1. Plant Nutrition

2. Nutritional needs
Autotrophic
plants need…
sun as an energy source
inorganic compounds as raw materials
water (H2O)
CO2
minerals

3. Macronutrients
Plants require these nutrients in relatively large amounts
C, O, H, N, P, K, Ca, Mg, S

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

5. Micronutrients Plants require in very small amounts
Cl, Fe, Mn, Bo, Zi, Ni, Mb
primarily cofactors for enzyme function

6. Nutrient deficiencies
Lack of essential nutrients
exhibit specific symptoms
dependent on function of nutrient
dependent on solubility of nutrient
Mineral deficiency symptoms depend not only on the role of the nutrient but also on its mobility within the plant. If a nutrient moves about freely, symptoms will show up first in older organs because young, growing tissues have more “drawing power” for nutrients in short supply. For example, magnesium is relatively mobile and is shunted preferentially to young leaves. Therefore, a plant starved for magnesium will show signs of chlorosis first in its older leaves. The mechanism for preferential routing is the source–to–sink translocation in phloem as minerals move along with the sugars to the growing tissues. In contrast, a deficiency of a mineral that is relatively immobile will affect young parts of the plant first. Older tissues may have adequate amounts, which they are able to retain during periods of short supply. For example, iron does not move freely within a plant, and an iron deficiency will cause yellowing of young leaves before any effect on older leaves is visible.
Deficiencies of nitrogen, phosphorus, and potassium are most common. Shortages of micronutrients are less common and tend to occur in certain geographic regions because of differences in soil composition. The symptoms of a mineral deficiency are often distinctive enough for a plant physiologist or farmer to diagnose its cause

7. Magnesium deficiency Symptoms chlorosis = yellowing of leaves
Why? What is magnesium’s function?

8. 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

9. organic matter 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

10. Fertilizers “Organic” fertilizers “Chemical” fertilizers
manure, compost, fishmeal
“Chemical” fertilizers
commercially manufactured
N-P-K (ex )
15% nitrogen
10% phosphorus
5% potassium