CAM and Epiphytes • Epiphytes: plants on plants • Abundant tropical rain forests
CAM and Epiphytes • Spanish moss (Tillandsia usneoides) • CAM plant: pineapple family (Bromeliaceae)
Comparing C3, C4, CAM plants • Exs: many Orchidaceae (70% epiphytes!)
Comparing C3, C4, CAM plants • CAM: • Succulents (deserts) • Epiphytes (tropical/subtropical areas)
Comparing C3, C4, CAM plants • Trait C3 C4 CAM • Max. Ps rate Fig. 2.12
Comparing C3, C4, CAM plants • Trait C3 C4 CAM • Max. growth rate • (optimal conditions)
Comparing C3, C4, CAM plants • Trait C3 C4 CAM • Optimum Ps temp. Fig. 2.11
Comparing C3, C4, CAM plants • Trait C3 C4 CAM • Water use efficiency (g CO2 gain per Kg H2O lost)
Applied Aspects • What crops best hot areas? • Corn/maize • Sorghum • Millet millet sorghum
Applied Aspect • Genetic engineering: C4 properties to C3 plants
Applied Aspect • Ex: rice (C3 grass) • Asia: 70% calories rice • 70% world’s poor Asian • Add PEP carboxylase gene • Yields
C3 variation (between species) • C3 plants • Heliophytes: adapted • Sciophytes: adapted Sciophyte: Who am I? Variation among C3 plants
C3 variation (within individual) European beech • Sun vs. shade leaves • Sun lvs.: Shade Sun Quercus pagoda (cherrybark oak)
Carbon isotope ratios • Isotope: different # neutrons • Ex: Carbon-12 (98.9% C) • Carbon-13 • Carbon-14 Light vs. heavy Carbon dioxide Enzyme affinity?
Carbon isotope ratios • Enzyme affinity • Lo: light CO2 used more • Hi, less discrimination • Measure ratio? Delta C-13 • Units: parts per thousand (ppt)
Carbon isotope ratios C4 • Enzyme affinity CO2 • Rubisco: • PEP carboxylase: • C3 delta C-13; -24 to -34 ppt • C4 delta C-13; -10 to -20 ppt • More negative = • more discrimination
SO WHAT?? 2 main plant species used to produce sugar (Sucrose)?
SO WHAT?? Commercial sugar (sucrose):
AHAH! ID sugar source delta C-13 ratio! • C3: -24 to -34 ppt • C4: -10 to -20 ppt Bernie Beet hands out sacks of white powder to kids..... Bernie Beet Food webs….
Herbivore Feeding Preferences Ex., rhinos Africa Black rhino: more rare (3,600). Browses
Herbivore Feeding Preferences White rhino: less rare (11,700). Grazes
Herbivore Feeding Preferences Rhino poaching: ID horn by delta C-13 ratio
Water relations • Plants need light (energy: Ch. 2) • Plants need CO2 (carbon: Ch. 2) • Plants need H2O (Ch. 3) Water potential
Water potential • Water potential: free energy • “Tendency H2O to move” • Moves hi to lo • Symbol--Greek letter: psi 4 factors influence water potential
s Water Potential • Affected by: • solutes: solute potential • hi solutes = ___ tendency move
p Water Potential • Affected by: • pressure: pressure potential • hi pressure = ___ tendency move
m Water Potential • Affected by: • charged surfaces (cell walls, clay particles): matric potential • More surfaces = ______ tendency move The Matrix potential
g Water Potential • Affected by: • gravity: gravitational potential • Height increases, tendency move _____
p g m = + + + total s Water Potential • Total H2O potential = sum factors: Units?
total Water Potential • Measurement relative: compared to standard conds. (pure H2O, sea level) • = 0 megaPascals (MPa) • megaPascal: metric system • 1 MPa = about 10 bars or 10 atmospheres
Water Potential • H2O in plants/soil has solutes: NEGATIVE What tissue in plant carries H2O?
Water transport • Xylem: H2O conducting tissue • % H2O remains in plant?
Water transport • Xylem: H2O conducting tissue • H2O in plant? How water move? ?