Transcript carbon leaf

NUTRITION IN PLANTS
1) Nutrients :The components of food like carbohydrates, fats,
proteins vitamins and minerals are called nutrients.
Nutrients help living organisms :i) To build their bodies.
ii) To grow.
iii) To repair the damaged parts of their bodies.
iv) To provide energy to carry out life processes.
2) Nutrition :The mode of taking food by an organism and its
utilization in the body is called nutrition.
3) Modes of nutrition :- There are two main modes of
nutrition in living organisms. They are autotrophic nutrition
and heterotrophic nutrition.
i) Autotrophic nutrition :- is nutrition in which organisms
can prepare their own food.
Organisms which can prepare their own food are called
autotrophs.
ii) Heterotrophic nutrition :- is nutrition in which organisms
get their food directly or indirectly from plants.
Organisms which get their food directly or indirectly from
plants are called heterotrophs.
4)Photosynthesis - Food making process in plants :-
Photosynthesis is the process by which plants prepare
their on food by using sunlight, water, carbon dioxide and
chlorophyll.
Photosynthesis take place in the leaves.
i) Sunlight is obtained from the sun.
ii) Water is absorbed by the roots and transported to the
leaves.
iii) Carbon dioxide is taken from the air through small
pores in the
leaves called stomata.
iv) Chlorophyll are the green pigments present in the
leaves.
Chlorophyll uses the energy from sunlight to prepare food
by using water and carbon dioxide. The food prepared is
carbohydrate which is then converted into starch. During
photosynthesis oxygen is released.
Equation of photosynthesis :Sunlight
Carbon dioxide + Water
Carbohydrate +
Oxygen
Chlorophyll
5) Synthesis of proteins :The soil has some bacteria which convert nitrogen from
the air into usable nitrogen in the soil. Farmers also add
fertilisers containig nitrogen into the soil. Plants absorb
this nitrogen from the soil along with water and other
constituents to prepare proteins and fats.
6) Other modes of nutrition in plants :i) Parasitic plants :- are plants which do not have
chlorophyll and cannot prepare their own food. They get
their food from other plants called host . Eg :- Cuscuta (
Amarbel)

ii) Insectivorous plants :- are plants which feed on
insects. Eg:- Pitcher plant. The leaf of the pitcher plant is
modified into a pitcher. The end of the pitcher has a lid
which can open and close. When an insect enters the
pitcher, the lid closes. The insect is then digested by
digestive juices inside the pitcher.

