January 7 ~Feb1 2013
Midterm date: Monday Febuary 4 2013. 5-7pm
Module 2: Begins on Tuesday Feb 5 . th
Total: 12 lectures
1-2: Tree of life-plants
3-4 Plant cells and plant tissues
5-6. From seed to tree
7-8. From tree to seed
9. Transport in plants
10. Plant nutrition and soils
11. Plant defense
12. Plant life on the edge.
Lecture 10 notes (Plant nutrition & soils)
A) Nutrients necessary for plant life
Sugar: carbon dioxide & light & water
Water & oxygen
From high elements needed to low elements needed
then macronutrient:N>K>Ca>Mg>P>S>Si. Required in large amounts
Then micronutrient: Cl>Fe>B>Mn>Na>Zn>Cu>Ni>Molybdenum(mo)
required in smaller amounts
Absence prevents plant from completing its life cycle
Most limiting under average condition: N,P,K
Dunes lack N=no plant growth
When ice melt, there is no bacteria in the sugar=no N=no plant growth Nitrogen (unreactive)
Essential building block for life, basic metabolism, photosynthesis
Atmospheric overabundance (78% nitrogen gas)
Bioavailability through bacteria.
Young soils (dune, volcanic soil, ice glaciers) limit N until bacteria build up.
Building blocks of life: amino acid into protein
Glycine, Alanine, Serine, Threonine, Cysteine, valine, leucine, isoleucine, methionine,
proline, phenylalanine, tyrosine, tryptophan, apsartic acid, glutamic acid,
asparagine, glutamime. Histidine, lysine, arginine. (C,H,O,N elements)
N present in:
Photosynthesis: chlorophyll A-H C3 chlorophyll B: COOH
Energy currency: NADP
Inheritance: nucliec acids. ATCG
ATP so let’s start with
atmosphere nitrogen gas. Nitrogen gas has 3 ways to turn into reactive nitrogen.
Path 1: N 2 lightning> into soil> nitrate
Path 2: N 2 Nitrogen fixation soil bacteria>decomposition>amino
Path 3: N 3 Nitrogen fixation symbionts rhizobia in plants>plant is consumed by
animal>animal excretion into soil>uric acid & urea> ammonia>nitrite>nitrat
Now let’s see how nitrate turns back into unreactive nitrogen gas
Path 1: Nitrate>denitrifying bacteria>N 2
Path 2: Nitrate> absorbed by plants>path 3 .
Remember, 78% of nitrogen gas!
There is not a lot of nitrate in soil because of competition.
Nitrate is a bio accessible form Phosphorus-hard to take up by plants-low bio availability- reactive with soil.
Promotes early plant growth and root formation: P have role in cell division
Essential for flowerin and fruiting.
P is found in: inheritance (nucleic acids RNA&DNA), ATP-3P present , NADP-3P
present, Energy currency.
Important in process of sugar and starch production
Opening & closing stomata
Increase plant disease resistance, assist in enzyme activiation& phtosynthesis
Increase size& quiality of fruits
Bioavailability in K ions. Relatively immobile in soils. Better absorbed than
Phosphorus. (e.g clay & hummus tied to soil particle)
How to recognize P,K,N deficiencies:
Healthy leaf: all green
K-deficient: yellow outside
N-deficient: yellow inside.
B) Nutrients availability in soils
To take up a nutrient, it must be dissolved into cation and anion
caTion as in ca+ion (positive) and anion (negavie)
Typical nutrient cations and anions:
cations: K+,NH4+, Mg2+, Ca2+,Zn+ Mn2+,Fe+,Cu+
Nearly all P reacts with soil particles other than clay and organic material making it
insoluble making it percipitates out of soil solution making P unavailable.
Cation Exchange Capacity (CEC) of soil
In clays & humus: have more nutrients because higher cation exchange capacity,
higher negatively charged sites. In sand: have lower nutrients