E=(w_i-w_a)g_c

g_c-> leaf conductance

θ=point of light saturation

φ=photosynthetic efficiency (slope)

LCP=  Light Compensation Point (where respiration = photosynthesis

R_d= Dark Respiration

Differences between High Light and Low Light adapted plants?

High Light= higher φ, higher θ, LCP higher, more R_d

Low Light= lower φ, lower θ, LCP lower, less R_d 

Dark Reaction

Always going on (in light and dark)

Takes place in stroma

1) Carbon Fixation

2)Formation of sugars

3) Regeneration of RuBP (Carbon Acceptor)

First Phase-> represents PI, CO₂ limited, greater slope than phase 2, V_cmax

Second Phase-> represents PII, RuBP ATP and NADPH limited), J_max

max rate of Rubisco carboxylation

Initial slope of A-c_i curve

max rate of electron transport for RuBP

can be measured with flourescence

P680-> good oxidizer, splits H₂O

Light excites electrons

Plastiquinone transports electrons to Photosystem I

P700 -> reduces e^- to produce NADP

uses light energy to transfer electrons from plastocyanin to ferredoxin

Ferredoxin produces NADP

Where are the three places light energy goes?

Heat Dissipation - φ_d

Flouresencese - φ_f

Photosynthesis - φ_p

φ_p+φ_f+φ_d=1 for each photon

How much light energy is utilized by photosynthesis (max quantum yield)

probability that the energy of a photon absorbed will be used in photosynthesis

Water Potential

Ψ_w=Ψ_p+Ψ_π+Ψ_m+Ψ_g

Ψ_p

Ψ_π

Ψ_m

Ψ_g

Ψ_p -> pressure

Ψ_π -> osmotic

Ψ_m -> matric

Ψ_g -> gravitational

If ψ_w outside cell falls below ψ_π, turgor pressure falls to 0

The ψ_w that causes pressure to fall to 0 is turgor loss point (observed as wilting)

Osmoregulation

Increase Osmotic Pressure, allows plants to maintain turgor pressure at low ψ_w levels, which prevents wilting

shows drought tolerance

Ability to change volume of cell wall

water is taken by roots and is driven through the plant by transpiration via the leaves

Straw like

Gravitational Potential 

becomes less negative, increases by .1 MPa for every 10m incriment in height

Matric Potential

surface interactions w/ soil particles

different particle sizes affect ψ_m

larger soils make it easier for a plant to draw water out (bigger particles have more space between them)

however, large soils have a more difficult time of retaining water

W_d

W_f

W_a

W_e

W_s

W_d -> H₂O gained from drininking

W_f-> H₂O gained from food

W_a-> H₂O gained from air

W_e -> H₂O lost through evaporation

W_{s ->} -> H₂O lost from secretions/excretions

δ¹³C = (¹³C_sample/¹²C_sample) - (¹³C_standard/¹²C_standard)

                                                           x1000

(¹³C_standard/¹²C_standard)

Thermodynamic

Kinetic

Due to differences in reation rates between heavy and light isotopes

light isotope reacts faster than heavier

C₃ and C₄ plants exhibit differences in δ¹³C

Freshwater and Marine algae differ in δ¹³C

Most plants (around 95%)

Photorespirates -> loses carbon

nearly eliminates photorespiration

Costs ATP though

exhibit spatial variability in δ values

caused by pattern of rainfall vs distance inland (F_v) , which is a function of rainfall amount and partitioning between runoff and evapotranspiration

When Evapotranspiration > Precipitation

δ increases in relation to distance inland (F_v)

Plants need to synthesize everything

therefore they must aquire elements (ie the building blocks) required to synthesize compunds

C

O

H

N

Apoplastic -> movement of water through dead cells

Symplastic -> movement of water through living cells

Interception 

Mass Flow

Diffusion

conservation -> ex. leaf fall, brings nutrients in leaves back to soil

ex. plants limit their growth if there is low nutrient avaliablity

Microrhyzziahl association -> N fixation

Symbioses

A high root to shoot ratio may indicate nutrient deprived soil 

more roots in a nutrient deficient soil 

less roots in a nutrient rich soil 

Herbivory

Carnivory

Omnivory

Detritivory

C:N ratio is usually very different in the food matter because tissue composition of the animal is different than the tissue composition of the thing its eating

except for carnivores