Why is that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs?
Plant requires various macro- and micro- elements for its normal growth, development and metabolic activities. Shortage of any of these essential elements below critical concentration can affect the growth of the plant and show morphological changes in the plant. These changes occur due to deficiency of one or more vital element and these morphological changes are referred to as deficiency symptoms. These deficiency symptoms can be seen in various parts of plant on the basis of mobility of the element. Deficiency symptoms of mobile elements like Nitrogen, Potassium are first visible in the mature organs as the plant actively transports these elements to the younger parts of the plant by breakdown of biomolecules in older parts and mobilising them to young developing tissues. Whereas elements like Calcium, that are present in the cell wall, are difficult to mobilise from old organs and can show deficiency symptoms in the younger parts of the plant.
