Plant nutrient elements defined from the plant's perspective

Official URL: https://dx.doi.org/10.1007/s11104-026-08946-1

Background: Definitions of plant nutrient elements, historically anchored in the essentiality criteria of Arnon and Stout, have provided a robust basis for identifying essential mineral nutrients. Yet, they are increasingly challenged by evidence for context-dependent benefits of additional elements and by regulatory demands that tie fertiliser constituents to officially recognized ‘nutrients’. Recent proposals to expand the nutrient concept to include beneficial elements and nutrient effects on quality attributes of harvested products have intensified this debate. Scope: This opinion paper evaluates such proposed revisions from a plant-centred perspective. We argue that, while inclusion of elements that improve plant performance under defined conditions is justified, incorporating the broadly used and target-group-dependent concept of ‘quality’ introduces ambiguity and may foster misleading claims, including alleged ‘quality improvements’ driven by stress responses or concentration effects. To improve precision, we propose the term ‘conditionally beneficial elements’ for elements that enhance growth, development or reproduction only in specific species and/or under specified growth conditions. Conclusions: Building on classical essentiality while acknowledging practical experimental constraints, we advance an updated definition for vascular plants, namely: A plant nutrient element, considering natural or managed environments, is essential if deprivation impairs growth, development, or reproduction, or conditionally beneficial if it improves these performance traits in a given species under specified conditions. In both cases, the element must have an established performance-improving role in plant biology. The essential mineral elements comprise the macronutrients N, P, S, K, Ca, and Mg and the micronutrients Fe, Mn, Zn, Cu, Ni, B, Cl, and Mo, whereas Na, Si, Co, Al, and Se are currently classified as conditionally beneficial elements. We argue that this definition supports conceptual clarity in research as well as recognition of nutrient elements in fertiliser legislation, while protecting against unfounded claims.