Mineral Nutrition & Nutrient Uptake by Plants

Plants and Inorganic Nutrients

17 essential plant nutrients ? In its absence plant is unable to complete

normal life cycle ? Element is part of some essential plant

constituent or metabolite ? Element cannot be replaced by other element ? Deficiency cannot be corrected by the

addition of similar elements of factors.

Essential Plant Nutrients

Element

Chem. Available form

Macronutrients Symbol

Hydrogen

H

Carbon

C

Oxygen

O

Nitrogen

N

Potassium

K

Calcium

Ca

Magnesium

Mg

Phosphorus

P

Sulfur

S

H2O CO2 O2, CO2 NO3-, NH4+ K+

Ca2+

Mg2+

H2PO4-, HPO42SO42-

Conc. in DM mmol/kg

60,000 40,000 30,000

1,000 250 125 80 60 30

crop physiology / summer semester

Mineral Nutrition & Nutrient Uptake by Plants

Nutrient Roles in Plants

Role Constituents in plant structure Constituents of proteins, enzymes, nucleic acids Inorganic nutrient involved in metabolic energy transfers Constituent of chlorophyll Constituents of stored energy in seeds, fruits, tubers, etc Terminal electron acceptor in respiratory energy exchange Involved in maintenance of ionic balance Constituent of cytochromes, ferrodoxin Involved in water splitting in photosynthesis Involved in sugar metabolism and transport Constituent of nitrogen reducing enzymes Other essential elements involved in enzyme reactions

Element C, H, O, Ca N, S, C, H, O, P P Mg C, H, O O

K Fe Mn, Cl B Mo Cu, Zn, Mn, Zn, Fe

1

Beneficial Elements

? Sodium - Na, required for C4 plants, perhaps pyruvate transport

? Silicon - Si, strengthens cell wall in grasses, helps fight fungi, lodging

? Cobalt - Co, essential for legumes, really for N2-fixing bacteria

? Selenium - unknown role

What is the critical concentration?

? A tissue concentration below which growth is limited by 10%.

? A toxic concentration can be defined as the concentration above which growth is limited.

? Nutrient concentrations in between critical and toxic are termed adequate.

crop physiology / summer semester

Essential Plant Nutrients

Element

Chem.

Micronutrients Symbol

Chlorine

Cl

Boron

BO

Iron

Fe

Manganese Mn

Zinc

Zn

Copper

Cu

Nickel

Ni

Molybdenum Mo

Available form

ClBO33Fe2+, Fe3+ Mn2+ ZN2+ Cu2+ Ni2+ MO42-

Conc. in DM mmol/kg 3.0 2.0 2.0 1.0 0.3 0.1 0.05 0.001

Critical Concentration of Nutrients

2

Soil Water and Minerals

pH and Mineral Nutrient Availability

crop physiology / summer semester

Nutrient Uptake from Soil

? Interception --contact exchange between root surface and soil particles

? Mass flow --nutrients in solution move to root surface along a water potential gradient

? Diffusion -- nutrients move down a concentration gradient from areas of high to lower conc.

Factors Affecting Mineral Nutrient Availability

? Soil moisture ? Organic matter ? Soil texture ? Soil temperature ? Soil pH

3

Hydroponic and aeroponic systems for growing plants in nutrient solutions in which composition and pH can be automatically controlled. (A) In a hydroponic system, the roots are immersed in the nutrient solution, and air is bubbled through the solution. (B) An alternative hydroponic system, often used in commercial production, is the nutrient film growth system, in which the nutrient solution is pumped as a thin film down a shallow trough surrounding the plant roots. In this system the composition and pH of the nutrient solution can be controlled automatically. (C) In the aeroponic system, the roots are suspended over the nutrient solution, which is whipped into a mist by a motor-driven rotor.

Lab slide

Hydroponic Culture and Essential Elements

Lab slide

crop physiology / summer semester

Lab slide

4

Hydroponic Farming

Lab slide

Nutrient deficiencies

? Mineral nutrient deficiencies occur when the concentration of a nutrient decreases below the critical deficiency content (CDC)

? Mineral nutrient deficiencies are another conceptual example of the "Law of the minimum"

? Nutrient deficiency and CDC values determined from a variety of studies

? Greenhouse ? Hydroponic

Lab slide

crop physiology / summer semester

Lab slide

Lab slide

5

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download