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.