This 15-days study evaluated the effects of drought stress (40 % field capacity) at the initial reproductive stage and increase of the allelopathic potential of Cosmos sulphureus Cav. Thereafter, fresh leaves were collected for malondialdehyde and proteomic tests and to prepare crude extract. Bioassays were done on crops Lactuca sativa L., Sorghum bicolor (L.) Moench, Cucumis sativus L.] and weeds Urochloa decumbens (Stapf) Webster, Portulaca oleracea L. and Panicum maximum Jacq.. All extracts significantly inhibited the germination (5-90 %), depending on the species and extract concentration. However, the extracts from stressed plants were more inhibitory to germination (22.74 %), shoot growth (43.91 %) and root growth (35.60 %) than extracts from non-stressed plants (15.69 %, 44.70 % and 33.65 %, respectively). No significant differences were observed between the drought and non-stress conditions. It was concluded that drought stress (40 % field capacity) for 15-days, at the initial reproductive stage in Cosmos sulphureus Cav. plants, did not increase the allelopathic potential of this specie. These findings support further study of its bioherbicidal activity and sustainable weed control.
Novello et al. (Thu,) studied this question.