Introduction to nutrition, nutrient and their importance on crop production
Nutrition :
-The supply and absorption of chemical compounds needed for growth and
metabolism of an organism.
Nutrient :
-Nutrients are substances required by an organism for their normal growth and
reproduction.
Plant Nutrient :
The plant nutrient is a “food” which is composed of certain chemical elements
often referred to as ‘plant nutrient’ or plant food elements considered very
essential for growth and development of plants.
Essential nutrients and their categories according to plant needs
-An essential nutrient element is the one which is required for the normal life cycle
of an organism and where functions cannot be substituted by any other chemical
compound.
Or
-The elements needed by the plant without which the plant is not able to survive
and complete its life cycle are called essential nutrient.
Essential nutrients are classified into two major groups based on relative
utilization or absorption by the plants. They are
A. Macro or Major Nutrients
B. Micro nutrients
A. Macro or Major Nutrients
-They are the nutrients utilized by the plants in relatively large amounts
(quantity) for their growth and development.
Eg; C, H. O. N, P, K, Ca, Mg and S (C, H and O are abundantly present in
the atmosphere and need not be applied through fertilizers).
1. Structure Nutrients
2. Primary Nutrients
3. Secondary Nutrients
1. Structure Nutrients:
Functions:
- They play a dominant role in the process of photosynthesis and respiration
in plants.
- They are involved in the formation of simple as well as complex organic
compounds like carbohydrates, starch proteins etc.
- Maintaining the structure of the plant cells.
- They provide ‘energy’ required for the growth and development of plant by oxidative break down of carbohydrates, proteins and fats during their
cellular respiration
2. Primary nutrients
-Primary nutrient are those nutrients required relatively in large quantities by the
plants for their growth and development. These are also designated as ‘fertilizer
elements’ because, deficiency of these elements is corrected by application
through fertilizers.
Eg: N, P and K.
1. Nitrogen (N)
Function:
- The Nitrogen is mainly involved in Photosynthesis of plants,
constituent of chlorophyll.
- It forms essential constituent of proteins, nucleotides phosphatides, alkaloids, enzymes,
hormones, vitamins etc.,
- It promotes better Vegetative growth and adequate supply of nitrogen
promotes rapid early growth and imparts dark green color to plants.
-Improves quality and succulence of leafy vegetables and fodder crops.
- It stimulates the formation of fruit buds; increases fruit set, and improve
quality of fruits.
- It governs the better utilization of Potassium, Phosphorus & other elements.
Deficiency symptoms :
Nitrogen is a highly mobile element in plants and so deficiency is exhibited in
older/ bottom leaves. The striking deficiency symptoms are
- Yellowing of older leaves due to inhibition of chloroplasts and chlorophyll
synthesis. As the deficiency of Nitrogen becomes severe “Chlorosis” of
leaves is observed.
- Plants become dwarfed or stunted growth.
- Tends to advance the time of flower bud formation and reduce yield.
2. Phosphorus (P):
Functions
- Involved in energy storage and transfer. Also carry various metabolic
processes in plants.
- Involved in cell division and development of meristematic tissue and thus it
improves better vegetative growth of plants.
- Important for root development and stimulates root growth.
- Helps in primordial development, flowering, seed formation, ripening of
fruits, germination of seeds and also early maturity of crops.
- It is essential for formation of starch, proteins, nucleic acids, photosynthesis,
nitrogen-metabolism, carbohydrate metabolism, glycolysis, respiration and
fatty acid synthesis.
Deficiency symptoms
- Stunted and slow growth of plants due to its effects on cell division andmeristematic tissue development.
- Leaves are small and defoliation starts from the older leaves and premature
leaf fall.
- Purplish discoloration of foliage due to anthocyanin pigment. Plants develop
dead necrotic areas on the leaves, petioles or fruits.
- Slender and woody stem with under developed roots are characteristics
symptoms.
- Delay in flowering and ripening of fruits, inferior quality, shedding of
blossom, inflorescence becomes small and premature fruit falling.
- Inhibit the sugar synthesis or abnormally high sugar levels in plant.
-
3. Potassium (K):
Functions
- Potassium is responsible for osmoregulation and controls cell turger
pressure.
- It has an important role in pH stabilization, enzyme activation, protein
synthesis, stomata movement (closing and opening), cell extension and
photosynthesis.
- Impart drought/heat/frost resistance to plants as it regulates transpiration and
water conditions in the plant cell. It improves water use efficiency
- Impart pest and disease resistance to plants
- Required for ATP synthesis and better N use efficiency by favoring theprotein formation.
- Plants become strong and stiff; thus it reduces lodging of plants.
