Week 3 Flashcards
What are the 6 macronutrients?
Nitrogen
Phosphorus
Potassium
Sulphur
Magnesium
Calcium
What are John Woodward’s conclusions?
Woodward concluded that mineral matter nourishes plants.
What were the impact of John Woodward conclusions?
These conclusions layed the foundation for the study of plant mineral nutition
What experiement did John Woodward do?
He compared plant growth in water different amounts of ‘mineral matter’ to test the assumption that water is a plant’s sole requirement.
What were the results of John Woodward’s experiments?
Spring water - plant weight increased by 55%
Rain water - plant weight increased by 62%
Thames River Water - plant weight increased by 93%
What is the “law of minimum”?
Growth of the plant will always be determined by the limited nutrient
When did Lawes and Gilbery start investigating plant nutrition?
They started in 1843 at Rothamsted, which is still researching today
Where does nutrient assimilation take place?
They take place across the surface of the plant or through the root system of vascular plants
What are the 8 micronutrients?
Iron
Nickel
Manganese
Copper
Molybdenum
Boron
Chlorine
Zinc
Which ions of nitrogen, phosphorus, sulphur, molybdenum and boron aren’t assimilated as compounds?
Nitrogen - NO3 -, NH4 +
Phosphorus - HPO4 2- , H2PO4
Sulfur - SO4 2-
Molybdenum - MoO4 2+
Boron - H3BO3
What is requred for the transportation of charged ion?
They require proteins to cross membranes
How do roots increase effciency?
They increase the surface area for absorption
What are the similarities between microvilli and roots?
They are structurally similar but inverse as they need to absorb nutrients in rather than absorb nutrients out into the blood
What are the adaptations to enhance nutrient capture?
Biochemical response - root exudates
Fungal symbiotic partners - mycorrhizae
Developmental responses - cluster roots
Prokaryotic symbiotic partners - Biological nitrogen fixation
How does soil pH change around the world?
Deserts and other dry areas are mildly alkaline comapred to forests which are strongly acidic
How does soil pH impact nutirents?
Different pHs impact the percentage of uptake of soil nutirents with each nutirent having a more optimum pH
What things affect soil fertility?
Erosion, rainfall patterns, cultural practices, soil biodiversity, soil pH and atmospheric gases
What are the main 3 elements in fertilizers?
Nitrogen
Phosphorus
Potassium
What are the two types of fertilizers?
Natural - waste products
Artifical - refinded blends of nutirent salts
Are resources constant around the planet?
No, different regions have different amounts of resources. So areas like USA have greater supply of K2O than demand but has lower N than demand compared to Russia/Eastern Europe which has greater supply of both K20 and N than demand
How much is the fertilizer trade worth?
$231 billion dollars in 2021
What factors impact the amount of fertilizer used?
Species of plant
Soil characteristics
Cultivation practices
Abiotic and biotic factors
Financial considerations
Interactions between nutrients
What are the problems of fertilizers?
Nitrogen fixation is energy demanding
Phosphate and potash mining is destructive
Huamn and animal waste can spread disease
Transport requires energy
Nutrient runoff pollutes waterways and can lead to eutrophication
Nitrous oxide derived from fertilizer is a major greenhouse gas
Where are minerals naturally come from?
Rock weathering
Decaying matter
Organic matter
Inorganic matter
How much does food production increase inbetween 1960 and 2000?
1.8x10^9 to 3.5x10^9
How much does nitrogen fertilizer use increase inbetween 1960 and 2000?
10x10^12g (10 Tg) to 88x10^12 (88 Tg)
How abundant is nitrogen in plants and the atmosphere?
Most abundant elements in atmosphere
4th most abundant element in a plant after C, H and O
Why is nitrogen is important?
In amino acids
Nucleic acids
Chlorophyl
Other small molecules
What element is often the limiting nutrient for plants?
The limiting nutrient for plant growth is nitrogen
What is the difference between nitrous oxide and nitric oxide?
Nitrous oxide - N2O
Nitric Oxide - NO
What is the difference between nitrous acid and nitric acid?
Nitrous acid - HNO2
Nitric acid - HNO3
What do nitrifying bacteria do?
Convert ammonium to Nitrogen dioxide to nitrate
This releases energy
What do plants to produce organic nitrogen?
Using energy and the enzyme nitrate reductase
NO3- to NO2- to NH4+ to R-NH3
Do plants prefer NH4+ vs NO3-?
Plant preferences for NH4+ vs NO3- vary by species, other metabolic processes, temperature, water, soil pH
What are HATS?
High affinity transporters - can transport either ammonium, nitrate, amino acids and urea depending on the transporter in high concerntrations
What are LATS?
Low affinity transporters - can transport either ammonium, nitrate, amino acids and urea depending on the transporter in low concerntrations
What happens to nitrate within the plant?
Other Channels contribute to nitrate transport within and between cells
Name Ammonium channels?
AMT 1.1 = HATS
Name nitrate uptake channel?
NAR 2.1 = HATS
NRT 1.2 = LATS
Name an amino acid uptake channel?
AAP1
Name an urea uptake channel?
DUR 3 - HATS
TIPS - Passive
What happens to uptaken NH4+?
It gets assimilated into organic compounds like glutamine
What happens to uptaken R-NH3?
It gets assimilated into NH4+?
What is glutamine used for?
It is converted into all other nitrogen containing compounds
What is remobilization?
Amino acid recycling and photorespiration which produces NH4+
What happens to recycled and uptaken NH4+?
It is converted into glutamine using glutamate by glutamine synthetase (GS)
What happns to the glutamine?
Some is incorporation into nitrogen-containg compounds
Some of the nitrogen is split and bonds with 2-oxoglutarate to glutamate using glutarate aminotransferase (GOGAT) which then bonds wirh NH4+
Can nitrogen go through GS many times?
Yes, they can go through GS many times many times as amino acids are recycled during growth and senescence and relewased due to photorespiration
What does a plant do in response to nitrogen deficit?
Activation of some NO3- and NH4+ transporters
Preferential growth of root relative to shoot
What are metabolic adaptations to low nitrogen?
Decreased accumulation of N-rich chlorophyll
Increased accumulation N-free anthocyanins
Smaller pools of N-containing compounds (amino acids)
Larger pools of N-free compounds (starches, organic acids)
Accelerated senescence and nitrogen remobilization
What happens to roots when nitrogen is abundant?
Plants allocate less biomass to their roots