2. CONTENTS
❑.METHODS TO STUDY THE MINERAL
REQ. OF PLANTS
❑DIAGRAM OF TYPICAL SET-UP OF
NUTRIENT CULTURE OF PLANTS
❑CRITERIA FOR ESSENTIALITY
❑MACRO AND MICRO NUTRIENTS
❑ROLE OF MICRONUTRIENTS
❑THE NITROGEN CYCLE
3. METHODS TO STUDY THE MINERAL
REQUIREMENTS OF PLANTS
⮚ HYDROPONICS : technique of growing plants in a
nutrient solution.
⮚ Demonstrated by JULIAN VON SACHS (1860).
⮚ Culture of plants in soil-free mineral soln. requires purified
H2O and mineral nutrient salts.
⮚ After series of exps. ,
▪ Essential elements identified
▪ Deficiency symptoms discovered
▪ Commercial production of vegs like tomato , lettuce and seedless
cucumber.
4. ⮚ DIAGRAM FOR TYPICAL SET-UP FOR
NUTRIENT SOLN. CULTURE.
Aerating
tube
Cotton
Nutrient
soln.
Funnel for
adding
water and
nutrients
5. CRITERIA FOR ESSENTIALITY of an element
The element must necessarily support
normal growth and reproduction . if absent,
the plant do not complete life cycle or set seeds.
The deficiency of one element cannot be
met by supplying another element.
The element must be directly involved in
the metabolism of the plant.
Based on this criteria along with
quantitative req. and diverse
funct., essential elements and are
classified into,
•Quantitative requirements.
• MACRONUTRIENTS
• MICRONUTRIENTS
•Diverse functions
❑ 4 categories
6. MACRO AND MICRO NUTRIENTS
❖MACRONUTRIENTS
▪ Present in plant tissues in large amts.= >10mmole Kg-1
of dry matter.
•From CO2 and H2O
•Carbon
•Hydrogen
•Oxygen
•From soil
•Nitrogen
•Phosphorus
•Sulphur
•Potassium
•Calcium
•magnesium
7. ❖ MICRONUTRIENTS
◼ Also known as trace elements.
◼ Needed in small amts.=<10mmole Kg-1 of dry matter.
▪ includes ,
iron
mangan
ese
copper nickel
molybde
num
zinc
chlorine boron
❑In addition to these 17 elements ,some beneficial elements like
•Sodium
•Silicon
•Selenium
•Cobalt - are required by higher plants.
❖Based on diverse functions , elements are
I. Components of biomolecules . E.g. : carbon , hydrogen
II. Components of energy-related chemical compounds . E.g. : phosphorus in
ATP.
III. Activators or inhibitors of enzymes.Eg:Mg2+ is actvr. of RUBISCO & PEPcase.
IV. Alterers of osmotic potential of cells.E.g: K+ in opening and closing stomata.
8. ROLE OF MACRO-MICRO NUTRIENTS
ESSENTIAL
NUTRIENTS
FORM OF
ABSORPTION
FUNCTION DEFICIENCY
SYMPTOMS
1. NITROGEN NO3
-,NO2
-
,NH4
+
•Needed by
▪Meristematic tissues
▪Metabolically active
cells
•Constituent of
▪Proteins
▪Nucleic acids
▪Vitamins
▪hormones
oChlorosis1
oInhibition of
cell division.
oDelayed
flowering
2.PHOSPHORUS H2PO4
- ,HPO4
2- •Constituent of
▪ Cell membranes
▪ some proteins
▪All nucleic acids
▪Nucleotides
9. ESSENTIAL
NUTRIENTS
FORM OF
ABSORPTION
FUNCTION DEFICIENCY
SYMPTOMS
•Required for
▪Phosphorylation
reactions
3.POTASSIUM K+ •Required in
▪Meristematic tissues
▪Buds , leaves
▪Root tips
•Helps in
▪anion-cation balance
▪Protein synthesis
▪Open-closure of
stomata
▪Activation of enzymes
▪Turgidity of cells
oChlorosis
oNecrosis2
oInhibition
of cell
division.
4.CALCIUM Ca2+ •Required for
▪Meristematic &
differentiating tissues
•Formation of
▪Cell wall
▪Mitotic sphindle
oNecrosis
oBrown
spots
surrounded
by chlorotic
veins3.
10. ESSENTIAL
NUTRIENTS
FORM OF
ABSORPTION
FUNCTION DEFICIENCY
SYMPTOMS
5.MAGNESIUM Mg2+ •Required for
▪Photosynthesis
▪Activation of enzymes
for respiration
▪Synthesis of DNA &
RNA
•Maintain ribosome
structure.
•Constituent of ring
structure of chlorophyll.
oChlorosis
oNecrosis
oBrown
spots
surrounded
by chlorotic
veins.
6.SULPHUR SO4
2- •Present in 2 amino acids
▪Cysteine
▪Methionine
•Constituent of
▪Vitamins
▪ferredoxin
oChlorosis
oInhibition
of cell
division.
oDelayed
flowering
7.IRON Fe3+ •Transfer of e- like
ferredoxin & cytochromes.
•Activates catalase enzyme.
•Essential for formation of
chlorophyll.
oChlorosis
oBrown spots
surrounded
by chlorotic
veins.
11. ESSENTIAL
NUTRIENTS
FORM OF
ABSORPTION
FUNCTION DEFICIENCY
SYMPTOMS
8.MANGANESE Mn2+ •Activates enzymes during
▪Photosynthesis
▪Respiration
▪N metabolism
•Splitting of water to
release O2 during
photosynthesis.
oChlorosis
9.ZINC Zn2+ •Activates various enzymes
▪Carboxylases
•Synthesis of auxin.
oChlorosis
10.COPPER Cu2+ •For overall metabolism
•Associated with enzymes
in redox reactions.
oNecrosis
11.BORON BO3
3-,B4O7
2- •Uptake and utilization of
Ca2+
•Membrane functioning
•Pollen germination
•Cell elongation
•Carbohydrate translocation
12. ESSENTIAL
NUTRIENTS
FORM OF
ABSORPTION
FUNCTION DEFICIENCY
SYMPTOMS
12.MOLYBDENUM MoO2
2- •Component of
▪Nitrogenase
▪Nitrate reductase
oChlorosis
oDelayed
flowering
13.CHLORINE Cl- •Determines solute
concentration
•Anion-cation balance
•O2 evolution by water
splitting.
N-metabolism
1. CHLOROSIS : Loss of chlorophyll leading to yellowing in leaves.
2. NECROSIS : Death of tissues , particularly in leaves.
❑ TOXICITY OF ELEMENTS
3. Brown spots surrounded by chlorotic veins is due manganese
toxicity.
• Any mineral ion concentration in tissues that reduces the dry
weight of tissues by 10% is considered toxic.
13. THE NITROGEN CYCLE
SHOWING RELATIONSHIP BTW THE 3 MAIN N2 POOLS –ATM. SOIL, AND
BIOMASS
Atmospheric N2
Biological
N2 fixation
Industrial
N2
fixation
Electrical
N2 fixation
Denitrification
Animal
biomass
Decaying
biomass
Plant
biomass
NO2
- NO3
-
NH3
SOIL ‘N’ POOL
(Ammonification) (Uptake)
