Allelopathy as a Strategy for Biological Invasion: Calotropis procera and Its Impact on Plant Succession

This article reports on the allelopathic potential of Calotropis procera (Aiton) W.T. Aiton foliage on Handroanthus impetiginosus (Mart. ex DC.) Mattos. Predominant species in semiarid environments, especially in the Caatinga of the Northeast, where it acts as an invasive species. The leaves of C. procera were mixed with soil from the Caatinga and left to decompose for 90 days. The control group consisted only of soil from the Caatinga, Northeast, Brazil. The germination test was conducted in quadruplicate (30 seeds/treatment). For growth, 30 replicates per treatment were used, each with one seedling of the recipient species. The identification of the chemical constituents of C. procera was assessed by GC-MS. The data was submitted to the one-way ANOVA test. Residues from the decomposition of C. procera litter negatively affected seedling germination, with a reduction of up to 80% in the treatments evaluated. The phytochemical analysis showed the presence of 18 compounds, grouped into six main classes. Among the main compounds identified were: α-amyrin (C₃₀H₅₀O) with 2.69% and O-acetyl-β-amyrin (C₃₂H₅₂O₂) with 6.19% concentration. Significant variation was observed in the thickness of the tissues and regions of the radicle, hypocotyl and leaves of H. impetiginosus. C. procera litter has a negative allelopathic potential on the recipient species, which could lead to their reduction in the natural environment.