Efeito do extrato seco de Conyza bonariensis (L.) Cronquist no desenvolvimento inicial de Amaranthus hybridus L.

Abstract

Allelopathy plays a fundamental role in the formation of plant communities, influencing germination processes, growth, and competition among species. Allelopathic bioassays allow the identification of bioactive compounds capable of altering the development of other plants, contributing to a deeper understanding of chemical interactions within the environment. In this study, we aimed to evaluate the allelopathic effects of dry extract from Conyza bonariensis (L.) Cronquist (hairy fleabane) on the initial development of another pioneer species, Amaranthus hybridus L. (smooth pigweed). For the assay, A. hybridus seeds were sown in pots containing commercial substrate and then subjected to treatments with 5% and 10% dry matter derived from leaves and radicles of C. bonariensis. Seedling emergence parameters were monitored daily up to 20 DAP, and at 40 DAP, the dry mass of the shoots and roots of A. hybridus was quantified. A reduction in germination-related parameters was observed, while dry matter accumulation increased in the evaluated species. No dose–response effect was detected for any of the analyzed variables.