Descripción
The effect of four pre-planting treatments, a) intensive grazing the day before planting, b) cutting and burning a week before planting, c) use of herbicide three weeks before planting, and d) conventional plowing and harrowing on the establishment of the grasses: Tanner (Brachiaria radicans, Napper), African Stargrass cv. 171 (Cynodon plectostachyus (K. Schum) Pilger), Pentzii (Digitaria pentzii, Stent) and Signal grass (Brachiaria decumbens, Stapf) planted at distances of 0.50 x 0.50 m, 1.00 x 1.00 m, 1.50 x 1.50 m and 2.00 x 2.00 m and fertilized at the rate of 25 kg of N, 25 kg of P2O5 and 25 kg of K2O/hectare/year, was studied at Gualaca Research Station, using a 4 x 4 x 4 factorial design with two replicates. There were significant (P<.05) differences between preplanting treatments, between species and between planting distances. The average coverage was significantly (P<.05) higher in the herbicide pre-planting treatment, but it was similar to the conventional treatment; both of them were significantly better than the cutting and burning and intensive grazing treatments. Digitaria pentzii's coverage percentage was significantly higher (P<.05) than in the other species in all pre-planting treatments, Tanner and Signal grasses were intermediate, while African Stargrass showed the lowest percentage of coverage. Planting at 0.50 x 0.50 m excelled all other planting distances in regard to percentage of coverage, especially in the herbicide and conventional pre-planting treatments; planting at 2.00 x 2.00 m showed the poorest results, especially in the cutting and burning and intensive grazing treatments. The tendency to reduce the percentage of coverage as the planting distance was increased, was more marked in the grasses Tanner, Signal and African Stargrass. Total establishment costs per pre-planting treatments were B/.120.73 for intensive grazing, B/.159.80 for cutting and burning, B/.222.31 for herbicide, and B/.242.97 for conventional treatment. Under minimun tillage and fertilization conditions, in soils similar to those at Gualaca, aggressive species like Digitaria pentzii and Digitaria swazilandensis, using herbicides as pre-planting treatment for weed control, and planting at a distance of 0.50 x 0.50 m, are recomended. Descripción
En la estación Experimental de Gualaca se estudió el efecto de cuatro tratamientos de pre-siembra sobre el establecimiento de las gramíneas Táner (Brachiaria radicans, Napper), Estrella Africana cv. 171 (Cynodon plectostachyus (K. Schum) Pilger), Pentzii (Digitaria pentzii, Stent) y Señal (Brachiaria decumbens, Stapf). Se utilizó un diseño factorial 4 x 4 x 4 en parcelas sub-divididas con dos repeticiones. Se encontraron diferencias significativas (P<.05) entre tratamientos de pre-siembra, entre especies y entre distancias de siembra. La gramínea D. pentzzi superó en porcentaje de cobertura (P<.05) a las otras especies en todos los tratamientos de pre-siembra, las gramíneas Táner y Señal fueron intermedias y la hierba Estrella resultó inferior. La tendencia a mermar el porcentaje de cobertura, a medida que se incrementaba la distancia de siembra, fue mayor en las hierbas Táner, Señal y Estrella. En condiciones de labranza y fertilización mínima, en suelos similares a los de Gualaca, se recomiendan especies agresivas como la D. pentzii y D. swazilandensis, empleando tratamientos de pre-siembra con herbicidas y convencional, y sembrándolas a chuzo a distancias de 0.50 x 0.50 m.
Editorial
Instituto de Innovación Agropecuaria de Panamá