- Essential in the formation and transfer of starch and sugars especially in
potato, sweet potato, turnip, banana, tapioca.
Deficiency symptoms
- Weakening of stem and lodging of crops and easy susceptibility to pest and
diseases.
- Scorching of leaves and burning appearance of leaf margins and tip
- Poor keeping quality of fruits. The quality of fruits and vegetables
decreases.
- Marginal necrosis and burning of leaf tips.
- Stunted growth, shortening of internodes.
- It causes great disturbance in the water economy of plants and more water is
lost per unit dry matter.
- Poor sprouting of vines.
- Severe attack of the grapes with Botrytis cinerea due to K deficiency.
- small tubers in potato due to low sugar occumulation.
5.Secondary nutrients
-Secondary nutrients are those nutrients which are required by plants in moderate
amounts. They are called secondary because they are unknowingly supplied
through fertilizers and other amendments. However their role in nutrition is not
secondary but they are given secondary importance in its supply and management.
Eg: Ca, Mg and S
1. Calcium (Ca)
Functions
- It is a constituent of the cell wall and promotes early root development.
- It is required for cell divisions and chromosome stability, cell wall
construction, cell elongation of the shoot and root.
- Stabilizing the pectin of the middle lamella in the cell wall by formingcalcium pectate. Thus, Ca brings resistance against diseases.
- Effect on fruit quality and increases in the firmness of the fruit.
- Indirectly influences many enzyme systems and maintain cation- anion
balance (by acting as a counter ion).
Deficiency symptoms
- Deficiency is first observed on the young leaves and growing tips (immobile
in plants).
- Leaves become small, distorted, cup shaped, crinkled and malformation of
leaves (It resembles boron deficiencies)
- Terminal buds may deteriorate and die in fruits trees. Root growth is
Impaired.
- Destruction of cell well structure results in disturbance of nuclear and cell
division.
- Fruit quality is reduced, loss of fruit fleshy, sometimes rotting of fruits and
susceptible to fungal disease.
- Blossom end rot on a tomato, soft nose in mango, Jonathan spot in apple,
empty peanut shell, black heart of celery.
2. Magnesium (Mg)
Functions
- Very much essential for photosynthesis.
- It is involved in the regulation of cellular pH, cation-anion balance and
turgur regulation of cells.
- Necessary for protein synthesis.
- Activator of enzymes in carbohydrate and ATP metabolism.
- Essential for the formation of oils and fats
- It is required for stabilization of cell membranes
Deficiency symptoms
- Interveinalchlorosis of lower leaves and in extreme cases becomes necrotic.
- Leaves remain in small and brittle even in final stages.
- Twigs may become weak and premature dropping of leaves results in heavy
loss of fruit crops.
- Inhibits nitrate reduction and the production of photo hormones.
- Stalk necrosis or stem ‘Die back’ in a Vine plant.
4. Sulphur (S):
Functions
- Required for synthesis of the S-containing amino acids like cystine, cysteine
and methionine, which are important for protein synthesis.
- Role in photosynthesis by involving in structural formation of chlorophyll in
leaves.
- It is a constituent of proteins and volatile compounds responsible for the characteristic taste & smell of plants in the mustard and onion families.
- It enhances oil synthesis in crops.
Deficiency symptoms
- Pale yellow or light green leaves in younger leaves (Deficiencies resemble
those of nitrogen)
- Stalks are short and slender, growth is retarded.
- Fruits often do not mature fully and remain light green in colour.
- In Brassica species, leaves shows cupping and curling, reduction in oilcontent of oilseed crops.
- Cell division is retarded fruit development is suppressed.
- Disrupts N metabolism, reduces protein quality and induces starch
(carbohydrate) accumulation.
B. Micro Nutrients:
-The nutrients which are required by plants in relatively smaller quantities for their
growth and development, but these are equally important and essential to plants as
macronutrients. They are also called as trace/rare/nano elements. These include
Fe, Mn, Zn, Cu, B, Mo, Cl and Ni.
1. Iron (Fe)
Functions
- Involved in biosynthesis of chlorophyll and in the synthesis of chloroplast
proteins
- Activates several enzymes involved in respiration.
- It brings about oxidation-reduction reactions in the plant.
- It regulates respiration, photosynthesis, reduction of nitrates and sulphates.
- Required for heme protein formation in legumes
Deficiency symptoms:
- Interveinalchlorosis of younger leaves and generally called as “iron
chlorosis” or lime induced chlorosis. On severe deficiency leaves become
“Pale white”.
- Reddish-brown necrotic spots along the leaf margins of young shoots in tree
crops.
- In Brassica necrotic terminal buds at early seedling stage.
