Day 6 Plant Nutrition

Are plants autotrophs or heterotrophs

mainly autotrophs

What are autotrophs

don’t consume other organisms

Major source of plants biological material

CO2

• almost all C6H12O6 is made from C and O atoms from CO2

What makes up 90% of plant mass

carbon and oxygen atoms

What makes up 6% of plant mass

hydrogen from H2O

Where do plants get the remainder of their essential nutrients

1. macronutrients - 0.1%-1.5% of total mass

2. micronutrients - 0.01% or less of total mass

• normally extracted from soil

List of macronutrients

1. nitrogen

2. phosphorus

3. potassium

4. sulfur

5. calcium

6. magnesium

(know top three)

List of micronutrients

1. iron

2. chlorine

3. manganese

4. boron

5. zinc

6. copper

7. nickel

What are the effects of nutrient insufficiency

insufficient levels of macro and micronutrients leads to poor growth, damaged tissue, etc.

What is the composition of soil

soil is a mix of inorganic and organic materials

How are inorganic particles created

created by erosive forces and biological action

What is soil texture determined by

particle size

• larger particles hold less water but provide more oxygen than small particles

What is humus

organic material consisting of dead organismal tissue and animal waste

What living organisms does soil host

1. animals

2. fungi

3. protists

4. prokaryotes

5. plant roots

Does the top or bottoms soil have more organic material

The top (humus)

• decreasing humus content with increasing depth

Why is topsoil loss important

it’s crucial for a healthy and stable plant community

Topsoil can be lost when reduce vegetation is combined with:

1. wind

2. rain

3. flooding

Where does most nutrient uptake occur

in zone of maturation at new root hairs

What does new root growth mean

means newer soil that is higher in nutrients

What are mycorrhizal fungi

are mutualists with plants

• symbiotic relationship

• fungi infiltrate roots

What do fungi provide plants

essential nutrients

1. amino acids for N

2. phosphates for P

What do plants provide fungi in return

sugars for energy

Why do plants need nitrogen

to make amino acids and nucleic acids

Can plants use molecular nitrogen (N2)

no

What is nitrogen fixation

reducing N2 into nitrates (NO3-) and ammonia (NH3) and ammonium (NH4+)

What is nitrogen-fixing bacteria

• make NH4+ from N2

• animal waste also gives NH4+

• some are symbiotic with plants

What is nitrifying bacteria

make NO2- and NO3- from NH4+

Example of symbiotic bacteria

Rhizobia

What is Rhizobia

nitrogen-fixing bacteria that are mutualists with plants

Rhizobia provides ____ for plants and plants provide _____ in return

1. bacteria provide ammonia

2. plants provide sugar

Where does Rhizobial bacteria live

within parenchyma cells in the roots

What are Legumes

major plant group that hosts rhizobia

1. peas

2. soybeans

3. clover

4. alfalfa

What major plant group hosts rhizobia

legumes

Soil particles in clay

organic, clay has - charge and + charge ions that stick to these

What tends to dissolve in water

ionic nutrients

What forms insoluble complexes and example

some - and + ions

• ex. phosphate with metal ions

How does clay-heavy soils hold lots of nutrients

due to strong - charge and water retention

What can affect nutrient availability

pH (H+ concentration)

How does pH (H+ concentration affect nutrient availability

H+ can displace cations on soil particles, putting them in solution

(can be taken up by plants or leached away)

How can local pH be affected

by CO2 release or proton pumps

CO2 + H2O → -< H+ + HCO3-

What is cation exchange

when H+ displaces cations on soil particles

Proton pump’s role in nutrient uptake

create high H+ immediately outside root hairs

Result of high H+ outside root hairs

electrochemical gradient allows uptake of nutrients

(cations via electrical gradient)

(anions via secondary active transport with H+)

Examples of parasitic plants

1. mistletoe

2. dodder

3. ghost plant

Mistletoe parasitic plant

• many species around the globe

• hemi parasitic on other plants - photosynthetic

• initially independent of host, later grow haustoria

Dodder parasitic plant

• Genus cuscuta

• holoparasite on other plants

• not photosynthetic - no chlorophyll

• no leaves - stems and flowers only

• use haustoria to pull nutrients from host plant

Ghost plant parasitic plant

• Monotropa uniflora, aka ghost pipe plant

• holoparasite on mycorrhizal fungi

• not photosynthetic - no chlorophyll

• reduced leaves - likely vestigial

What are epiphytes

grow on other plants but are not parasitic

Traits of epiphytes

1. more common in humid and rainy environments

2. roots modified for attachment, photosynthesis

3. may trap water and nutrients

What are carnivory plants

trap and digest animals for protein content

(water traps, sticky traps, snap traps)

Where do you find carnivory plants most

in low N environments