Ecophysiology
of plants
Biology, Bachelor year 2
Radboud University
Ilona de Weert
,Inhoud
Carbon: .................................................................................................................................................... 2
Light ......................................................................................................................................................... 9
Nutrients:............................................................................................................................................... 14
Water ..................................................................................................................................................... 18
Mycorrhizae:.......................................................................................................................................... 19
Space ..................................................................................................................................................... 22
Germination .......................................................................................................................................... 23
Growth and allocation ........................................................................................................................... 23
Drought.................................................................................................................................................. 27
Flooding stress:...................................................................................................................................... 31
Fermentation:........................................................................................................................................ 34
Salinity stress ......................................................................................................................................... 41
Plant in the “real world” ........................................................................................................................ 44
Biodiversity – ecosystem functioning.................................................................................................... 49
,Acquiring resources
How to plant get al the stuff they need?
Resources: abiotic and biotic environmental factors that vary over time and space and that are
consumed by organisms (everything that can be limited) e.g. light, carbon, nutrients, space, water.
Carbon:
- Available as CO2 and as organic compounds
- Primary building block (90% of plant dry mass will be carbon)
Plants take up CO2 -> photosynthesis (to fix energy). So: also light is coupled to carbon fixation.
Different types of photosynthesis have evolved: C3, C4 and CAM.
C3: just a normal grassland like in the Netherlands, climate not extreme, a lot of water (temperate
climate).
CAM: temperature are very high and water is a short demand.
C4: intermediate, so high temperature but a part of the year there is a lot of water like savannas and
tropical forest.
Intermezzo: to understand the function of plants and organisms, it is necessary to know and
recognize plant morphology and anatomy.
1. Leaf: stromata, hairs with basal cell and topcell, epidermis (as skin), modified trichome
(mushroom shaped -> making leaves sticky or typical smell).
2. Trichomes (hairs), but different types. Defense against animals to keep the air at the surface
of the leaves. So wind does not effect to loose water.
3. Cross section of above ground. The vascular bundles are around in the area where are
parenchymal cells (large cellular bundles). Very outside the xylem, and bit to middle phloem.
4. Large hairs and glands. Cross section of a leaf. Elongated cells next to each other (palacate
parenchyma where chloroplast are abundant and thus on top) under it is more lose and
spongy.
5. Anther with a developing pollen.
6. In the background a stoma with in front a smooth surface -> epidermis. But those in the
middle are fungus that grows on top of the leaf. These are hyphen.
7. Stem because of the parenchyma in the middle. Red: xylem, green is phloem en then cortex
and then epidermis.
8. Root. Endodermis is the dark circle, and inside there are xylem and phloem. Outside the
circle is the parenchyma.
C3, C4 and CAM differ in dark reactions.
, Dark reaction:
Carbon input is fixated into phosphoglycerate. Then you need ATP and NADPH (that comes from the
light reaction) and that reduction power the glyceraldehyde-3-phosphate (where fixed carbon comes
out as sugars).
Rubisco is very important enzyme for this cycles.
C3 photosynthesis:
- Palisade and spongy parenchyma in the leaf. Palisade takes up light and what is left is used
by the spongy parenchyma. Also below so near spongy parenchyma are stomata.
- CO2 fixation during light period.
- Fixation of CO2 by Rubisco
- Relatively high photorespiration by Rubisco. For every 3 fixed carbon molecules by rubisco,
so there is 1 time that the photoreaction takes place.
Rubisco reacts with O2 than with CO2. So in the end, it is not fixing carbon, but releasing
carbon. So not only in chloroplast, but also in peroxisomes and mitochondria.
- Mainly happening at high O2/CO2 ratios and higher temperatures. To more O2 is available,
the less CO2 is available. So the stronger the green part is happening. This is also with high
temperatures. With higher temperatures there is a higher concentration of O2 in the air. So
green is also going more easily.
- Competition with carboxylation.
- Evolutionary relict or overflow mechanism? Just a left over in the time where CO2-
concentrations were much higher. Also spending ATP and NADPH.
