by Dilip Kumar Chandra PGT Biotechnology JNV Raipur CG

1. By Dilip Kumar Chandra

2.  Plants are:
 Capable of making all necessary organic compounds
from inorganic compounds and elements in the
environment (autotrophic)
 Supplied with all the carbon, hydrogen, and oxygen
they could ever need (CO2, H2O)
 Required to obtain all other elements from the soil
so in a sense plants act as soil miners.

3.  The study of how plants obtain, distribute,
metabolize, and utilize mineral nutrients.
 “Mineral”: An inorganic element
 Acquired mostly in the form of inorganic ions from the
soil
 “Nutrient”: A substance needed to survive or
necessary for the synthesis of organic compounds

4.  Amount required or present in plant tissue
 Metabolic need for the mineral nutrient
 Biochemical function(s) for the mineral
nutrient
 Mobility within the plant

7. Mineral nutrient deficiencies occur when the
concentration of a nutrient decreases below
this typical range
 Deficiencies of specific nutrients lead to
specific visual, often characteristic, symptoms
reflective of the role of that nutrient in plant
metabolism

9.  The location where a
deficiency reflects the
mobility of a nutrient
 Nutrients are
redistributed in the
phloem
 Old leaves = mobile
 Young = immobile

10. Essential: Universal for all plants
 – Absence prevents completion of life cycle
 – Absence leads to deficiency
 – Required for some aspect of mineral nutrition
• Beneficial: Often limited to a few species
 – Stimulates growth and development
 – May be required in some species
 – Examples: Na, Si, Se

11.  There are four basic groups:
 Group one:
 Forms the organic components of plants
 Plants assimilate these nutrients via biochemical
reactions involving oxidation and reduction
 Group two:
 Energy storage reactions or maintaining structural
integrity
 Present in plant tissue as phosphate, borate or silicate
esters
 The elemental is bound to OH group of an
organic molecule

13.  Group three:
 Present in plant tissue as either free ions
or ions bound to substrates such as the
pectin component of the plant cell wall
 Of particular importance are their roles as
 Enzyme cofactors
 In the regulation of osmotic potentials

15.  Group four:
 This last group has important roles in reactions
involving electron transfer.
 Some also involved in the formation of plant
growth hormones – Zinc
 The light reaction of photosynthesis - Copper

17. Uptake through the leaves
• Artificial: called foliar application.
Used to apply iron, copper and
manganese.
• Associations with mycorrhizal fungi
• Fungi help with root absorption
• Uptake by the roots

18.  pH affects the growth of plant roots
and soil microbes
 Root growth favors a pH of 5.5 to
6.5
 Acidic conditions weathers rock
and releases potassium,
magnesium, calcium, and
manganese.
 The decomposition of organic
material lowers soil pH.
 Rainfall leaches ions through soil
to form alkaline conditions

19.  Negatively charged soil particles
affect the absorption of mineral
nutrients
 Cation exchange occurs on the
surface of the soil particle
 Cations (+ve charged ions) bind
to soil as it is –ve charded
 If potassium binds to the soil it
can displace calcium from the soil
particle and make it available for
uptake by the root

20.  Meristematic zone
 Cells divide both in direction of
root base to form cells that will
become the functional root and
in the direction of the root apex
to form the root cap
 Elongation zone
 Cells elongate rapidly, undergo
final round of divisions to form
the endodermis. Some cells
thicken to form casparian strip
 Maturation zone
 Fully formed root with xylem
and phloem – root hairs first
appear here

21.  Calcium
 Apical region
 Iron
 Apical region (barley)
 Or entire root (corn)
 Potassium, nitrate, ammonium,
and phosphate
 All locations of root surface
 In corn, elongation zone has max K
accumulation and nitrate absorption
 In corn and rice, root apex absorbs
ammonium faster than the
elongation zone does
 In several species, root hairs are the
most active phosphate absorbers

22.  Tissues with greatest need for nutrients
 Cell elongation requires Potassium, nitrate, and chlorine to
increase osmotic pressure within the wall
 Ammonium is a good nitrogen source for cell division in
meristem
 Apex grows into fresh soil and finds fresh supplies of nutrients
 Nutrients are carried via bulk flow with water, and
water enters near tips
 Maintain concentration gradients for mineral
nutrient transport and uptake

23.  Formation of a nutrient
depletion zone in the region
of the soil near the plant root
 Forms when rate of nutrient
uptake exceeds rate of
replacement in soil by
diffusion in the water
column
 Root associations with
Mycorrhizal fungi help
the plant overcome this
problem

24.  Not unusual
 83% of dicots, 79% of monocots
and all gymnosperms
 Ectotrophic Mycorrhizal fungi
 Form a thick sheath around root.
Some mycelium penetrates the
cortex cells of the root
 Root cortex cells are not penetrated,
surrounded by a zone of hyphae
called Hartig net
 The capacity of the root system to
absorb nutrients improved by this
association – the fungal hyphae are
finer than root hairs and can reach
beyond nutrient-depleted zones in
the soil near the root

25. • Vesicular arbuscular
mycorrhizal fungi
– Hyphae grow in dense
arrangement , both within the root
itself and extending out from the
root into the soil
– After entering root, either by root
hair or through epidermis hyphae
move through regions between cells
and penetrate individual cortex
cells.
– Within cells form oval structures –
vesicles – and branched structures –
arbuscules (site of nutrient transfer)
– P, Cu, & Zn absorption improved by
hyphae reaching beyond the nutrient-
depleted zones in the soil near the root

26.  Ectotrophic Mycorrhizal
 Occurs by simple diffusion from the hyphae in the
hartig net to the root cells
 Vesicular arbuscular mycorrhizal fungi
 Occurs by simple diffusion from the arbuscules to
the root cells
 Also, as arbuscules are degenerating as new ones
are forming, the nutrients may be released
directly into the host cell

27.  Increase plant growth and yield
 Increase plant nutritional quality and
density
 Increase removal of soil contaminants (as in
phytoremediation)