The increased focus on sustainable agriculture and the appreciation of consumers for products with a reduced environmental impact, has resulted in a growing interest for phytochemicals capable to manage weeds and plant microbial diseases, both at agronomic and horticultural level. Many efforts have been made to identify the phytotoxic effect of essential oils and of their single constituents, but the results are scattered in a myriad of papers, making difficult to draw sound conclusions and reducing the possibility to infer which chemotype or which cultivar of an essential oil bearing plant is better suited to provide the best phytotoxic potential. For such reasons here at LS9 we have performed an in vitro screening on the phytotoxic effect at pre and post-emergence growth of twenty-five essential oils on plantlets of a standard target species (Solanum lycopersicum) representing the Solanaceae family, whose weed members constitute a potential danger in organic agriculture.
Results showed that rose-scented Pelargonium capitatum and Aniba rosaeodora essential oils are potential natural herbicides endowed with very strong activities against Solanum lycopersicum both in pre and post-emergence stages, with potency greater or comparable to those of other renewed phytotoxic essential oils already used in commercial natural herbicides. According to a predictive model built with the help of multivariate data analysis, an higher content in monoterpene alcohols, aldehydes or phenylpropanoids can be used as a predictor of phytotoxic activity in essential oils. In particular, while monoterpene alcohols are active on both seeds and plantets, aldehydes exert their activity mostly on germinated plantlets. Rather than randomly bioassaying essential oils, these structural and activity clues can be used to maximize chances of finding phytotoxic compounds.
Full details are available in the latest number of Industrial Crops and Products.
Rolli E, Marieschi M, Maietti R, Sacchetti G & Bruni R (2014) Comparative phytotoxicity of 25 essential oils on pre- and post-emergence development of Solanum lycopersicum L.: a multivariate approach. Industrial Crops and Products 60, 280-290.