Resumo

TEJEDA-SARTORIUS, Olga  e  RODRIGUEZ-GONZALEZ, María T.. Weed and vegetable germination and growth inhibitors in amaranth (Amaranthus hypochondriacus L.) residues. Agrociencia [online]. 2008, vol.42, n.4, pp.415-423. ISSN 2521-9766.

Plant residues can have an allelopathic effect on certain weed species, a phenomenon that can be used for their control, but they can also affect crop germination, growth and yield. The objectives of this study were: 1) to evaluate the effect of amaranth (Amaranthus hypochondriacus L.) residue aqueous extract on germination and growth of Echinochloa crus-galli (L.) Beauv., radish (Raphanus sativus L. var. Champion) onion (Allium cepa L.) and carrot (Daucus carota L. var. Nantes); 2) analyze the inhibitory potential of organic extracts from A. hypochondriacus amaranth residues on germination and growth of A. hybridus L. and E. crus-galli. Two biological tests were conducted. For the first, aqueous extracts were prepared in a ratio of 1:2.5 (v/v) amaranth residue:water. The treatments were different concentrations of total phenols phenolic of the extracts. For the second bioassay, organic extracts were prepared in Soxhlet equipment using solvents of increasing polarity (hexane, dichloromethane, and methanol). The extract derived from each solvent was one test treatment. The highest concentrations of total phenolics (108 and 54 ppm) inhibited germination of E. crus-galli and radish (57 and 56%), and radicle (51 to 76%) and shoot (47 to 86%) growth of the species tested. The organic extracts delayed germination. The dichloromethane fraction inhibited A. hybridus radicle (34%) and shoot (66%) growth. The three organic fractions inhibited E. crus-galli radicle growth (25% on average), while the methanol fraction decreased shoot growth (31%). It is concluded that dry amaranth residues possess substances that inhibit germination or growth of Echinochloa crus-galli, radish, onion and carrot. The aqueous and organic extracts affect the analyzed species differentially.

Palavras-chave : Amaranthus hypochondriacus L.; Amaranthus hybridus L.; Echinochloa crus-galli (L.) Beauv.; allelopathy.