PLANT NUTRIENTS
Plant Nutrition.
Plants
use inorganic minerals for nutrition, whether grown in the field or in a
container. Complex interactions involving weathering of rock minerals, decaying
organic matter, animals and microbes take place to form inorganic minerals in
soil. Roots absorb mineral nutrients as ions in soil water. Many factors
influence nutrient uptake for plants. Ions can be readily available to roots or
could be tied up by other elements or the soil itself. Soil too high in pH
(alkaline) or too low in pH (acidic) makes many minerals unavailable to
plants.There are 20 mineral elements essential for plant growth.The rest of the
elements are required in trace amounts(micronutrients).Studies have also shown
that a number of other mineral elements are beneficial to the growth of plants
and are required for some plants.
MACRONUTRIENTS
1)NITROGEN:Nitrogen(N) is
taken up by plants as nitrate (NO3-) or ammonium (NH4+)
ions. It is utilized by plants to synthesize amino acids, the building blocks
of proteins. The protoplasm of all living cells contains protein. Nitrogen is
also required by plants for other vital compounds, such as chlorophyll, nucleic
acids, and enzymes. Over applications of nitrogen will be
detrimental to growth.
Symptoms of N Deficiency
Slow growth; stunted plants.
Yellow-green color (chlorosis).
Death (necrosis) of tips and margins of leaves,
beginning with more mature leaves.
2)PHOSPHORUS:Phosphorus (P)
is taken up by plants as ortho-phosphate PO4-. Phosphorus is present in
all living cells. It is utilized by the plant to form nucleic acids (DNA and
RNA).Through energy-rich linkages (ATP and ADP), it is involved in the storage and
transfer of chemical energy used for growth and reproduction. Phosphorus
stimulates seedling development and root formation. It hastens maturity and
promotes seed production. Phosphorus supplementation is required most by plants
under the following circumstances: (1) cold weather, (2) limited root growth
period, and (3) rapid vegetative growth.
Symptoms of P Deficiency
Slow growth; stunted plants.
Purplish coloration on foliage of some plants (older
leaves first).
Dark green coloration.
Delayed maturity and Poor fruit or seed development.
3)POTASSIUM:Potassium (K) is
taken up by plants in the form of potassium ions (K+). It remains in ionic
form within cells and tissues. Potassium is essential for translocation of
sugars and for formation of starch. It is required in the opening and closing
of stomata by guard cells. Potassium promotes root growth; produces larger,
more uniformly distributed xylem vessels throughout the root system; and
increases plant resistance to disease. Potassium increases size and quality of
fruits, nuts, and vegetables and improves winter hardiness of perennials. Plants
that produce large amounts of carbohydrates have a high potassium requirement.
Symptoms of K Deficiency:
Slow growth.
Tip and marginal chlorosis.
Weak stems and stalks.
Small fruit or shriveled seeds.
4)CALCIUM:Calcium (Ca) is
taken up by plants as the calcium ion (Ca++). A structural
nutrient, it is an essential part in cell walls and membranes and is
required for the formation of new cells. For this reason, early season
availability of supplemental Calcium has a distinct effect on fruit set.Once
deposited in plant tissues, Calcium is not remobilized.Therefore, young tissue
is affected first under conditions of deficiency. Since Calcium is not
mobile, the requirements of a crop for Ca++ after
early fruit set are commonly supplied in the form of nutritional sprays.
Symptoms of Ca Deficiency:
“Tip burn” of young leaves.
Death of growing points (terminal buds).
Root tips also affected and abnormal dark green
appearance of foliage
Premature shedding of blossoms and buds and Weakened
stems.
Water-soaked, discolored areas on fruits–blossom-end
rot of tomatoes, peppers, and melons; bitter pit or cork spot of apples and
pears.
5)MAGNESIUM: Plant uptake of magnesium
is in the form of the magnesium ion (Mg++).The chlorophyll molecule,
which is essential for photosynthesis, contains magnesium. Magnesium (Mg)
serves as an activator of many plant enzymes required in growth processes.
Magnesium is mobile within plants and can be readily translocated from older to
younger tissue when it is deficient. Plants need magnesium to balance the
generally high use of potassium from fertilizers and manure.
Symptoms of Mg Deficiency:
Interveinal chlorosis in older leaves
Curling of leaves upward along margins.
Marginal yellowing, with green “Christmas tree” area
along mid-rib of leaf.
6)SULPHUR: Sulphur (S) is
utilized in the form of sulfate ions (SO4=).
Sulphur may also be absorbed as sulphur dioxide (SO2) from the air
through leaves in areas where the atmosphere has been enriched with sulphur
compounds. It is not readily available from wettable sulphur which is in the
form of elemental sulphur. Sulphur is a constituent of three amino acids
(cystine, methionine and cysteine) and is therefore necessary for protein synthesis.
It is essential for nodule formation on legume roots. Sulphur is present in oil
compounds responsible for the characteristic odors of plants such as garlic and
onion.
Symptoms of S Deficiency:
Retarded growth rate and delayed maturity.
Young leaves light green to yellowish color.In some
plants, older tissue may be affected.
Small and spindly plants.
MICRONUTRIENTS
7)ZINC: Zinc (Zn) is
taken up by plants as the zinc ion (Zn++) and is an essential
constituent of several important enzyme systems in plants. It controls the
synthesis of indoleacetic acid, an important plant growth regulator.
Terminal growth areas are affected first when zinc is deficient.
Deficiency is most common on soils with neutral or alkaline pH that are sandy
or have low organic matter content (including cut areas) and are very
high in available phosphorus.
