💡 The presence or concentration of an element in a plant does not signify that elements essentiality to the plant. Plants are limited in which elements they are able to absorb, regardless of its essentiality or toxicity to its growth. Their selective uptake of elements can be to their own detriment depending on whether the elements they take up are toxic or inert. Therefore, determining a plants essential element can not be derived purely from a present elemental composition. Micro and macro nutrients are essential groups of nutrients that can reveal a plant’s requirement of an element. But what determines a plants essential elemental criteria? According to Marschner’s Mineral Nutrition of Higher Plants, there are three criterion that must be met in order for an element to be considered essential.
📌 The three criteria:
▶ An element’s presence in a plant is necessary for that plant to complete its lifecycle. Without that particular element, the plant can not complete its lifecycle.
▶ No other element can replace or substitute the function of an essential element.
▶ The element must be directly involved in the plant’s metabolism.
🎯If an element were to alleviate the toxic effects of another element, such as silicon for manganese toxicity, or the element were to replace another element, such as sodium for potassium, those elements could not be qualified as essential for plant growth. Most micronutrients are constituents of enzyme molecules and are therefore essential only in small concentrations. On the other hand, macronutrients are constituents of organic compounds, such as proteins and nucleic acids.
📷 Image: The 16 essential elements required for plant life.