Alelopatia de algumas espécies de plantas aquáticas

Abstract

Allelopathy is a natural interference that occurs when plants produce substances that, when released to the environment, can benefit or harm other organisms. This study aimed to evaluate the allelopathic potential of the hydroalcoholic extract from eight aquatic plants species from the western region of Paraná: Azolla caroliniana, Eichornia crassipes, Egeria densa, Ludwigia peploides, Hydrocotyle ranunculoides, Oxycaryum cubens, Pistia stratiotes and Salvinia sprucei. The extracts were evaluated in germination and growth bioassays using lettuce (Lactuca sativa), picão-preto (Bidens pilosa L.), sorghum (Sorghum bicolor) and capim-amargoso (Digitaria insularis) seeds as targets. The extracts were prepared at concentrations of 0.1; 0.2; 0.4; 0.8 (mg/mL) using 2-morpholino-ethanesulfonic acid solution (MES). All tests were performed in quadruplicate. It can be observed that the extracts that showed better growth inhibition in the lettuce bioassay were the (aerial) part of E. crassipes and L. peploides extracts, which presented a higher inhibition than the glyphosate and atrazine controls. In the bioassay with picão-preto seeds, the most expressive result for germination was the extract of L. peploide (root), which presented a superior result than glyphosate. In the dry mass test, the extracts E crassipes (aerial) and P. stratiotes (root) stood out, which showed a reduction in biomass accumulation. In the tests with sorghum, the extracts of E. crassipes (aerial) and (root) proved to be efficient against the growth of the radicles and in the dry biomass test, presenting results superior to atrazine. In tests against capim amargoso, the macrophyte E. crassipes (aerial) and (root) proved to be efficient in the growth of radicles. The extracts of H. ranunculoides (aerial) and (root) showed better results than atrazine in dry biomass. In the determination of total phenols, extracts from aerial and root L. peploide stood out with 78.4 (mg EAT g - ¹) and 75.82 (mg EAT g - ¹), respectively. This result suggests that the allelopathic effect of the plant is correlated with the phenolic content obtained. The results obtained demonstrate the biological potential of macrophytes as bioherbicides.