Molybdenum (Mo) is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known into prehistory, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.
Molybdenum is an essential element playing a very important role in the growth and development of plants. In the majority of agricultural soils, the content of molybdenum is somewhere in the range of 0.6 ppm – 3.5 ppm with an average of 2 ppm.
Plants typically take up molybdenum in the form of molybdate. One controlling factor as to the amount of molybdenum that is available for the plants is the pH in the soil. The adsorption rate at neutrality is extremely low. The rate only increases as the pH lowers. That is why if the soil is acidic, there is more molybdenum (Mo) readily available for plant use. Molybdenum is vital for plant growth for a number of reasons. The primary reasons that crops and plants require a sufficient supply of Mo is because it is part of the enzymes nitrate reductase and nitrogenase (enzymes that reduce nitrogen to usable forms.) Of all crops, legumes are those that require the highest amount of molybdenum.
Many of these discoveries are new but the necessity for molybdenum in plants for healthy growth has been recognized for many years. In fact, Arnon and Stout in 1939 first discovered and identified molybdenum as an essential element. That is 75 years in which there have been studies and examinations performed as to what the parameters are for molybdenum in plant growth. So, what is it exactly that makes this element so vital to your plants? Why is it so important that you know about it or that you understand it better? What roles does it actually play in crop yields and what are the defects if you don’t have sufficient levels present in your soil?
In the studies and examinations that were performed, the defects that are presented with deficiencies of molybdenum in the plant soil and plant tissues were discovered. One problem that is caused by an insufficient amount of molybdenum is a restriction or retardation of plant growth. In fact, a lot of the symptoms that are caused by molybdenum deficiency have visual symptoms similar to a lack in nitrogen. This makes sense since molybdenum, is necessary for converting nitrogen into it’s usable form.
Flowering can be slowed or restricted if there is not enough Mo in the soil available for the plant to absorb. Leaves can become pale or eventually even wither if the deficiency is severe enough. Also, irregularities in the formulation of leaf blades are another one of the more common visual symptoms. However, all of these different plant problems are caused because of a necrosis (a form of cell injury that results in the premature death of cells in living tissue by self-digestion) in the tissue that is largely due to a lack of the element molybdenum.
Molybdenum (Mo) is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known into prehistory, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.
Molybdenum is an essential element playing a very important role in the growth and development of plants. In the majority of agricultural soils, the content of molybdenum is somewhere in the range of 0.6 ppm – 3.5 ppm with an average of 2 ppm.
Plants typically take up molybdenum in the form of molybdate. One controlling factor as to the amount of molybdenum that is available for the plants is the pH in the soil. The adsorption rate at neutrality is extremely low. The rate only increases as the pH lowers. That is why if the soil is acidic, there is more molybdenum (Mo) readily available for plant use. Molybdenum is vital for plant growth for a number of reasons. The primary reasons that crops and plants require a sufficient supply of Mo is because it is part of the enzymes nitrate reductase and nitrogenase (enzymes that reduce nitrogen to usable forms.) Of all crops, legumes are those that require the highest amount of molybdenum.
Flowering can be slowed or restricted if there is not enough Mo in the soil available for the plant to absorb. Leaves can become pale or eventually even wither if the deficiency is severe enough. Also, irregularities in the formulation of leaf blades are another one of the more common visual symptoms. However, all of these different plant problems are caused because of a necrosis (a form of cell injury that results in the premature death of cells in living tissue by self-digestion) in the tissue that is largely due to a lack of the element molybdenum.
MOLYBDENUM DEFICIENCY SYMPTOMS
Since the most important function of molybdenum in plant metabolism is in the NO3- (nitrate) reduction, molybdenum deficiency resembles nitrogen deficiency. Plants suffering from molybdenum deficiency are restricted in growth; their leaves become pale and eventually wither. Flower formation may be restricted. In dicotyledons a drastic reduction in size and irregularities in leaf blade formation (whiptail) are the most typical visual symptoms. These are caused by local necrosis in the tissue and insufficient differentiation of vascular bundles at early stages of leaf development.