ATMOSPHERE-PLANT-SOIL CONTINUUM Flashcards
water movement through the leaf
1
stomata open
water vapor diffuses from internal air space
net loss of wv causes air-water interface to recede
establishment of w gradient beings when the air-water interface touches outer microfibrils
Generates tension
Time dependent buildup of surface tension
Water is pulled towards air-water-interface
Apoplasmic pathway
water potential
Stomata
Low water potential, high surface tension, high evaporation
Xylem
high water potential, low surface tension, low evaporation
Apoplasmic pathway
water moves through the intercellular spaces with no entry into cells
Symplasmic pathway
water moves through the cells vis plasmodesmata
transcellular pathway
water moves across the plasma membrane
tracheid
primitive water-conducting elements
present in angiosperms and gymnosperms
long thing cells
pit pair
embolisms are confined to individual tracheid cells
Vessel
advanced water-conducting elements
stacking of vessel elements
only in angiosperms
one-vessel-n vessel element
pit pair
perforation plate
embolism expands to fill entire vessel
xylem is vulnerable to
cavitation
Embolized xylem vessel
no longer hold water
decrease xylem hydraulic conductance
pit membranes
permit water flow and limit embolism spread
impermeable torus, permeable margo
cohesion theory
the tensile strength of water is high enough to allow water to be pulled through the treachery elements
root architecture
affected by water flow into roots
increase of root production and its length
lateral root formation
enhanced lateral root growth
root pressure
In the early morning before transpiration
positive pressure that forms in the roots as the roots uptake water from the soil by osmosis
root pathways
apoplasmic
movement through cell walls, expect when crossing endodermis
root pathways
symplasmic
movement through cytoplasm and plasmodesmata
