Plants growing in urea sprayed but Mg deficient soil will show

Plants growing in urea sprayed but Mg deficient soil will show yellowing of leaves.
Magnesium is the central core of the chlorophyll molecule in plant tissue. Thus, if Mg is deficient, the shortage of chlorophyll results in poor and stunted plant growth along with yellowing of leaves. Magnesium also helps to activate specific enzyme systems.
A plant growing in magnesium-deficient soil would show chlorosis inspite of being sprayed with urea (nitrogen).