Con el objeto de evaluar el efecto de densidades de siembra y fertilizacion nitrogenada sobre el rendimiento de granos de arroz, Oryza sativa l., del cultivar CENTAURO, se esta blecieron ensayos durante el ciclo de riego 2006- 2007 en las tres principales zonas de produccion del pais. Se evaluaron tres niveles de densidad de siembra (Ds) y cuatro dosis de nitrogeno (DN). El diseno estadistico utilizado fue de bloques completos al azar con arreglo en franjas. Se evaluo rendimiento de granos kg ha-1, ajustado al 12% de humedad y caracteristicas secundarias. Se realizaron analisis de varianza, media y analisis multivariado de compo nentes principales (cp). los analisis individuales por localidad y conjunto detectaron diferencias altamente significativas (P≤ 01) para las DN en todas las localidades y diferencias significativas para la Ds solo en Barinas, la interaccion DNxDs resulto altamente significativa en Barinas y guarico, no asi en portuguesa, posible mente debido a la alta variacion experimental. Todos los resultados sugieren que el cultivar cENTAURo presenta una respuesta diferencial a la aplicacion de N (120 ≤ DN ≤ 200) kg ha-1 para el rendimiento de granos kg ha-1. El analisis conjunto de la varianza para DN, loc, DNxloc y DNxDs resulto significativo al 1% y 5%, respectivamente , con predominancia de las variancias de localidades, seguida de DNxloc, DN y DNxDs. El analisis de cp y la doble representacion (biplot) resultaron de gran utilidad para estudiar la interaccion de ambos factores (DNxDs)
In order to evaluate the effect of planting density and nitrogen fertilization on the grain yield, Oryza sativa L. of CENTAURO, trials were established during the 2006- 2007 irrigation cycle in the three main production areas of the country. The design was a randomized complete block arranged in stripes, the (DN) is located in the main plots and (Ds) in the secondary plots with three replications. grain yield was evaluated in kg ha-1, adjusted to 12% moisture. Analyses of variance were conducted individual and group, Tukey mean analysis and multivariate analysis of principal components. The analysis individually and group by location allowed to detect significant differences (P ≤ 0.01) for DN in all locations and significant differences Ds in Barinas, DNxDs interaction was highly significant in Barinas and guarico, while in portuguesa it was not detected possibly due to high experimental variation. All these results suggest that the cultivar cENTAURo presents a differential response to nitrogen application (120 ≤ DN ≤ 200) kg ha-1 for grain yield. The group analysis the sources of variation in DN, Loc, DNxDs and DNxLoc were significant at 1% and 5%, respectively. The variation is predominance in the locations, followed by DNxloc, DN and DNxDs. It was found that the principal components analysis and the use of dual representations (Biplot) are useful for studying the interaction of both factors (DNxDs