1. Lecture 3 Plant nutrition
3.4d

2. Plants develop extensive root systems

3. Different areas of the root absorb different mineral ions
- absorption of calcium in barley
is restricted to apical region
- iron is taken up either at apical region (barley) or over entire root surface (corn)
- potassium, nitrate, ammonium,
phosphate are absorbed at all
locations of the root
- root apex absorbs ammonium more rapidly than elongation zone (corn, rice)
- root hairs are the most active
in phosphate absorption
→ strong demand of nutrients in apical region (cell elongation)

4. Root infected with ectotrophic mycorrhizal fungi
Example: only
tree species;
gymnosperms
and woody
angiosperms
- fungal hyphae surround the
root to produce a dense
fungal sheath and penetrate
the intercelluar spaces
of the cortex to form the
Hartig net
- total mass of fungal hyphae
may be comparable to the
root mass itself

5. Association of vesicular-arbuscular
mycorrhizal fungi
- fungal hyphae grow into
the intercellular wall
spaces of the cortex and
penetrate individual
cortical cells
- as they extend into the cell,
they do not break the
plasma membrane or the
tonoplast of the host cell
- instead, the hypha is
surrounded by these
membranes and forms
structures known as
arbuscules, which participate
in nutrient ion exchange
between the host
plant and the fungus

6. Nutrition - Summary
macro- and micronutrients are essential for plant life
- nutritional disorders occur because nutrients have roles in
energy storage, plant structure, enzyme cofactors, electron
transfer reactions
- mineral nutrition can be studied through the use of solution
culture
- to prevent development of deficiencies, nutrients may be
added back to the soil/plant through fertilizers
- size of soil particles and cation exchange capacity determine
the reservoir for water and nutrients
- soil pH affects availability of mineral elements to plants
- plants develop extensive root system to obtain nutrients
- plant roots form associations with mycorrhizal fungi
- hyphae facilitate the acquisition of mineral elements (P)
- in return, plants provide carbohydrates to mycorrhizae