Original research articlePartitioning of nutrients and non-essential elements in Swiss chards cultivated in open-air plots

- No toxic element was accumulated in aboveground organs, except Cd.
- Younger plants were richer in nutrients, with low concentrations of toxic elements.
- Application of fertilisers influenced on the time course of elements accumulation.
- Organic practices enhanced nutrient content in plants and limited Cd accumulation.

The uptake of metals by plants and their partitioning between different organs is an important issue in fields like plant ecology, phytochemistry, phytoremediation and, in the case of plants with edible parts, food quality. In this work a five-month field experiment was carried out to investigate the uptake and partitioning of 20 elements (Mg, K, Ca, Na, Mn, Fe, Co, Cu, Zn, Mo, Sr, Ba, Al, Ti, V, Cr, As, Cd, Tl and Pb) by Swiss chards (Beta vulgaris). The effect of the harvesting time on the accumulation of these elements in roots, stalks and leaf blades was studied using plants cultivated in two different but adjacent air-open plots subjected to conventional or organic farming techniques. Plants were collected at six growth stages during their production cycle and samples were analysed by ICP-MS after microwave assisted acid digestion. Toxic elements (except Cd) were mainly immobilised in roots, whereas essential elements were translocated to aboveground organs. In general, the element concentrations in plant organs decreased with time. The use of organic fertilisers promoted the presence of nutrients in blades and stalks. Pb and Cd concentrations in the edible parts were always below the maximum levels set by the European Union.