Response Pattern of Mimosa pudica e Senna obtusifolia to Potentially Allelopathic Activity of Poaceae Species

Allelopathy is an important device to measure interferences affecting the dynamics of plant species in agricultural systems. This study aimed to determine the existence of response patterns of the weeds Mimosa pudica and Senna obtusifolia to species of the family Poaceae, through interaction between species and fractions, and arrangement of the effects. Bioassays of seed germination and radicle and hypocotyl elongation were developed under controlled conditions. Hydro-alcoholic extracts at 1.0% of the leaf, root and seed fractions of four species of Poaceae were tested. Differences in intensity of the effects for species and fractions were verified. The activity pattern observed for Paspalum maritimum was the presence of more intense inhibitions. Among Brachiaria species, the most intense inhibitions were produced by B. brizantha. There was an intense effective response for specificity between species and fractions for germination and radicle elongation, especially for Mimosa pudica. Only the P. maritimum extracts showed specificity and were effective in relation to seed germination and radicle elongation of the species Senna obtusifolia. Lleaf fraction was more effective for inhibition, especially for the species P. maritimum. Comparatively, the species Mimosa pudica was more responsive to the effects of the extracts, especially in relation to radicle and hypocotyl development. The intensity of the allelopathic activities varied as follows: radicle elongation > seed germination > hypocotyl elongation. The arrangement of the results for indicators of inhibition showed a pattern discrimination for the receiving species, suggesting specificity of the extracts.