Functions
- Involved in oxidation-reduction reactions and electron transport in photosystem II
- It is directly or indirectly involved in chloroplast formation and their
multiplication.
- It activates large number of enzymes and acts as a co-factor and catalyses
most of the enzymes
- It helps in movement of Iron.
- Acceleration of germination and maturity.
2. Manganese (Mn)
Functions
- Involved in oxidation-reduction reactions and electron transport inphotosystem II-
- It is directly or indirectly involved in chloroplast formation and their multiplication.
- It activates large number of enzymes and acts as a co-factor and catalyses most of the enzymes
- It helps in movement of Iron.
- Acceleration of germination and maturity.
Deficiency symptoms
- Interveinalchlorosis on old leaves similar to iron chlorosis.
- Speckled yellow of sugarbeet-leaves develop interveinal yellowish green
chlorotic mottling and leaf margins role upwards.
- Depresses inflorescence and fructification and results in stunted leaf and root development.
- Crinckleleaf of cotton, grey speak of oats.
3. Copper (Cu)
Functions
- It acts as electron carriers in enzymes which bring about oxidation-reduction
reaction in plants.
- Helps in utilization of iron in chlorophyll synthesis.
- Influence on cell wall permeability and nitrate reduction.
- Play a role in the biosynthesis & activity of ethylene in ripening fruit.
- Promote the formation of vitamin-A in plants.
- Influence on pollen formation & fertilization.
Deficiency symptom
- Narrow, twisted leaves and pale white tips. Interveinalchlorotic, mottling of
leaves.
- In fruit trees “die-back” (terminal bud wither and die) is most common.
- It affects fruit formation much more than vegetative growth.
- The critical stage of Cu deficiency induces pollen sterility in
microsporogenesis.
- Reduced fruit set and number of flowers.
- Poor pigmentation in fruits
4. Boron (B)
Function
- Essential for cell division in the meristematic tissues.
- Involved in proper pollination, pollen formation, pollen tube growth/
flowering and fruit or seed set.
- Important role in the fertilizing process of plants and during blossom period
its requirement is high.
- It influences carbohydrates and N-metabolism.
- Translocation of sugars through cellular membranes and prevents the
polymerization of sugars.
- It enhances rooting of cutting through oxidation process.
- It has role in hormone movement and action.
- It gives resistance for pest and disease infection, e.g.: virus, fungi & insects.
- Role in water relations i.e., prevents hydration of root tips & thus
strengthens the plant roots
- Acts as a regulator of potassium/calcium ratio in the plant. Solubility &
mobility of Ca increases.
Deficiencies symptoms
- Young leaves may be deformed, appear like a “rosette”, cracking and cork
formation in stems, stalks and fruits, thickening of stems and leaves,
reduced buds, flowers and seed production.
- Premature seed or fruit drop.
- ‘Hen and Chicken disease’ in grapes bunches i.e. fruits of vine with small &
long berries.
- Deformed fruits of papaya tree.
- Vine plant with thickened internodes. Poor fructification and development
of the berries. In mango, leaves become pale green distorted & brittle
leaves.
- Browning or hollow stem of cauliflower.
- Heart rot disease’ in fruits of the sweet melon (Cucumismelo), sugar beet &
marigold.
- Interruption in cell wall formation and differentiation and then necrosis.
- Flowers wilt, die and persist on the tree. This phenomenon is called
“BlossomBlast”.
- Tissue break down and preventing sugar and starch accumulation in the
leaves.
- Excessive formation and accumulation of phenolics.
- Bitter orange fruits with thickened peels or rinds & blackish discoloration.
- Black heart in root crops, dead heart in cauliflower, wheat sterility.
5. Molybdenum (Mo)
Functions
- Essential role in iron absorption and translocation in plants, protein
synthesis and N- Fixation in legumes.
- Brings oxidation and reduction reactions especially in the reduction of NO3
to NH4.
- It acts as a bridge or link in transferring electrons.
- Role in phosphate system and ascorbic acid synthesis.
Deficiency symptoms
- Reddish or purplish discoloration of leaves, chlorosis and marginal necrosis
of leaves.
- Marginal scorching and rolling or cupping of leaves, “Yellow spot” disease
of citrus and “Whiptail” in cauliflower is commonly associated.
- NO3 accumulation in plants thus inhibits the utilization of N for protein
synthesis.
- Mo Deficiency (Bright yellow mottling between veins; leaves wither, curl
and margins collapse; leaves distorted and narrow; older leaves affecter
first.)
6. Chlorine (Cl)
Functions:
- Involved in the evolution of “Oxygen” by chloroplasts in photo system-II.
