All of the following are elements whose deficiency symptoms first appear in the older tissues,except:

Top rot of tobacco is due to deficiency of

Heart rot of marigold is caused by the deficiency of

Which of the following is $NOT$ a deficiency symptom of mineral nutrition?

Absence of $Mg^{++}$ ions from plant tissue results in

Plants show certain morphological changes due to the absence of a specific element. These morphological changes are indicative of the deficiency of that particular element,which are called $........$ of the element.