Allelopathic Activity of Cactus Used in the Foraging in the Brazilian Semi-arid

The use of cactus for forage may cause soil contamination by allelochemicals in order to compromise the future planting or even reforestation of that site. The objective of this work was to evaluate the allelopathic action of cladodes and roots of Cereus jamacaru, Pilosocereus gounellei and Tacinga inamoena on the germination and development of Cenchrus echinatus and Calotropis procera in order to suggest actions that increase efficiency in restoration strategies. Of the species of Cactaceae mentioned above, cladodes and roots were collected for the preparation of the extracts in which two types of extracts were prepared for each organ, one treatment by hot infusion and one cold treatment. Germination Percentages (GP) and Germination Speed Index (GSI) were analyzed. In order to analyze if the extracts presented some allelopathic activity regarding the development of the seedlings, the lengths of the stem and the radicle of the recipient species were measured. The results of this research show that cacti don’t significantly affect GP from seeds of other plants. However, for GSI, roots and cladodes of T. inamoena presented negative allelopathic activity for C. echinatus and C. procera, respectively. In addition to GSI, T. inamoena negatively affected the development of C. echinatus rootlets. In this way T. inamoena is a forage cactus that affects the development of the initial structures of surrounding plants. Thus, the exacerbation of this forage species in natural areas should be avoided, since the released allelochemicals can interfere with the ecological succession of the plant species of that environment.