Water relations and Energy balance. Ψ= Water potential Ψ π = osmotic potential Ψ p = pressure potential Ψ g = gravitational potential Ψ m = matric potential.

Water relationsand

Energy balance

Ψ=Water potential

• Ψ π = osmotic potential• Ψ p= pressure potential

• Ψ g= gravitational potential • Ψ m= matric potential

Ψ = Ψ π + Ψ p + Ψ m + Ψ g

-13.7 Mpa, (50 % relative humidity)

-2.3

-1.9

Water potential

-1.5

-0.1 (moist soil)

Whole-plant adaptations to low water availability

• Drought avoidance

• Drought deciduous

• Drought tolerant

Anatomical and morphological adaptations

• Leaf size and shape

• Stomata properties

• Characteristics of the cuticle

• Pubescence

• Vascular tissue

• Roots

Latent heat

Energy balance

Convection

Conduction

Leaf boundary layer

Short wave radiant energy

Long wave radiant energy

Energy Balance

0 EHRn Rn = the net amount of radiant heat energy

H the sensible heat (conduction +convection) loss

λE = latent heat loss