Biology 633Environmental Plant Physiology

Tropical rainforest

Alpine tundra

Desert

aderfasi@yahoo.com

Study of how the environment affects the function of plants

Module overview Discuss interplay between the genetic

potential of plants and environments in which they grow

Impact of short-term changes in the environment on physiology, morphology and growth of plants

Stress response, acclimation and adaptation of plants in response to changes in environment

16 lectures and 4 practical sessions

Overview of lectures Introduction to Environmental Plant Physiology Response of plants to their environment Plant growth analysis Photosynthesis; mostly C3 plants C4 and CAM plants Respiration Water, drought and plant growth Adaptation of plants to growth on the sea floor

Recommended texts Lambers, Chapin & Pons (1998) Plant

Physiological Ecology Atwell, Kreidemann & Turnbull (1999) Plants in

Action Fitter & Hay (1987)

Environmental Physiology of Plants Larcher (1995)

Physiological Plant Ecology Taiz & Zeiger (1991)

Plant Physiology

Lecture 1Learning objectives Define Physiological Ecology Appreciate dynamic nature of the

plant/environment interaction Be familiar with variations in

environmental conditions between and within habitats

Importance of time scales in determining response of plants to their environment

Plants: static or dynamic?

Visually stunning

Their structures respond to changes in environment (e.g. shade)

Their metabolism is constantly changing response to large variations in environment

Temporal variation in temperature

…….and light intensity

Global environment is also changinge.g. greenhouse gases, temperature,

nutrients, UV-radiation

Year

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Rising atmospheric CO2 concentrations

…….enormous flow of CO2 in and out of leaves

…….and these are cells that remove CO2 from the atmosphere

What is Environmental Plant Physiology (EPP)?

Study of how the environment affects the function of plants

Requires knowledge of biochemistry, physiology, anatomy and morphology of plants

Provides causal, mechanistic explanations for ecological questions such as:- Why does a species live where it does?- How does it survive, and why is that species absent from other environments?

Question: how do plants cope with excess light when it is very cold?

e.g. avoid the morning sun

Question: how do plants cope with soils deficient in phosphorus?

e.g. grow cluster roots

Question: how do plants cope with excessive salt?

e.g. sequester salt in salt bladders

Question: how do plants manage to grow in deep shade? e.g. use light flecks

Environmental Plant Physiology & Agriculture/Forestry EPP is also closely linked to the study of plant

performance in agriculture Agricultural production is limited in many countries by

stresses such as drought, nutrient availability, salinity, temperature

Need to develop crops that are less sensitive to those stresses, so we can grow them in less favorable environments

Understanding required of the physiological mechanisms that enable plants to cope

Question: what mechanisms enable the barley variety on the left cope better with manganese deficiency than the variety on the right?

Environmental Plant Physiology & Global Change

Need to predict effect of future changes in global environment on crop productivity, competitive interactions among species etc

Also need to know the extent to which plants could reduce future increases in elevated atmospheric CO2

Photo-synthesis

Plant respiration

Global atmospheric CO2 concentrations: importance of plants

Environmental Plant Physiology & Molecular Biology

Mutants/transgenics may allow a rigorous test of hypotheses

e.g. transgenic tobacco plants to assess importance of Rubisco (CO2 fixing enzyme in plants) for plant growth

Why so few plant species in one place?

FiltersSome species do not

occur in the UK, because they were never introduced

Others arrived, but never made it to maturity

Some evolved locally, or were introduced and ‘made it’

Filters are constantly changing/interacting

Response of plants to their environment: time scales Time scale of physiological response is

important in determining how a plant copes with changes in the environmente.g. short- and long-term changes in temperature

Stress response Acclimation response Adaptation/evolution response

Stress and acclimation (of an individual) vs. adaptation (a long-term genetic response)