by Dilip Kumar Chandra PGT Biotechnology JNV Raipur CG

1. MINERAL NUTRITION IN PLANTSMINERAL NUTRITION IN PLANTS
By Dilip Kumar Chandra

2. Net flow in
whole plants

3. Some Key Concepts
• Diffusion: movement of molecules from
high to low concentration.
• Osmosis: diffusion across a semi-
permeable membrane.
• Mass or bulk flow: movement of fluid due
to pressure or gravity differences.

12. Long-distance movement of water
• Plants mostly obtain water & minerals from
soil.
• Water moves up the xylem by bulk flow.
• Movement of water depends on
transpiration pull, cohesion & adhesion of
water molecules, capillary forces, and
strong cell walls.

13. Fig. 39.12a

14. Fig. 39.12b

15. •transpirational pull
•flow from greater to lower
water concentration
•relies on cohesion &
adhesion of water
–cavitation breaks chain of
water molecules
Ascent of xylem sap

16. Figure 35.11 Water-conducting cells of xylem

17. Other mechanisms of water
transport not important.
• Diffusion (note mosses, etc.)
• Capillary forces
• Osmotic pressure (guttation)

18. Fig. 39.11

19. The availability of soil water and minerals
Long-distance transport of water from roots to leaves

20. Mineral Uptake Key Points
• Mineral movement to root by diffusion or bulk
flow or root growth.
• Uptake controlled at root endodermis.
• Uptake by either simple diffusion (no protein),
facilitated diffusion (protein channel), or active
uptake (requires energy and a protein carrier).
• Organisms concentrate minerals and most other
substances.
• Usually biggest energy expenditure of roots, cause
nutrients are being concentrated.

25. Movement of sugars
• Sugars (etc.) move from the source
– Photosynthetic leaves
– Storage organ
• To the sink
– Growing organs
– Developing storage tissue
• Through mass flow in phloem
• Pressure Flow Hypothesis

26. Phloem transport
• pressure flow
1 high sugar concentration at
“source”
2 sugar diluted with water
from xylem creating
pressure for flow
3 sugar unloaded at “sink”
where it is metabolized or
converted to starch
4 excess water flows to
xylem back to “source”
• translocation: movement
of food from “source” to
“sink(s)”
Pressure flow in a sieve tube

27. Transport Movies

28. Some “hot” areas in plant water
and nutrient research
• Improving plant water-use efficiency
• Improving salt tolerance
• Improving nutritional value of plants (e.g.,
golden rice, increasing Fe content)
• Phytoremediation

29. Life on Earth
depends on
flow of energy
from sun

31. Life processes are driven by
energy
• Plants are dynamic metabolic systems
– 1000s of reactions occur every second
• Processes can be
– energy consuming (endergonic) or
– energy releasing (exergonic) and
– catabolic (breakdown) or
– anabolic (synthesis)

32. Fig. 8.6

33. Fig. 8.7

35. The most common and important
forms of cellular energy.
• Chemical bonds (e.g., ATP, CH2O)
• Electrons (redox reactions)
• Electrochemical gradients

36. Fig. 8.14

38. Cellular respiration
• Chemical-bond energy in sugars is converted to
energy-rich compound ATP which can then be
used for other metabolic reactions

44. Fig. 9.19

45. Energy yield depends on oxygen
• Aerobic (with oxygen)
– 36 ATP molecules per glucose molecule
• Anaerobic (without oxygen)
– 2 ATP molecules per glucose molecule