Plant nutrition : plant nutrition is the study of the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply.

1. Plant nutrition
Dr Jahangeer Ahmad Baba

10. Plant nutrition : plant nutrition is the study of the
chemical elements and compounds necessary for
plant growth, plant metabolism and their external
supply.
Criteria for Essentiality: (Arnon and Stout 1939)
➢ The element must be absolutely necessary for supporting
normal growth and reproduction. In the absence of the element the
plants do not complete their life cycle or set the seeds.
➢ The requirement of the element must be specific and not
replaceable by another element. In other words, deficiency of any
one element cannot be met by supplying some other element.
➢ The element must be directly involved in the metabolism of the
plant.

11. Minerals
CO2
O2
H O2

12. Complete solution containing
all minerals (control)
Solution lacking
potassium (experimental)
– Macronutrients, such as
carbon and nitrogen
• Are needed in large
amounts, mostly to
build organic
molecules
– Micronutrients, including
iron and zinc
• Are needed in small
amounts, act mainly
as cofactors of
enzymes

13. Name Chemical Relative Function in plant
symbol % in plant
to N
Primary macronutrients
Nitrogen N 100 Proteins, amino acids
Phosphorus P 6 Nucleic acids, ATP
Potassium K 25 Catalyst, ion transport
Secondary macronutrients
Calcium Ca 12.5 Cell wall component
Magnesium Mg 8 Part of chlorophyll
Sulfur S 3 Amino acids
Iron Fe 0.2 Chlorophyll synthesis
Micronutrients
Copper Cu 0.01 Component of enzymes
Manganese Mn 0.1 Activates enzymes
Zinc Zn 0.03 Activates enzymes
Boron B 0.2 Cell wall component
Molybdenum Mo 0.0001 Involved in N fixation
Chlorine Cl 0.3 Photosynthesis reactions

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Plant root hairs
– Are closely associated with the soil
Soil particle surrounded
by film of water
Root hair
Water
Air space

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Cations, positively charged ions
– Adhere to soil particles
• In cation exchange, root hairs release H+ ions
– Which displace cations from the soil
particles, allowing
the root hairs to
absorb them Clay
particle
Root hair
H+
K+
K+
K+
K+
K+
K+
K+
K+

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Anions, negatively charged ions
– Are readily available to plants because
they are not bound to soil particles
– Tend to drain out of the soil rapidly

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Transpiration pulls water
up xylem vessels
• Transpiration can
move xylem sap
– Which
consists of
water and
dissolved
organic
nutrients, to
the top of the
tallest
tree Figure 32.3
Root hair
Flowofwater
Soil particle
Water
Water uptake from soil
Adhesion
Cell
wall
Cohesion,
by hydrogen
bonding
Xylem
cells
Cohesion and
adhesion in the xylem
Xylem sap
Mesophyll cells
Air space within leaf
Stoma
Outside air
Transpiration
Water
molecule

24. Soil pH
Greatest nutrient availability in 5.5-6.5 range