MINERAL NUTRITION 199
are a part of the structural component of the cell and hence are not easily
released.
Significance
This aspect of mineral nutrition of plants is of a great significance
and importance to agriculture and horticulture.
The kind of deficiency symptoms shown in plants include chlorosis,
necrosis, stunted plant growth, premature fall of leaves and buds, and
Inhibition of cell division.
Chlorosis is the loss of chlorophyll leading to
yellowing in leaves. The deficiency of elements causes this symptom
N, K, Mg, S, Fe, Mn, Zn and Mo. Likewise, necrosis, or death of tissue,
particularly leaf tissue, is due to Ca, Mg, Cu, K. Lack or
low level of N, K, S, Mo causes inhibition of cell division. Some elements
like N, S, Mo delay flowering if their concentration in plants is low.
You can see from the above that the deficiency of any factor can
Cause multiple symptoms, and that the deficiency of several different elements may cause the same symptoms. Hence, to identify
the deficient element, one has to study all the symptoms developed in various parts of the plant and compare them with the available
standard tables. We must also be aware that different plants also respond
differently to the deficiency of the same element.
12.2.4 Toxicity of Micronutrients
The requirement of micronutrients is always in low amounts while their
moderate decrease causes the deficiency symptoms, and an average increase
causes toxicity. In other words, there is a narrow range of concentration at
which the elements are optimum. Any mineral ion concentration in tissues
that reduces the dry weight of tissues by about 10 percent is considered.
Toxic. Such critical concentrations vary widely among different
micronutrients. The toxicity symptoms are challenging to identify. Toxicity levels
for any element also go for other plants. Many times, excess of a component may inhibit the uptake of another aspect. For example, the
prominent symptom of manganese toxicity is the appearance of brown
spots surrounded by chlorotic veins. It is essential to know that.
Manganese competes with iron and magnesium for uptake and with
magnesium for binding with enzymes. Manganese also inhibits calcium
translocation in the shoot apex. Therefore, excess manganese may
induce deficiencies of iron, magnesium, and calcium. Thus, what appears
to be manganese toxicity may be the deficiency
symptoms of iron, magnesium, and calcium. Can this knowledge be of some
importance to a farmer? a gardener? or even for you in your kitchen garden?
12.3 MECHANISM OF ABSORPTION OF ELEMENTS
Much of the studies on the mechanism of absorption of elements by plants
Has been carried out in isolated cells, tissues, or organs. These studiesMINERAL NUTRITION 199
are a part of the structural component of the cell and hence are not quickly
released. This aspect of the mineral nutrition of plants is of great significance
and importance to agriculture and horticulture.
The kind of deficiency symptoms shown in plants include chlorosis,
necrosis, stunted plant growth, premature fall of leaves and buds, and
Inhibition of cell division. Chlorosis is the loss of chlorophyll leading to
yellowing in leaves. The deficiency of elements causes this symptom
N, K, Mg, S, Fe, Mn, Zn and Mo. Likewise, necrosis, or death of tissue,
particularly leaf tissue, is due to Ca, Mg, Cu, K. Lack or
low level of N, K, S, Mo causes inhibition of cell division. Some elements
like N, S, Mo delay flowering if their concentration in plants is low.
You can see from the above that the deficiency of any element can
Cause multiple symptoms, and that the deficiency of several different elements may cause the same symptoms. Hence, to identify
the deficient element, one has to study all the symptoms developed in various parts of the plant and compare them with the available
standard tables. We must also be aware that different plants also respond
differently to the deficiency of the same element.
12.2.4 Toxicity of Micronutrients
The requirement of micronutrients is always in low amounts while their
moderate decrease causes the deficiency symptoms and an average increase
Causes toxicity. In other words, there is a narrow range of concentration at
which the elements are optimum. Any mineral ion concentration in tissues
that reduces the dry weight of tissues by about 10 percent is considered
toxic. Such critical concentrations vary widely among different
micronutrients. The toxicity symptoms are challenging to identify. Toxicity levels
for any element also go for other plants. Many times, excess of a component may inhibit the uptake of another aspect. For example, the
prominent symptom of manganese toxicity is the appearance of brown.
Spots surrounded by chlorotic veins. It is essential to know that
manganese competes with iron and magnesium for uptake and magnesium for binding with enzymes. Manganese also inhibits calcium
translocation in the shoot apex. Therefore, excess manganese may
induce deficiencies of iron, magnesium, and calcium. Thus, what appears.
As symptoms of manganese toxicity may be the deficiency
symptoms of iron, magnesium, and calcium. Can this knowledge be of some
importance to a farmer? a gardener? or even for you in your kitchen garden?
12.3 MECHANISM OF ABSORPTION OF ELEMENTS
Much of the studies on the mechanism of absorption of elements by plants
have been carried out in isolated cells, tissues, or organs. These studies
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