Agriculture Reference
In-Depth Information
macronutrients (N, P, K, Mg, Ca, S, Si). After entering the plant cell, mineral
nutrients need to be translocated to different locations for their metabolism.
Table
4.1
summarizes the list of all macro- and micronutrients and their role and
Table 4.1 Role of different mineral nutrients and their deficiency symptoms
Mineral nutrient and its
availability
Physiological role
Deficiency symptoms
Nitrogen: present mainly in
organic form (98 %) in soil.
Remaining 2 % inorganic part
comprises of NH
4
+
(immo-
bile) and NO
3
(highly
mobile) forms. Soil nitrogen is
often lost when crops are
harvested and plant material is
removed from the soil
Basic component of proteins
and genetic material and
hence required by the plant in
greatest amount
Yellowing of leaves (chloro-
sis) and subsequent falling
Potassium: present as cation
(K
+
)
Involved in maintaining the
turgor pressure of plant cells,
enhancing the disease resis-
tance and activates enzymes
involved in photosynthesis
and respiration; affects the
synthesis of simple sugars,
starch, and proteins, translo-
cation of carbohydrates,
reduction of nitrates, normal
cell division, and stomatal
movements
Mottling leading to necrosis
and higher susceptibility to
diseases
Calcium: present as Ca
2+
ions
Intracellular messenger in the
cytosol, synthesis of new cell
wall, cell division, controlling
membrane structure and
function
Deficiency is rare in nature,
but if deficient, then causes
poor development of root,
necrosis and curling of
leaves, fruit cracking, poor
fruit storage, etc.
Magnesium: present as diva-
lent cation (Mg
2+
), constituent
of chlorophyll molecule
Activation of enzymes,
involved in various physio-
logical and biochemical pro-
cesses like photosynthesis and
respiration
Chlorosis, mainly in older
leaves
Phosphorous: present in
organic and mineral P forms in
soil. Plants obtain P as
orthophosphorous anion
(HPO
4
2
and H
2
PO
4
) which
are present in less amount in
soil
Important constituent of
nucleic acid, phospholipid
component of membranes and
ATP
Necrotic spots, dwarf/ stunted
growth, distinct purple color
develops in leaves
Sulfur: present as sulfides
(S
), elemental sulfur (S
0
),
and sulfate (SO
4
2
) forms in
soil of which SO
4
2
form is
absorbed by plants
Component of amino acids
and vitamin A
Decrease in leaf chlorophyll
content, protein synthesis,
leaf chlorosis