- Associated with turgor production in the guard cells by the osmotic pressure
exerted by K+
ions
- Role in stomata regulation (opening & closing).
- Water splitting in photo system-II.
- Act as a bridging ligand for stabilization of the oxidized state of Mn.
Deficiency symptom
- Chlorosis and burning of tips and margin of leaves. In tomato, leaves
become chlorotic and later bronzed.
- Over wilting effect and leaf fall, yielding ability decreases.
Chloride toxicity on many crops- Bronze or yellow colors of leaves with
brown or scorched leaf margins.
7. Zinc (Zn)
Zinc is having limited mobility in plants and immobile in soil and plant absorb as
Zn2+ form.
Functions
- Zn is a constituent of several enzymes systems which regulate various
metabolic reactions in the plant.
- Influences the formation of some growth hormones in the plant like IAA,
and Auxin.
- Helpful in reproduction of certain plants.
- Role in photosynthesis and involved in chlorophyll synthesis, protein
synthesis.
- Involved in alcohol dehydrogenase activity in fruit trees.
Deficiency symptoms
- Chlorotic and Brown rusty spots on leaves.
- Lower Auxin level.
- Drastic decrease in leaf area and leaf deformation (Rosetting), stunted
growth (shortage of internodes).
- Under severe deficiency the shoot apices die (dieback) and diffusive or
mottled leaf
- The rate of protein synthesis is drastically reduced and amino acids and
amides accumulate.
- Khaira disease in rice.
8. Nickel (Ni)
Unit 2
Source of nutrients
Organic source:
• Organic fertilizers are natural materials of either plant
or animal origin, including livestock manure, green
manures, crop residues, household waste, compost,
and woodland litter.
• Organic fertilizers include both plant and animal biproducts.
• They are slow acting.
• Organic nitrogen fertilizers include oil cakes, fish
manure, dried blood from slaughter houses etc.,
whereas organic phosphorus fertilizers are from bone
meal and organic potassium from cattle dung ash,
wood ash, leaf mould, tobacco stems and water
hyacinth.
Advantages
• Organic fertilizers mobilize existing soil
nutrients.
• They increase physical and biological
nutrient storage mechanisms in soils,
mitigating risks of over-fertilization.
• They helps to release nutrients at a slower
and consistent rate.
• They help to retain soil moisture, reducing
the stress due to temporary moisture stress.
• They improve the soil structure.
• They help to prevent top soil erosion.
Disadvantages
• It require large amounts to be applied to have
desirable effects.
• Transporting large amount of fertilizer incurs
higher costs, especially with slurry and manure.
• The composition of organic fertilizers tends to
be more complex and variable than a
standardized inorganic product.
• More labor is needed to compost organic
fertilizer, increasing labor costs.
• Unavailability of seed for green manures is one
of the major limitations.
• Green manures must occupy land at a time
when other food crops could be grown.
Inorganic source
• Inorganic (or mineral) fertilizers are fertilizers
mined from mineral deposits with little
processing (e.g., lime, potash, or phosphate
rock), or industrially manufactured through
chemical processes (e.g., urea).
• Inorganic fertilizers vary in appearance
depending on the process of manufacture.
• The particles can be of many different sizes
and shapes (crystals, pellets, granules, or
dust).
• Inorganic fertilizer could be classified into
three based on the nutrient composition as
follows:
Straight fertilizers: These are fertilizers which
contain and supply one or single nutrient
element only. They could be nitrogenous,
phosphatic or potassic fertilizers supplying
nitrogen, phosphorus or potassium, respectively.
• Complex/Compound fertilizers: These are
fertilizers which contain two or more nutrient
elements usually combined in a homogeneous
mixture by chemical interaction. Complex NPK
fertilizers have the advantage of having each
nutrient in each granule.
Fertilizer blends or mixed fertilizers:
These are fertilizers formed by physically
blending mineral fertilizers to obtain
desired nutrient ratios. Two or more of the
separate fertilizer carriers or straight
fertilizers are mixed to obtain the desired
nutrient ratios. Examples are NPK 15-
15-15, NPK 20-10-10 etc.
Advantages and Disadvantages of Inorganic
Fertilizers
Advantage:
-Works immediate
-contain all necessary nutrients that are ready for use.
-affordable
-convenient to use and easy to apply
Disadvantage:
-leeching occurs
-may burn
-some are not affordable
-accmulation of toxic waste
Organic manure
• Organic manure are bulky in nature and supply
nutrients in small quantities and organic matter in
large quantities.
importance and scope:
• Organic manure provides all the nutrients that are
required by plants but in limited quantities.
• It helps in maintaining C:N rati