This study was carried out to evaluate herbicide 2,4-D effects on plant growth, production of dry and green matter and grain productivity. The experiment was carried out from March to June 2006, in Rio Verde,GO in soil classified as Eutroferric Red Latosol. Pennisetum americanum (cultivar ADR 500) was manually sowed in area under no-till system. A space of 0.45 m was used, with 12 seeds being sown per meter. The experiment was arranged in a randomized block design, in a 4 x 4 factorial scheme, with four 2,4-D rates (0. 335, 670 and 1,005 g ha-1) applied 10 days after emergence [DAE] (3 leaves), 20 DAE (5 to 6 expanded leaves), 30 DAE (beginning of inflorescence emission) and 40 DAE (flowerage). Weeding was manually performed when necessary to eliminate weed interference effects. At 15 days after application, phytotoxicity symptoms were not detected in the plants, at any rate or plant stage. Green and dry matter of the plants decreased at roller point with herbicide rate increase; 2,4-D application did not influence grain production, regardless of dose amount used or application time .
selectivity; herbicide; straw; auxins
