Chloroplasts in plants are most sensitive to Mn deficiency, which results in pale plants and is, to some degree, similar to iron (Fe) and magnesium (Mg) deficiencies. However, symptoms of Mn deficiency can be quite characteristic.
In wheat, symptoms appear first in new leaves, which become pale and limp in contrast to the old leaves. Light grey flecking and striping then appear at the base of the youngest fully opened leaf. Under severe deficiency, the new growth may emerge with this flecking and striping over the entire length of the leaf. Although the striping is interveinal, it differs from Fe deficiency in its irregularity and in the flecking associated with it. In time these new leaves lose more chlorophyll, particularly in the lower half of the leaf where necrosis set in and they collapse. By this symptom stage, they have become middle leaves.
Severe deficiency in the field reflects the above symptoms with some additional withering of new shoots. In the field, as with Fe deficiency, Mn deficiency can be induced on calcareous soils or after heavy applications of lime. Mn deficiency shows up as patches of pale, floppy wheat in an otherwise green healthy crop; symptoms may be worse in compacted areas, such as wheel tracks.