1. Chapter 37.
Plant Nutrition
AP Biology 2005-2006

2. Nutritional needs
 Autotrophic does not
mean autonomous
 plants need…
 sun as an energy source
 inorganic compounds as
raw materials
 water (H2O)
 CO2
 minerals
AP Biology 2005-2006

3. Macronutrients
 Plants require these nutrients in
relatively large amounts
 C, O, H, N, P, K, Ca, Mg, S
AP Biology 2005-2006

4. For what & from where?
C synthesis CO2
O synthesis CO2
H synthesis H2O
N protein & nucleic acid synthesis soil & fertilizer
P nucleic acids, ATP, phospholipids soil & fertilizer
K stomate control, water balance soil & fertilizer
Ca cell wall & membrane structure, regulation soil
Mg chlorophyll soil
S proteins, enzymes soil
AP Biology 2005-2006

5. Local Long Island soil issues
Quartz silica based soils
- low in P
- can be acid
Acid soils bind up
mineral ions
↑pH by adding lime
AP Biology Granite 2005-2006

6. Micronutrients
 Plants require in very small amounts
 primarily cofactors
AP Biology 2005-2006

7. Nutrient deficiencies
 Lack of essential nutrients
 exhibit specific symptoms
 dependent on
function of nutrient
 dependent on
solubility of nutrient
AP Biology 2005-2006

8. Take 2
Magnesium deficiency fertilizer pellets
& call me in
the morning
 Symptoms
 chlorosis = yellowing of leaves
 what is magnesium’s function?
AP Biology 2005-2006

9. Chlorophyll
Why does magnesium
deficiency cause chlorosis?
The chlorosis shows up in older
leaves first, because plant moves
Mg to newer leaves. Why?
AP Biology 2005-2006

10. Water & mineral uptake
 Water uptake  Cation uptake
 plants cannot extract  cation uptake is aided by
all water from soil, H+ secretion by root cells
only free water (proton pump)
 osmosis  active transport
AP Biology 2005-2006

11. The role of soils
 Plants are dependent on soil quality
 texture / structure
 relative amounts of various sizes of soil particles
 composition
 organic & inorganic chemical components
 fertility
AP Biology 2005-2006

12. So don’t rake
Importance of organic matter your lawn or
bag your leaves
 Topsoil
 most important to plant growth
 rich in organic matter
 humus
 decomposing organic material
 breakdown of dead organisms, feces, fallen leaves &
other organic refuse by bacteria & fungi
 improves soil texture
 reservoir of minerals
 organisms
 1 tsp. of topsoil has ~5 billion
bacteria living with fungi,
algae, protists, insects,
earthworms, nematodes
AP Biology 2005-2006

13. Soil health as a global issue
Not taking care of soil health has
far-reaching, damaging
consequences
 1920’s Dust Bowl
 lack of soil conservation
 growing wheat
 raising cattle
 land exposed to
wind erosion
 drought
AP Biology 2005-2006

14. Soil health as a global issue
 Soil conservation & sustainable agriculture
 maintaining healthy environment
 production of food supply
 economically viable farming industry
“A sustainable agriculture does not deplete soils or people.”
– Wendell Berry
contour plowing cover crops crop rotation
AP Biology 2005-2006

15. Global issues
 fertility
 erosion
 irrigation
 forestry destruction
AP Biology 2005-2006

16. AP Biology 2005-2006

17. Fertilizers
 “Organic” fertilizers
 manure, compost, fishmeal
 “Chemical” fertilizers
 commercially manufactured
 N-P-K (ex. 15-10-5)
 15% nitrogen
 10% phosphorus
 5% potassium
AP Biology 2005-2006

18. Nitrogen uptake
 Nitrates
 plants can only take up nitrate (NO3-)
 Nitrogen cycle by bacteria
 trace path of nitrogen fixation!
root
AP Biology 2005-2006
What will the plant use N for?

19. Soybean root nodules
 N fixation by Rhizobium bacteria
 symbiotic relationship with bean
family (legumes)
AP Biology 2005-2006

20. Plow it under?
Increasing soil fertility Why would you
that?
 Cover crops
 growing a field of plants just to
plow them under
 usually a legume crop
 taking care of soil’s health
A man…
 puts nitrogen back in soil outstanding
in his field
AP Biology 2005-2006
erosion control, too

21. Some plant oddities…
AP Biology 2005-2006

22. Parasitic plants
 tap into host plant vascular system
Indian pipe
Mistletoe
AP Biology 2005-2006

23. Plants of peat bogs
 High acid environment
 most minerals & nutrients bound up &
are not available to plants
 must find alternative sources of nutrients
AP Biology 2005-2006

24. Carnivorous
plants
Sundew Venus fly trap Pitcher plant
Are they really
carnivores?
AP Biology 2005-2006

25. AP Biology Pitcher plant 2005-2006

26. Uses of peat
AP Biology 2005-2006

27. Any Questions??
AP Biology 2005-2006