iii) Saprotrophs :- are plants which do not have
chlorophyll and cannot prepare their on food. They get
their food from dead and decaying organic matter. Eg :mushroom, bread mould etc. They produce digestive juice
on the dead and decaying organic matter and convert it
into a solution and then absorb the nutrients from the
solution.
iv) Symbiotic relationship :- Some plants live together
and share shelter and nutrients. Eg :- lichens. In lichens,
an alga and a fungus live together. The fungus provides
shelter, water and minerals to the alga. The alga provides
food to the fungus which it prepares by photosynthesis.
7) How nutrients are replenished in the soil :Plants absorb nutrients from the soil. So the nutrients in
the soil decreases. So farmers add manures and fertilisers
to the soil to increase the nutrients in the soil.
The bacterium called rhizobium which lives in the roots
of leguminous plants like grams, peas, beans etc. converts
nitrogen from the air into soluble form in the soil and
makes the soil rich in nitrogen. In return the plant
provides food and shelter to the bacteria. So they have a
symbiotic relationship.
Essential plant nutrients
Introduction
A total of only 17 elements are essential for the growth and
full development of higher green plants according to the
criteria laid down by Arnon and Stout (1939). These criteria
are:
• A deficiency of an essential nutrient makes it impossible for
the plant to complete the vegetative or reproductive stage
of its life cycle.
• Such deficiency is specific to the element in question and
can be prevented or corrected only by supplying this
element.
• The element is involved directly in the nutrition of the plant
quite apart from its possible effects in correcting some
unfavourable microbiological or chemical condition of the soil
or other culture medium.
Essential plant nutrients
Introduction
The
essentiality
of
most
micronutrients for higher plants was
established between 1922 and 1954.
The essentiality of nickel (Ni) was established in
1987 by Brown et al., although there is no
unanimity among the scientists as to whether Ni
is essential or beneficial.
However, this list may not be considered as
final and it is probable that more elements
may prove to be essential in future. The
chronology of discoveries of essential
nutrient elements is given in Table (see next
slide).
Essential plant nutrients
Chronology of discoveries of essential nutrient elements for
higher plants
Element
Year
Carbon (C)
Discoverer of
Essentiality
DeSaussure
Hydrogen (H)
DeSaussure
1804
Oxygen (O)
DeSaussure
1804
Nitrogen (N)
DeSaussure
1804
Phosphorus (P)
Ville
1860
Potassium (K)
von Sachs, Knop
1860
Sulphur (S)
von Sachs, Knop
1865
Calcium (Ca)
von Sachs, Knop
1860
Magnesium (Mg)
von Sachs, Knop
1860
1804
(Glass, 1989; Marschner, 1997)
Essential plant nutrients
Chronology of discoveries of essential nutrient elements for
higher plants
Element
Year
Iron (Fe)
Discoverer of
Essentiality
von Sachs, Knop
Manganese (Mn)
McHargue
1922
Copper (Cu)
Lipman
MacKinney
and 1931
Sommer
Lipman
and 1938
Zinc (Zn)
Molybdenum (Mo)
Boron (B)
Chlorine (Cl)
Nickel (Ni)
Arnon and Stout
Warington
Broyer et al.
1860
1926
1923
1954
1987
(Glass, 1989; Marschner, 1997)
Essential plant nutrients
Classification of essential plant nutrients
Essential plant nutrients
Frame-work nutrient elements
Carbon (C) and oxygen (O) are
obtained from the gas CO2, and
hydrogen (H) is obtained from
water (H2O).
These three elements are required
in
large
quantities
for
the
production of plant constituents
such as cellulose or starch.
Hence, many times referred as
frame-work elements.
Oxygen, carbon and hydrogen
make up 95 percent of plant
biomass, and the remaining 5
percent is made up by all other
elements.
Essential plant nutrients
Macronutrients
Macronutrients are nitrogen (N), phosphorus (P),
potassium (K), calcium (Ca), magnesium (Mg), and
sulphur (S).
The one or two letter symbol in parentheses is the
universal chemical symbol for that nutrient.
N, P, and K are often referred to as primary
nutrients and are the most common elements
found in commercial fertilizers.
Ca, Mg, and S are referred to as secondary
nutrients and are also found in fertilizers and
soil amendments.
Essential plant nutrients
Micronutrients
Micronutrients include iron (Fe), manganese
(Mn), zinc (Zn), boron (B), copper (Cu),
chloride (Cl), molybdenum (Mo), and nickel
(Ni).
Micronutrients are required in relatively
minute quantities and rarely limit plant
growth in the environment.
Note: Cobalt (Co), sodium (Na), vanadium (V) and silicon
(Si) are sometimes called as beneficial plant nutrients.
They are not required by all plants but appear to benefit
certain plants. Cobalt is required for nitrogen fixation in
legumes. Silicon is found in plant cell walls and appears to
produce tougher cells. This increases the resistance of
these plants to piercing and sucking insects and decreases
the spread of fungal diseases.
Essential plant nutrients
Typical concentrations of nutrient elements sufficient for plant
growth
Relative
Element
Symbol
mg/kg
percent
number
of atoms
Nitrogen
N
15,000
1.5
1,000,000
Potassium
K
10,000
1.0
250,000
Calcium
Ca
5,000
0.5
125,000
Magnesium
Mg
2,000
0.2
80,000
Phosphorus
P
2,000
0.2
60,000
Sulphur
S
1,000
0.1
30,000
(Epstein, 1965; Epstein and Bloom, 2005)