Resumo

RINCON, Álvaro; LIGARRETO, Gustavo A.  e  SANJUANELO, Danny. Growth of corn and grasses (Brachiaria sp.) established in monoculture and associated with acid soils of the Piedemont Plains of Colombia. Agron. colomb. [online]. 2007, vol.25, n.2, pp.264-272. ISSN 0120-9965.

The experiment was carried out in the Piedemont Plains of Colombia, where the establishment and recuperation of grasslands associated with corn culture is a productive option for the livestock farmers of the region. Under a randomized complete block design with four replicates, the establishment of corn in monoculture and association with grasses (Brachiaria decumbens, Brachiaria cv. Mulato and Toledo (Brachiaria brizantha)) was evaluated in order to determine the existence of competition and its effect on the grain yield in corn and forage production in grasses. The period of evaluation was from 15 up to 90 days after sowing (d.a.s.), a time period, in which corn was already in drying process. The growth of corn was not affected by the presence of grasses, being characterized with leaf area index (LAI) equal to 3 at 45 d.a.s. and the highest dry weight production of 29 g DM/plant at 66 d.a.s. At the same time, the presence of corn do affected the growth of grasses during the whole period of evaluation. The leaf area and dry weight of grasses associated with corn were reduced on 50% as compared with those of grasses grown without corn, so that at 75 d.a.s. the LAI was 1.0 and 2.6 in grasses associated with corn or monoculture, respectively. In any case, the dry weight was of 68 g·m^-2 and 140 g·m^-2 for the same treatments. The cultivation of corn with grasses is a good option for the establishment or renovation of grasslands because the corn yields were not affected by the grass presence. The grasses associated with corn presented a slow growth during the first 75 d.a.s., without affecting the growth of corn, however, during the 15 following days, the LAI and dry weight were increased on 170% and 53%, respectively, due to natural drying of corn plants that allowed the penetration of direct solar radiation.

Palavras-chave : association; crops; leaf area index; growth; dry weight.

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