Provide information about essential mineral elements for plants and state the criteria for essentiality.

(N/A) $\Rightarrow$ Most minerals present in the soil can enter plants through their roots. In fact,more than $60$ of the $105$ elements discovered so far are found in different plants.
$\Rightarrow$ Some plant species accumulate selenium,while others store gold.
$\Rightarrow$ Plants growing near nuclear test sites can take up radioactive strontium.
$\Rightarrow$ Modern techniques can detect minerals even at very low concentrations,such as $10^{-8} \text{ g/mL}$.
$\Rightarrow$ The criteria for the essentiality of an element are as follows:
$(a)$ The element must be absolutely necessary for supporting normal growth and reproduction. In the absence of the element,plants cannot complete their life cycle or set seeds.
$(b)$ The requirement of the element must be specific and not replaceable by another element. In other words,the deficiency of one element cannot be met by supplying another element.
$(c)$ The element must be directly involved in the metabolism of the plant.
$\Rightarrow$ Based on these criteria,only a few elements have been found to be absolutely essential for plant growth and metabolism.