Short-term partitioning of Cd recently taken up between sunflowers organs (Helianthus annuus) at flowering and grain filling stages: effect of plant transpiration and allometry

Abstract

This work concentrated on understanding the allocation of Cd recently taken up between the organs of sunflower at early and middle reproductive growth stages. The roles of transpiration and allometry were investigated. Sunflowers were grown hydroponically in greenhouse, being exposed to low concentrations of Cd (pCd2+ = 11.03). At flower bud and grain filling stages, plants were exposed for three days to 111Cd and at the same time, subjected or not to fans to increase the transpiration. The partitioning of 111Cd between plant organs measured by high resolution ICP-MS was then modelled. Although the use of fans increased the plant water uptake and transpiration by about 20%, there were no significant effects on the partitioning of recent Cd. Most of the recent Cd was recovered in roots (60%) and only 2.8% were found in seeds (0.8% for the husk and 2.0% for the almonds). The sequestration of recent Cd in a plant organ was successfully explained by its biomass and except for leaves, by the biomass of other organs acting as competitive sinks. This work proposes a modelling approach for the partitioning of the labelled Cd between plant organs in sunflower.