Symptoms of Zn Deficiency:
Decrease in stem length and rosetteing of terminal
leaves.
Reduced fruit bud formation.
Mottled young leaves (interveinal chlorosis).
Dieback of twigs after first year.
8)IRON:Iron (Fe) is taken
up by plants as ferrous ions (Fe++) and is required for the
formation of chlorophyll in plant cells. It serves as an activator for
biochemical processes, such as respiration, photosynthesis, and
symbiotic nitrogen fixation. Iron deficiency can be induced by high
levels of manganese or high lime content in soils. Deficiencies are common in
high pH soils, in situations with poor aeration, or when high levels of
zinc or manganese are present.
Symptoms of Fe Deficiency:
Interveinal chlorosis of young leaves,Veins remain
green
Twig dieback.
In severe cases, death of entire limbs or plants.
9)MANGANESE: Mn uptake is in
the form of the ion Mn++.Manganese serves as an activator for
enzymes in plant growth processes. It assists iron in chlorophyll formation. High
concentrations of manganese in plants may induce iron deficiency. Manganese is generally
required with zinc in foliar spraying of commercial citrus. Other tree crops
may show deficiencies.
Symptoms of Mn Deficiency:
Interveinal chlorosis of young leaves.
Gradation of pale-green leaf coloration, with darker
color next to veins. No sharp color distinction between veins and interveinal
areas .
10)COPPER:Plant uptake of
copper is in the ionic form (Cu++). Copper serves as an
activator of numerous plant enzymes and plays a role in the development of
plant pigments that influence color. A copper deficiency interferes with
protein synthesis. Copper deficiency has been observed on trees and vines
growing on organic soils and sands.
Symptoms of Cu Deficiency:
Stunted growth.
Dieback of terminal shoots in trees.
Poor pigmentation.
Wilting and eventual death of leaf tips.
Formation of gum pockets around central pith in
oranges.
11)BORON:Boron (B) is
predominately in solution as boric acid, H3BO3, and is
taken up by plants in this form. It functions in the differentiation of
meristematic cells. Boron is also involved in regulating metabolism of
carbohydrates in plants. Nearly all fruiting crops have a high demand for boron
in the early fruiting stage. Foliar applications are an effective way to meet
this demand at this critical growth state. Recent research has shown that boron
is effective in increasing pollen viability, thus contributing to increased
fruit set. When boron is deficient, cells may continue to divide, but
structural components are not differentiated.
Symptoms of B Deficiency:
Death of terminal growth, causing lateral buds to
develop, producing a “witch’s broom” effect.
Thickened, curled, wilted and chlorotic leaves.
Soft or necrotic spots in fruit or tubers.
Reduced flowering or improper pollination.
12)MOLYBDENUM:Molybdenum (Mo)
is taken up by plants as the molybdate ion (MoO4=). It is
required by plants for the utilization of nitrogen. Nitrate nitrogen is
converted to amino acids by the nitrate reductase enzyme; this enzyme
requires molybdenum. In addition, molybdenum is required for the
symbiotic fixation of nitrogen by legumes.
Symptoms of Mo Deficiency:
Stunting and lack of vigor. This is similar to
nitrogen deficiency, because of the key role of molybdenum in nitrogen
utilization.
Marginal scorching and cupping or rolling of leaves.
“Whiptail” of cauliflower.
Yellow spotting of citrus.
13) Chlorine: Chlorine is
involved in osmoregulation, the regulation of movement of water and other
solutes into and out of cells. Chlorine is essential for cell
division in leaves and in the regulation of opening and closing of stomata.
Chlorine is also involved in the photosynthetic evolution of oxygen and
nitrogen metabolism. High levels of chlorine can be severely detrimental to
plant growth.
Symptoms of Cl-
Deficiency
Deficiency symptoms include
wilting of leaves, chlorosis, and stunted root growth.
14) Nickel has recently been determined to be an essential trace
element for plants by the Agricultural Research Service (ARS) in Ithaca, New
York. It is required for the enzyme urease, which most plants use to break down
urea into usable forms of nitrogen. Nickel is also a necessary component
for the function of other enzymes. Nickel is essential for iron absorption.
Seeds require nickel in order to germinate.
Symptoms of Ni
Deficiency
Plants grown without an
adequate supply of nickel will gradually reach a deficient level at about the
time they mature and begin reproductive growth.
Beneficial Micronutrients:
15)Sodium is involved in osmotic (water movement) and ionic
balance and is required for some plants.
16)Cobalt is required for nitrogen fixation in legumes and in
root nodules of nonlegumes because it is a component of enzymes essential for
nitrogen fixation. Deficient levels could result in nitrogen deficiency
symptoms.
17)Silicon is found as a component of cell walls. Plants with
supplies of soluble silicon produce stronger, tougher cell walls creating a
mechanical barrier to the mouth parts of piercing and sucking insects. Silicon
significantly enhances plant heat, drought and cold tolerance. Foliar sprays of
silicon have also shown benefits reducing populations of aphids on field crops.Silicon
is known to be essential to some members of poaceae (grasses) but has shown
benefits to a wide variety of plants.
YOU CAN ALSO VISIT
https://www.biologicalworld.in/2021/11/brazil-nuts-and-human-mazes-to-amazon.html
https://www.biologicalworld.in/2021/11/a-review-on-diversity-of-woody-edible.html
https://www.biologicalworld.in/2021/10/c-dna-library-protocol-and-utility.html
https://www.biologicalworld.in/2021/10/genomic-dna-library.html
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