Functions of Mo :- Visual symptoms :- Predisposing factors:- Corrective measures :- Molybdenum requirement of plants is lower than that of any other mineral nutrients. It is a component of enzymes and in oxidized state it exists as Mo (VI) and it gets reduced to Mo (V) and Mo (IV). Molybdenum is a co-factor of enzymes nitrate reductase and nitrogenase in higher plants. Molybdenum has similar catalytic functions in both enzymes and molybdenum requirement depends on the mode of nitrogen supply. Generally molybdenum requirement for nitrogen fixation is greater than nitrate reduction. The critical deficiency level of molybdenum in the leaves of nitrate fed plants is usually far below 1mg per gram leaf dry weight. When nitrate is supplied in the absence of molybdenum, plants grow poorly with low chlorophyll content, low ascorbic acid content, but high nitrate levels in the leaves are common. In molybdenum deficient plants inorganic phosphorus increases as compared to organically bound phosphorus. Organic acids and amides accumulate and also pollen formation and fertilization of the ovule gets affected in Mo deficient plants. Drastic reduction and irregularities in leaf formation, insufficient differentiation of vascular bundles results due to Mo deficiency. Molybdenum deficiency results in yellowing and curling of the leaves. The veins remain light green in colour and chlorotic areas become puffed in appearance and up curling of the leaves are evident. Mo deficiency is not seen in tobacco. Mo deficiency can arise in acid soils (low pH) because of high Mo fixation in soils. Foliar application of molybdenum is required for correcting the acute deficiency but soil application or seed treatment also can be adopted.

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