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Ethanol extracts obtained from aerial parts of 71 native plants from Central Argentina were tested for their herbicidal activity in germination assays on Avena sativa and Raphanus sativus . Extracts derived from Angelphytum aspilioides , Baccharis salicifolia , Cortaderia rudiuscula , Eupatorium hookerianum and Mandevilla laxa , showed 100% inhibition of the germination of A. sativa at 10 mg/ml. In the case of R. sativus , extracts from Achyrocline tomentosa , Angelphytum aspilioides , B. salicifolia , Melissa officinalis , Minthostachys verticillata , Ophryosporus charua and Podranea ricasoliana , applied at 10 mg/ml, showed 100% germination inhibition. For each extract, the mean effective concentrations that inhibit germination (ECg 50 ), root (ECr 50 ) and shoot (ECs 50 ) growth were determined. According to these values and the extract yield, an index was calculated in order to establish a ranking of the most active plants. For inhibition of A. sativa , the ranking was B. salicifolia > A. aspilioides > C. rudiuscula > M. laxa > E. hookerianum . The ECg 50 , ECr 50 and ECs 50 of B. salicifolia against A. sativa were 0.36, 0.88 and 0.91 mg/ml, respectively, showing more activity than that of 2,4-D as a germination inhibitor and 44 and 1.1 times less active than 2,4-D as a root and shoot inhibitor, respectively. The ranking for the inhibition of R. sativus was O. charua > A. aspilioides > P. ricasoliana > B. salicifolia > A. tomentosa > M. officinalis > M. verticillata . The O. charua extract presented ECg 50 , ECr 50 and ECs 50 of 1.04, 1.04 and 1.49 mg/ml, respectively. According to the obtained results, the extracts of B. salicifolia and of A. aspilioides were the only ones capable of inhibiting the germination and growth of both test species. |
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