Diagnosis and recommendation integrated system and nutritional balance index reveal Cd-induced nutritional disorders in Panicum maximum assayed for Cd phytoextraction

Abstract

The identification of nutritional disorders in plants induced by cadmium (Cd), based only on nutrient concentration, can fail and conceal links with biochemical and physiological events. In this study, the diagnosis and recommendation integrated system (DRIS) and nutritional balance index (NBI) were evaluated as auxiliary tools for diagnosing nutritional disorders in two Panicum maximum genotypes (Tanzania and Massai) which have contrasting behaviors for Cd translocation from roots to shoot. The correlation between nutritional disorders and Cd translocation in these plants was also checked. N, P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn concentrations in shoots of both grasses were extracted from studies previously published to form the database and develop DRIS, in which P. maximum cv. Tanzania was exposed to 0, 1, and 2 mmol L⁻¹ of Cd, for eleven days, while P. maximum cv. Massai was exposed to 0, 0.1 and 0.5 mmol L⁻¹ of Cd, for nine days. DRIS and NBI were obtained by calculations from nutrient concentrations in the shoot. Only P, S, and Zn concentrations in the shoot of P. maximum cv. Tanzania and P, K, S, Cu, and Fe in the shoot of P. maximum cv. Massai were Cd-disturbed from the point of view of nutrient concentration. However, DRIS revealed that the concentrations of Fe and Mn in the shoot of P. maximum cv. Tanzania exposed to Cd were considerably higher compared to other nutrients, enabling us to better understand certain biochemical and physiological Cd-induced events which occurred. Moreover, DRIS revealed that the Cd-induced nutritional disorders in the shoot of P. maximum cv. Massai were Cd-level dependent, and NBI confirmed that nutritional Cd-induced disorders in P. maximum increased when Cd translocation from roots to shoot was higher. In conclusion, DRIS and NBI revealed Cd-induced nutritional disorders that had previously been obscure. Therefore, their use as auxiliary tools for diagnosing Cd-induced nutritional disorders is recommended.

Keywords:

• DRIS
• forage grasses
• nutrient use efficiency
• nutritional diagnosis
• phytoremediation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by the Brazilian Federal Government Agency, Coordination for the Improvement of Higher Education Personnel – CAPES [grant number 1332394], by National Council for Scientific and Technological Development – CNPq [grant number 306403/2013-7], and by São Paulo Research Foundation – FAPESP [grant numbers 2012/12894-3, 2012/11859-0, 2014/16731-7, 2014/18735-0, 2015/21562-2, 2017/11299-8, and 2018/07190-3].