Mineral nutrition in plants

Soil fertility and nutrient management

1. Mineral Nutrition
SOLE OF INFINITE LIFE
Dr. B.R. Jagadeesh
Associate Professor of Soil Science
College of Agriculture
Hanumanamatti, Haveri

2. Mineral Nutrition in plants
•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 mines.

3. Mineral Nutrition in plants

•“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. Classification of mineral nutrients
•Amount required or present in plant tissue
•Metabolic need for the mineral nutrient
•Biochemical function(s) for the mineral
nutrient
•Mobility within the plant

5. Mineral macronutrients

6. Mineral micronutrients

7. Nutrient deficiencies
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

8. Nutrient Deficiency v/s. Sufficiency

9. Patterns of deficiency
•The location where a
deficiency reflects the
mobility of a nutrient

•Nutrients are
redistributed in the
phloem

•Old leaves = mobile
•Young = immobile

10. Essentiality of mineral nutrients
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. Essentiality of mineral nutrients
•There are four basic groups:
•Group I:
–Forms the organic components of plants
–Plants assimilate these nutrients via biochemical
reactions involving oxidation and reduction
•Group II:
–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

12. Biochemical functions of mineral
nutrients

13. Essentiality of mineral nutrients
•Group III:
–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

14. Biochemical functions of mineral
nutrients

15. Essentiality of mineral nutrients
•Group IV:
–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

16. Biochemical functions of mineral
nutrients

17. Uptake of mineral nutrients
by plants?
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. The soil affects nutrient absorption
•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. The soil affects nutrient absorption
•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
Plant roots – the primary route
for mineral nutrient acquisition

21. Root absorbs different mineral ions in
different areas
•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. Why should root tips be the primary site
of nutrient uptake?
•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. Root uptake soon depletes nutrients
near the roots
•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. Mycorrhizal associations
•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. Mycorrhizal associations
•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. Nutrients move from fungi to root cells
•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. Manipulating mineral transport
in plants
•Increase plant growth and yield

•Increase plant nutritional quality and density

•Increase removal of soil contaminants (as in
phytoremediation)

28. Periodic table of plant mineral nutrition

29. The end