Molybdenum deficiency

Deficiency symptoms of molybdenum (Mo) depend to some degree on the nitrogen (N) status of the plant. At low levels of applied N, the initial limp leaf symptoms in Mo-deficient plants contrast with the upright stture of Mo-adequate plants. Differences in color are not evident. However, with high levels of applied N, Mo-deficient wheat plants are much paler green than those adequately supplied with Mo. When very high N-rates are applied to Mo-deficient plants, tip scorching of old leaves may occur. This is because Mo is a constituent of the enzyme nitrate reductase and nitrate may accumulate to toxic concentrations within the old leaves.

A characteristic symptom of Mo deficiency is a longitudinal yellow striping mostly on the middle leaves. Plants become very pale green and limp when compared to Mo-adequate plants. The old leaves remain greener than the remainder of the plant, although with time some plants develop necrosis of the tips and margins of the old and middle-aged leaves. New growth remains normal, but under severe deficiency delayed maturity will occur and very deficient plants can produce empty heads.

In the field, Mo deficiency can decrease yields by 30% before symptoms become apparent. It is difficult to diagnose mild deficiency, but there is a general paling of all but the oldest leaves and a limp appearance of most leaves as if in the early stages of drought stress. Delayed maturity and white and empty heads may be apparent.

Molybdenum Deficiency Molybdenum Deficiency Molybdenum Deficiency