Herbicidal Activity of Thymbra capitata (L.) Cav. Essential Oil.

Mercedes Verdeguer,Santo Agnello,Pablo Chinchilla,Natalia Torres-Pagan,Marta Muñoz,María Amparo Blázquez,Luz Cabeiras-Freijanes,Mónica Berbegal,Susana García-Plasencia,Alessandra Carrubba,Adele Salamone,Adela M Sánchez-Moreiras,Amira Jouini,Lois Regueira-Marcos

doi:10.3390/molecules25122832

Abstract

The bioherbicidal potential of Thymbra capitata (L.) Cav. essential oil (EO) and its main compound carvacrol was investigated. In in vitro assays, the EO blocked the germination and seedling growth of Erigeron canadensis L., Sonchus oleraceus (L.) L., and Chenopodium album L. at 0.125 µL/mL, of Setaria verticillata (L.) P.Beauv., Avena fatua L., and Solanum nigrum L. at 0.5 µL/mL, of Amaranthus retroflexus L. at 1 µL/mL and of Portulaca oleracea L., and Echinochloa crus-galli (L.) P.Beauv. at 2 µL/mL. Under greenhouse conditions, T. capitata EO was tested towards the emergent weeds from a soil seedbank in pre and post emergence, showing strong herbicidal potential in both assays at 4 µL/mL. In addition, T. capitata EO, applied by spraying, was tested against P. oleracea, A. fatua and E. crus-galli. The species showed different sensibility to the EO, being E. crus-galli the most resistant. Experiments were performed against A. fatua testing T. capitata EO and carvacrol applied by spraying or by irrigation. It was verified that the EO was more active at the same doses in monocotyledons applied by irrigation and in dicotyledons applied by spraying. Carvacrol effects on Arabidopsis root morphology were also studied.

Highlights

The family Lamiaceae is one of the most widely used source of spices, and includes medicinal plants endowed with strong antimicrobial and antioxidant properties [1,2,3,4]
Composition were studied, allowing to assess that the carvacrol chemotype was only present under the hottest and driest conditions. These results demonstrated that is the biosynthetic pathway of phenolic monoterpenes in T. capitata favoured in high-temperature environments, as reported in other
Our studies demonstrated that T. capitata essential oil (EO), and its main compound carvacrol, in either in vitro and in vivo conditions, exhibited great potential against many noxious Mediterranean weeds of cosmopolite distribution, and could be excellent candidates for bioherbicide formulations, which are a very important tool in the context of integrated weed management (IWM), more respectful towards the environment and the ecosystems

Summary

Introduction

The family Lamiaceae is one of the most widely used source of spices, and includes medicinal plants endowed with strong antimicrobial and antioxidant properties [1,2,3,4]. There is a long history of controversies surrounding this family [6], resulting in a considerable number of recent efforts to re-evaluate existing classification by means of molecular phylogenetic analyses [7,8,9,10,11]. Among the most challenging taxa there is the subtribe Menthinae (Lamiaceae, Nepetoideae, Mentheae), which includes well known aromatic plants as peppermint, oregano, savory and thyme (see [12] for a comprehensive review). This led to an enormous number of names [13] with many synonyms under different generic names and, as a consequence, to a considerable taxonomic confusion. The recent molecular phylogenetic analysis of both nuclear ribosomal and plastid markers [12] revealed that this genus had a distinct lineage, dissociated from both Thymus Linnaeus and Satureja Linnaeus [6]

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Results

Conclusion