3933898
Descrição
Mapa Mental por Ibi Qemlas, atualizado more than 1 year ago
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Criado por Ibi Qemlas
aproximadamente 9 anos atrás
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Resource use efficiency in agriculture
- Light
- Upper Limits of Food production
- Radiation use efficiency is the limiting factor
- Radiation use efficiency is the limiting factor
- Principles of canopy structure
- Canopy structure determines (1) how much radiation is absorbed and (2)
photosynthetic efficiency of the canopy as a whole
- Canopy light interception depends on
- Canopy size (surface area)
- Canopy geometry
- Canopy size (surface area)
- Natural systems are irregular and heterogeneous because of:
- Several interacting layers of different species occupying
different niches down the canopy in time and space
- Large proportion of intercepting
elements are non-photosynthetic
- Several interacting layers of different species occupying
different niches down the canopy in time and space
- The Extinction Coefficient (k) and Beer’s Law can be used to define canopy architecture and link f and L
- Leaf Area Index (L) and Fractional Interception (f) can be used to describe vegetation capture
system and there is a functional relationship between f and L for different canopy architectures
- Complex and irregular canopies require more sophisticated techniques to be measured
- Canopy structure determines (1) how much radiation is absorbed and (2)
photosynthetic efficiency of the canopy as a whole
- Canopy structure and photosynthesis
- The higher the leaf area index the lower the the extinction coefficient (k) of the species / variety
- Upright canopies
- Disadvantage
- higher exposed ground resulting in water loss, ground evaporation and
weed risk compared to flatter leaves that cover more ground.
- achieve canopy closure later
- higher exposed ground resulting in water loss, ground evaporation and
weed risk compared to flatter leaves that cover more ground.
- Advantage
- Have more leaf area at a higher rate of photosynthesis
- higher productivity efficiency because there is a large sunlight area exposure
- Have more leaf area at a higher rate of photosynthesis
- Disadvantage
- By comparing light response curves at each point in the canopy we can
determine the proportion of the canopy that is light limited or light saturated.
- Leaves with a low extinction coefficient for radiation can have a very high leaf area in a
light-limited state and therefore a higher canopy photosynthesis rate - it doesnt saturate.
- Present
- Individual leaves display a curved response of photosynthesis to PAR – leaf response curve
- Canopies of vegetation display a generally linear response (`Conversion coefficient’) - integration of
individual leaf curves
- Individual leaves display a curved response of photosynthesis to PAR – leaf response curve
- The higher the leaf area index the lower the the extinction coefficient (k) of the species / variety
- Upper Limits of Food production
- Radiation use efficiency
- canopy photosynthesis is closely linked to radiation use efficiency (RUE)
- Environment effectors
- Nitrogen
- Temperature
- Water
- Nitrogen
- Photosynthesis determines how productive a crop can be thus It is the amount of light that a canopy
intercepts that is most strongly related to biomass and yield potential.
- Measuring
- 1. Measuring light response curves for individual leaves = controlled environment cabinet that is the
first step to assess photosynthesis within a canopy
- 2. Measuring whole canopies in controlled-environments =
allow us to control physical factors (temperature, CO2, humidity, soil moisture) whilst allowing
leaves within a canopy of vegetation to interact as if in a natural environment
- 3. Measuring canopy responses in the real world = although it is not in a controlled environment
it is in a more realistic situation
- 1. Measuring light response curves for individual leaves = controlled environment cabinet that is the
first step to assess photosynthesis within a canopy
- Conversion is required in order to adjust the biomass (g m-2) of a species for the
chemical energy values (kJ g-1) of its different constituents (carbs, lipids and
protein)
- canopy photosynthesis is closely linked to radiation use efficiency (RUE)
Anexos de mídia
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