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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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