Plant Nutrition. Nutritional needs Autotrophic does not mean autonomous… plants need… sun as...
-
Upload
sydney-benson -
Category
Documents
-
view
220 -
download
1
Transcript of Plant Nutrition. Nutritional needs Autotrophic does not mean autonomous… plants need… sun as...
Plant Nutrition
Nutritional needsAutotrophic does not mean autonomous…
plants need…
sun as an energy source
inorganic compounds as raw materials:
water (H2O)
CO2
minerals
Plants require these elements in
relatively large amounts:
Think….“C H O P S N K”
Plus: Ca & Mg…
We call these:
Macronutrients
For what & from where?
Chlorophyll
Why does magnesium
deficiency cause the yellowing of
leaves ?
Symptoms of Deficiencies
MOBILE-
Some nutrients are more mobile than others…
Symptoms show up in older parts first.Shunted to younger parts “preferentially”.
IMMOBILE- Symptoms show up in younger parts first.
Get “stuck” in the older part….
Example: Mg
Example: Fe
Water & mineral uptake
Water uptake
plants cannot extract all water from soil,only free waterosmosis
Cation uptakecation uptake is aided by H+
secretion by root cells
(proton pump)
Campbell Animations
Fertilizers
“Organic” fertilizers
manure, compost, fishmeal
“Chemical” fertilizers
commercially manufactured
N-P-K (ex. 15-10-5)
15% nitrogen
10% phosphorus
5% potassium
Nitrogen uptakeNitrates
plants can only take up nitrate (NO3-)
Nitrogen cycle by bacteria
trace path of nitrogen fixation!
Nitrogen uptake continued…
The rhizobium have an enzyme called “nitrogenase”
N2 + e- + 6 H+ + 32 ATP 2NH3
Very energy consuming: 32 ATP molecules just for 2 NH3 !!!Contains “leghemoglobin” for high oxygen demands.
Roots send out “flavinoids” which attract the rhizobium.
Rhizobium, in turn, emit chemicals which stimulate root hair elongation with “infection threads for a portal of entry for the bacteria.
Another example of mutualistic symbiosis:
MycorrhizaeModified roots that are part fungus
Fungi secrete growth factors & increase surface area for greater absorption for the plant….
Plant provides and stores food for the fungus.