The deficiency of certain nutrients is first visible in young growing parts because these elements are immobile within the plant.
Two such important plant nutrients are Calcium and Sulphur.
Calcium is essential for cell wall formation and growth of root and shoot tips.
A deficiency of calcium leads to stunted growth, death of growing points, and disorders like blossom end rot in tomatoes.
Sulphur is needed for protein synthesis and chlorophyll formation.
Its deficiency shows up as yellowing or chlorosis in young leaves while older leaves may remain green.
Since these nutrients cannot be easily translocated from older to newer tissues, symptoms appear first in young parts.