Deficiency symotoms of nitrogen and potassium are visible first in:
As discussed in
Potassium Function -
Activates many enzymes associated with pump in active transport , opening and closing of stomata, cell's turgidity.
Deficiency stunted growth, mottled appearance, short internodes, loss of apical dominance.
Nitrogen Function -
Synthesis of amino acids, proteins, nucleic acids, vitamins, harmones coenzymes, chlorophyll, NAD, NADP, FMN, FAD
Deficiency causes chlorosis, red leaf of cotton,development of anthocyanin.
Deficiency of nitrogen and potassium causes chlorosis and mottled appearance respectively in senescent leaves