Abstract
The present study aims to test the Acritopappus confertus (Gardner) R. M. King & H. Rob. essential oil allelopathic potential on the germination and inital development of Cenchrus echinatus L. and Lactuca sativa L. seedlings, in addition to identifying and quantifying chemical constituents. The chemical composition analysis was performed by gas chromatography (GC-FID) and gas chromatography coupled to mass-spectrometry (GC-MS). For the allelopathic assays, the essential oil was emulsified with dimethylsulfoxide (DMSO) in a 1:1 ratio, and diluted in distilled water to obtain 0.001, 0.01, 0.10, 0.25, 0.50, 0.75 and 1% c. The control consisted of 1% aqueous DMSO solution.Treatments were performed in five repetition with 20 seeds each. The pH of the oils were measured and adjusted to a scale of 6 to 7. Assays were conducted in a germination chamber at 25 °C with a 12h photoperiod. Seed germination, Germination Speed Index (GSI), caulicle and radicle length were analyzed. The data were subjected to analysis of variance and the means were compared by Tukey test (p<0.05), through the ASSISTAT. The constituents mycene, β-pinene and limonene stood out the most in chemical analysis. The essential oil did not influence C. echinatus and L. sativa seed germination, however it influenced GSI and seedling development. The effects observed herein may be due to chemical constituents found in the studied species, which may act in an isolated or combined manner.
Highlights
Allelopathy can be defined as an important mechanism in which living or dead plants release chemical compounds which can interfere in a negative or positive way with the growth and development of other plants
The chemical composition analysis was performed by gas chromatography (GC-FID) and gas chromatography coupled to mass-spectrometry (GC-MS)
Gas chromatography coupled to mass spectrometry (GC-MS) analysis were performed on an Agilent Technologies AutoSystem XL GC-MS system operating in EI mode at 70 eV, equipped with a split/splitless injector (250°C)
Summary
Allelopathy can be defined as an important mechanism in which living or dead plants release chemical compounds which can interfere in a negative or positive way with the growth and development of other plants. Allelopathy plays an important role in dominance, plant succession and plant community formation, being an important colonization strategy of many exotic species in natural communities (Li et al, 2011; Oliveira, Gualtieri, Domínguez, Molinillo & Montoya, 2012) Many secondary metabolites, such as phenolic acids, flavonoids, tannins and others, possess allelopathic activity. Through allelopathic potential and constituent analysis, new alternatives for spontaneous and cultivated plant management may be observed, in addition to allowing diversification in agricultural crops (Silva et al, 2011; Gusman, Vieira & Vestena, 2012) Within this context, several pieces of research have proven the allelopathic action in species of botanical substances, such as Poaceae, Euphorbiaceae, Lamiaceae, Asteraceae, among others. The present study aims to test the A. confertus essential oil allelopathic potential on the germination and development of Cenchrus echinatus L. and Lactuca sativa L. seedlings, in addition to identifying and quantifying chemical constituents
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