An experiment was carried out to evaluate the genotypical differences on rates of nitrogen absorption, as related to root developmental patterns, on two rice (Oryza sativa L.) cultivars. The cultivars IAC 4440 and Comum Branco, adapted to irrigated and upland tillage respectively, were grown in nutrient solution, when seven harvests were performed at ten days intervals. Regardless the narrow differences between cultivars on root dry mass production, IAC 4440 showed greater total root surface area, with finer roots and higher specific root area, as a consequence of a more intensive tillering, associated with higher nitrogen concentration in leaves and stems. Nitrogen influxes into roots were significantly higher in Comum Branco between 35 and 55 days after planting, when differences on root developmental patterns of cultivars have initiated. The lower nitrogen influx of IAC 4440 was compensated by its greater production of root area, resulting in similar nitrogen accumulation rates on both cultivars.
growth analysis; Oryza sativa; root area