- Role in nitrate metabolism
of plants
Biology, Bachelor year 2
Radboud University
Ilona de Weert
,Inhoud
Carbon: .................................................................................................................................................... 2
Light ......................................................................................................................................................... 9
Nutrients:............................................................................................................................................... 14
Water ..................................................................................................................................................... 18
Mycorrhizae:.......................................................................................................................................... 19
Space ..................................................................................................................................................... 22
Germination .......................................................................................................................................... 23
Growth and allocation ........................................................................................................................... 23
Drought.................................................................................................................................................. 27
Flooding stress:...................................................................................................................................... 31
Fermentation:........................................................................................................................................ 34
Salinity stress ......................................................................................................................................... 41
Plant in the “real world” ........................................................................................................................ 44
Biodiversity – ecosystem functioning.................................................................................................... 49
,Acquiring resources
How to plant get al the stuff they need?
Resources: abiotic and biotic environmental factors that vary over time and space and that are
consumed by organisms (everything that can be limited) e.g. light, carbon, nutrients, space, water.
Carbon:
- Available as CO2 and as organic compounds
- Primary building block (90% of plant dry mass will be carbon)
Plants take up CO2 -> photosynthesis (to fix energy). So: also light is coupled to carbon fixation.
Different types of photosynthesis have evolved: C3, C4 and CAM.
C3: just a normal grassland like in the Netherlands, climate not extreme, a lot of water (temperate
climate).
CAM: temperature are very high and water is a short demand.
C4: intermediate, so high temperature but a part of the year there is a lot of water like savannas and
tropical forest.
Intermezzo: to understand the function of plants and organisms, it is necessary to know and
recognize plant morphology and anatomy.
1. Leaf: stromata, hairs with basal cell and topcell, epidermis (as skin), modified trichome
(mushroom shaped -> making leaves sticky or typical smell).
2. Trichomes (hairs), but different types. Defense against animals to keep the air at the surface
of the leaves. So wind does not effect to loose water.
3. Cross section of above ground. The vascular bundles are around in the area where are
parenchymal cells (large cellular bundles). Very outside the xylem, and bit to middle phloem.
4. Large hairs and glands. Cross section of a leaf. Elongated cells next to each other (palacate
parenchyma where chloroplast are abundant and thus on top) under it is more lose and
spongy.
5. Anther with a developing pollen.
6. In the background a stoma with in front a smooth surface -> epidermis. But those in the
middle are fungus that grows on top of the leaf. These are hyphen.
7. Stem because of the parenchyma in the middle. Red: xylem, green is phloem en then cortex
and then epidermis.
8. Root. Endodermis is the dark circle, and inside there are xylem and phloem. Outside the
circle is the parenchyma.
C3, C4 and CAM differ in dark reactions.
, Dark reaction:
Carbon input is fixated into phosphoglycerate. Then you need ATP and NADPH (that comes from the
light reaction) and that reduction power the glyceraldehyde-3-phosphate (where fixed carbon comes
out as sugars).
Rubisco is very important enzyme for this cycles.
C3 photosynthesis:
- Palisade and spongy parenchyma in the leaf. Palisade takes up light and what is left is used
by the spongy parenchyma. Also below so near spongy parenchyma are stomata.
- CO2 fixation during light period.
- Fixation of CO2 by Rubisco
- Relatively high photorespiration by Rubisco. For every 3 fixed carbon molecules by rubisco,
so there is 1 time that the photoreaction takes place.
Rubisco reacts with O2 than with CO2. So in the end, it is not fixing carbon, but releasing
carbon. So not only in chloroplast, but also in peroxisomes and mitochondria.
- Mainly happening at high O2/CO2 ratios and higher temperatures. To more O2 is available,
the less CO2 is available. So the stronger the green part is happening. This is also with high
temperatures. With higher temperatures there is a higher concentration of O2 in the air. So
green is also going more easily.
- Competition with carboxylation.
- Evolutionary relict or overflow mechanism? Just a left over in the time where CO2-
concentrations were much higher. Also spending ATP and NADPH.
- Role in nitrate metabolism
