Comparative phytotoxicity of 25 essential oils on pre- and post-emergence development of Solanum lycopersicum L.: a multivariate approach

Twenty-five essential oils extracted from different sources (Aniba rosaeodora wood, Cananga odorata flowers, Cannabis sativa inflorescences, Cymbopogon citratus leaves, Citrus limon leaves, Citrus nobilis leaves, Cupressus sempervirens leaves, Curcuma longa rhizomes, Hypericum perforatum leaves, Illicium verum fruits, Melaleuca alternifolia leaves, Mentha×. piperita leaves, Mentha spicata leaves, Monarda fistulosa leaves, Ocimum micranthum leaves, Ocimum basilicum leaves, Ocotea quixos leaves, Pelargonium capitatum leaves (two samples), Pinus nigra leaves, Pogostemon cablin leaves, Syzygium aromaticum leaves, Thymus vulgaris leaves, Vetiveria zizanoides roots, Zingiber officinale rhizomes) were screened for their phytotoxic behavior against Solanum lycopersicum seeds and seedlings in order to assess their capacity to inhibit germination, damage germinated seeds and alter the normal development of plantlets. The oils were analyzed by means of GC and GC-MS and a relationship between some functional groups and the ability to affect the germination or the development of roots and hypocotiles was evidenced by means of multivariate data analysis. A. rosaeodora, C. citratus, I. verum, M.×. piperita, M. fistulosa, O. micranthum, S. aromaticum and in particular both Pelargonium samples were the most effective in both pre- and post-emergence stages. Multivariate data analysis allowed the construction of a model according to which the higher content in monoterpene alcohols, aldehydes or phenylpropanoids can be used as a predictor of distinct phytotoxic activities.