1. Soil Ecologist, The Morton Arboretum
Salt stress in trees
Meghan G. Midgley
Soil Ecologist, The Morton Arboretum

2. Salt enhances water stress (in an already water-limited environment)

3. Salt enhances water stress (in an already water-limited environment)

4. Salt enhances water stress (in an already water-limited environment)

5. Salt enhances water stress (in an already water-limited environment)

6. Salt enhances water stress (in an already water-limited environment)

7. Trees get water and nutrients from soil though the processes of osmosis and transpiration
Decreasing water potential
-100 MPa
-0.8 MPa
Plants pump K+ into guard cells to open stomates
-0.3 MPa

8. Decreasing water potential
Trees get water and nutrients from soil though the processes of osmosis and transpiration
Decreasing water potential
-100 MPa
-0.8 MPa
-0.3 MPa

9. Decreasing water potential
Osmotic stress: Salt makes a bad (water) situation worse by decreasing soil water potential
Decreasing water potential
-100 MPa
-0.8 MPa
-0.7 MPa

10. Salt stress in trees Osmotic stress
Decreased osmotic potential of soil water
Desiccation of entire plant
Alternatives:
Close stomates (conserve water)
Produce solutes (decrease cellular osmotic potential)
Unable to gain carbon  decreased growth
Energy intensive  decreased growth

11. Ionic stress: Sodium interferes with plant metabolic processes
Na+
Na+
Na+
Na+

12. Na+ competes with K+ for binding sites essential to cellular functions
Plants pump K+ into guard cells to open stomates (photosynthesis)
K+ binds tRNA to ribosomes (protein synthesis)

13. Na+ interferes with Mg2+ uptake (chlorophyll)
Ionic stress can lead to leaf burn

14. Salt stress in trees Osmotic stress
Decreased osmotic potential of soil water
Ionic stress
Increased salt ion concentration in cells
Desiccation of entire plant
Too much Na+ relative to K+
Deceases stomatal movements
Deceases protein synthesis
Too much Na+ relative to Mg2+
Decreases chlorophyll production/photosynthesis
Alternatives:
Alternatives:
Close stomates (conserve water)
Produce solutes (decrease cellular osmotic potential)
Salt ion exclusion from the cells
Salt ion compartmentalization (accumulation in vacuoles)
Unable to gain carbon  decreased growth
Energy intensive  decreased growth

15. Salt stress in trees Osmotic stress
Decreased osmotic potential of soil water
Ionic stress
Increased salt ion concentration in cells

16. Salt stress in trees Osmotic stress
Decreased osmotic potential of soil water
Ionic stress
Increased salt ion concentration in cells
Desiccation of entire plant
Too much Na+ relative to K+
Deceases stomatal movements
Deceases protein synthesis
Too much Na+ relative to Mg2+
Decreases chlorophyll production/photosynthesis
Alternatives:
Alternatives:
Close stomates (conserve water)
Produce solutes (decrease cellular osmotic potential)
Salt ion exclusion from the cells
Salt ion compartmentalization (accumulation in vacuoles)
Unable to gain carbon  decreased growth
Energy intensive  decreased growth