Allelopathy of ripe fruits of ilex paraguariensis ("mate") on corn cultivation

Abstract

This work was carried out to study the allelopathic effect of ripe fruits of mate (Ilex paraguariensis St. Hil.) on the germination and growth of hybrid corn SAVE 484 (Zea mays L.) and, in addition, to determine if the time of permanence of the fruits on the soil affected the allelopathic effect on corn. Ripe fruits of Ilex paraguariensis ("mate") were added to plastic vases with soil adjusted to corn cultivation. Seeds of maize were sowed right away to the incorporation of the fruits either 30 or 60 days after. Experiments were also performed in laboratory with extracts of "mate" fruits and PEG 6000, osmotic substances in concentration similar to those from the extracts, in order to distinguish the osmotic from allelopathic effect. In soil, as well as in laboratory using paper as substrate, the germination and the emergence of the corn were not affected, but the growth and the development were. Plant height, length of the first node, length of the leaves, dry matter of shoot and root, number of adventitious roots, length of the tap root were affected either by the presence of fruits or by their extracts showing an inhibition of development, possibly caused by the allelochemicals present. The number of root hairs in corn seedlings showed to be a very sensible measurement to allelopathic substances, which rested in soil for 60 days, at least, after the addition of the fruits of "mate".