Phytotoxic effects of extract and essential oil of Eucalyptus saligna (Myrtaceae) leaf litter on grassland species

Abstract

Under Eucalyptus plantations in the South Brazilian grassland region, few plants establish, and allelopathy may be involved in shaping this pattern. We aimed to assess the phytotoxicity of essential oil and aqueous extract of Eucalyptus saligna Sm. leaf litter on grassland species. We tested the effects of E. saligna pure oil and extract on germination, seedling growth, H2O2 levels and electrolyte leakage of seedling membranes of Paspalum notatum Flüggé, Eragrostis plana Ness (Poaceae), Trifolium repens L. and Lotus corniculatus L. (Fabaceae). Essential oil and aqueous extract of E. saligna affected all recipient species, even at the lowest amounts/concentrations, inhibiting germination and initial growth, and also increasing H2O2 levels and electrolyte leakage of seedling membranes. Essential oil consisted mainly of monoterpenes and presented α-pinene and 1,8-cineole as the major compounds. The extract contained phenolics, and lower levels of these compounds in the extract were associated with decreased phytotoxicity. We conclude that E. saligna contains phytotoxic compounds in leaf litter that generate oxidative stress and lead to membrane damage, affecting seeds and seedling growth. In addition, we relate E. saligna phytotoxicity to monoterpenes that may be released from leaf litter by volatilisation, and phenolics that may be leached by rainfall. Our study indicates that E. saligna has allelopathic potential on the tested grassland species.

Herbicidal potential of lavender (Lavandula angustifolia Mill.) essential oil components on bristly foxtail (Setaria verticillata (L.) P. Beauv.): Comparison with carvacrol, carvone, thymol and eugenol

“…The essential oil of Sydney blue gum (Eucalyptus saligna Sm.) contained phytotoxic compounds (monoterpenes, mainly α-pinene and 1,8-cineole), induced oxidative stress and caused damage to cell membranes, resulting in inhibition of seed germination and growth of the seedling [14]. Red thyme (Thymus vulgaris L.), clove and cinnamon (Cinnamomum zeylanicum Blume) essential oils caused electrolyte leakage on dandelion (Taraxacum officinale F.H.…”

Bioherbicide Potential of Eucalyptus saligna Leaf Litter Essential Oil

“…[18,19] Moreover, in a previous study of our research group, volatiles directly emitted from E. saligna leaf litter essential oil affected germination and seedling growth, generated oxidative stress, and led to damages on seedling membranes of recipient species. [20] However, the potential applicability of essential oils as herbicides depends on the presence of phytotoxic effects when these substances are diluted in water. Essential oil components present variable solubility in water and may be phytotoxic in concentrations even below their aqueous solubility.…”

A strategy of rapidly screening out herbicidal chemicals from Eucalyptus essential oils

“…Eucalyptus species, especially their essential oil fraction, possess biological activities, including antioxidant, antimicrobial and insecticidal activities. In recent years, the herbicidal activity of Eucalyptus essential oils has been widely studied . Previous studies on the herbicidal activity of the essential oils are often limited to one or a few Eucalyptus species and conducted through bioassays to determine their herbicidal activity of the essential oils on weeds without figuring out the herbicidal activities of individual chemical compounds .…”

“…In recent years, the herbicidal activity of Eucalyptus essential oils has been widely studied. [9][10][11] Previous studies on the herbicidal activity of the essential oils are often limited to one or a few Eucalyptus species [12][13][14][15] and conducted through bioassays to determine their herbicidal activity of the essential oils on weeds without figuring out the herbicidal activities of individual chemical compounds. 16 In general, figuring out the herbicidal compounds from plant extracts requires isolation of the individual compounds from the extracts.…”