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SOUZA FILHO, A.P.S.; ALVES, S.M. and FIGUEIREDO, F.J.C.. Allelopathic effects of calopo according to its age and to seed density of the receiver plant. Planta daninha [online]. 2003, vol.21, n.2, pp. 211-218. ISSN 0100-8358. http://dx.doi.org/10.1590/S0100-83582003000200006.
The intensity of the potential allelopathic effects depends on factors either related to the donor or receiver species. This research analyzes the variations on the allelopathic effect intensities of calopo (Calopogonium mucunoides) in relation to age of the donor plants (2, 4, 6, 8, 10 and 12 weeks after emergence) and to seed density of the receiver species (500, 1,000, 2,000, 3,000 and 4,000 seeds per m2). At each assigned age, plants were harvested and divided into shoot and root. The potential allelopathic effects were determined on the germination rates of the following weed seeds: Mimosa pudica, Urena lobata, Senna obtusifolia and Senna occidentalis. The intensity of the allelopathic effects was inversely related to the seed density increase. The effect was more intense for large-seeded (Urena lobata and Senna obtusifolia) than for small-seeded species (Mimosa pudica and Senna occidentalisfedegoso). Age was very important for the allelopathic effects of calopo. Calopo shoots showed increasing allelopathic effects with age, showing maximum effects at the age of four weeks. For roots, those effects increased until plants were 12 weeks old, when the values were higher than those observed for shoots. These results suggest that the forage legume calopo could be managed to maximize its allelopathic potential.
Keywords : allelopathy; germination; inhibition; legume; weeds.