Evidence of phytotoxicity in a fast-growing shrub useful for savanna restoration in Central Brazil

Finding fast-growing native species able to interfere in invasive grass species’ growth is essential to restore savannas and grasslands, where native tree growth is rather limited. We tested the phytotoxicity of Lepidaploa aurea (Mart. ex DC.) H.Rob. (Asteraceae), a native shrub from the Brazilian savanna that apparently inhibits the growth of invasive grasses in degraded areas and in areas under restoration process. We performed experiments in Petri dishes and soil conditions using four receiver species: three eudicots: Lactuca sativa L., Raphanus sativus L., Solanum lycopersicum L. and a monocot: Sorghum bicolor L. Moench. These are model species commonly used in phytotoxic studies for their known germination rates and high sensitivity to allelochemicals. We tested the effects of aqueous extracts of L. aurea’s leaves and roots, in four concentrations (10, 5, 2.5, 1.25%) and a control (distilled water). We performed tests in natural versus sterilized soils to identify the influence of soil microbiota in L. aurea’s phytotoxicity. We found phytotoxic effects in all tested conditions. Leaf extracts had more accentuated negative effects on target plants than did root extracts. The growth of receiver plants’ root was more affected than shoot growth. Lepidaploa aurea can be an important ally for the restoration of degraded areas savannas and grasslands. Studies considering species that co-occur with L. aurea in conserved and disturbed are as are necessary to confirm this allelopathic potential.