. Only a few studies, however, have considered the related perennial species H. tuberosus L. which is cultivated in Europe as vegetable and for industrial uses, and behaving as a weed in summer annual crops. The objectives of this study were to assess the allelopathic effects of different populations of H. tuberosus on germination and seedling growth of some cultivated and weed species and to identify the allelochem- icals responsible for the inhibitory activity. The release of the allelopathic compounds during the natural degrada- tion of residues was simulated with a bioassay using Parker plates, filled with 150 g of soil and sand mixture, and different amounts of H. tuberosus dry leaf tissue (0.5, 1 and 1.5 g per plate). H. tuberosus rough material came from 4 cultivars (Fuseau, Red Fuseau, Stampede, Hybrid Stampede) and a weedy biotype (Italian). Inhibition of dry tissue was assessed in terms of seed germination, and shoot and root elongation of Digitaria sanguinalis, Echinochloa crus-galli, Lactuca sativa, and Lycopersicon esculentum. Fuseau resulted the most toxic cultivar on germination and growth of D. sanguinalis, showing an important inhibitory effect already at the lowest rate (0.5 g). None of the cultivars tested significantly inhibited the germination of E. crus-galli, even though root elongation was strongly affected at 1.5 g by almost all cultivars. Both shoot and root length of L. sativa was strongly affected by all cultivars. Root growth, in particular, was reduced for more than 78% at 1.5 g. On average, L. esculentum resulted the most sensitive indicator species, as no germination was observed, starting from the smallest amount of residues. Among the tested populations, the strongest inhibition activity, was recorded in the cultivars Fuseau and Stampede and in the biotype Italian. Powdered leaf tissues of these populations were used for the solvent extraction, with either hexane, ethyl ether, or ethyl acetate. Toxicity of the extracts on germination and shoot and root elongation of L. sativa was assessed in Petri dishes (5 cm). Ethyl ether fraction from the cultivar Fuseau was, on average, the most toxic. About 90% of shoot length reduction was achievable with only 0.21 lg/ dish of extract. This fraction was analyzed with liquid- mass chromatography by detecting phenolic compounds. Salicylic acid was detected in all fractions tested at an average concentration of 10.16 mg/kg. Few amounts of o coumarinic and p coumarinic acids were also found. The phenols detected in this study are often associated with allelopathic behavior in Compositae weed species. Alle- lopathy may be advantageous to H. tuberosus cultivation, as it potentially reduces the sensitivity of this species to weed, theoretically allowing a reduction of inputs required for weed control, even in the successive crop, due to the release of phenolic compounds. On the other hand, allelopathic activity of H. tuberosus residues may be unfavorable to the sensitive crops cultivated after H. tuberosus or planted in an area infested by this species
2008
5th International Weed Science Congress
Vancouver, Canada
23-27/06/2008
Proceedings 5th International Weed Science Congress
International Weed Science Society (IWSS)
156
157
http://www.iwss.info
allelopathy; Jerusalem artichoke; seed germination
F. Tesio; L. Weston; F. Vidotto; A. Ferrero
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/67628
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