Dry matter and nutrient partitioning in Castor plants in two growing seasons
The aim of the present study was to evaluate dry matter partitioning and macro- and micronutrient accumulation and distribution in small-sized castor plants grown in season and off-season. The experiments were conducted during the 2005-2006 season and in the 2006 off-season in an Oxisol. A completely randomized block design was used, with eight replications. Plots consisted of plant sampling periods, which were conducted in the vegetative period (17 days after emergence - DAE), the grain fill period (between 73 and 80 DAE) and at end of the cycle (120 DAE). Castor leaves accumulated most of dry matter (DM) and macro- and micronutrients in the vegetative period, regardless of the growing period. In the following cycle periods, most of biomass and nutrients were located in the reproductive structures and grains, especially in the off-season crop. It was concluded that leaves and stems are strong nutrient sinks in the castor plant in season crops, while lower water availability during off-season induces plants to use physiological mechanisms to allocate more resources (biomass and nutrients) for their reproduction.