MINERAL NUTRITION & MINERAL NUTRITION & STRESS TOLERANCESTRESS TOLERANCE

Stress conditions :

1. Cold stress

2. Drought stress/Water logging

(Water deficit + high temp.)

3. Salt stress

4. Deficiency stress

5. Chemical stress/Pollution

6. Photostress

Over = Stress

Optimum

Under = Stress

* Water/Temperature/Ion/Gas

1. 1. Water stressWater stress

- Water deficit

- Water logging

Water DeficitWater Deficit (Plant response to :) (Plant response to :)

- Stomata close Pn , Tr

- Cell & Leaf expansion

- Cell Turgidity

- ABA, Respiration, Sugar, Proline

- Ion toxicity (Salt stress)

N - increase LAI, shoot/root ratio

(Less N - supply, ABA increase better WUE)

P - deficiency increase ABA by water

shortage faster than P - Sufficient

Effect of Mineral Nutrition

K - Osmoregulation

- Stomatal movement

- Turgidity & Enzyme activity

Na+ - Partly replace K+

Indirect effect on salinity

Waterlogged & flooded soilWaterlogged & flooded soil

1) disappearance of O2

2) NO3- reduced to NO2

- N2O N2

3) MnO Mn2+ exchangable & toxic

4) Fe2+ Fe3+ availability increase & toxic

Anaerobic & reduction process cause :

5) increase P solubility

6) SO4= H2S decrease solubility of

Fe, Cu, Zn, Cd

7) ethylene , volatile fatty acid & phenolics

compound accumulate from decomposable

organic manure

SymptomSymptom

1. Wilting (ethylene accumulation decrease of

water permeability of root)

2. Lower leaf senescence (N - deficiency)

3. Lowering nutrient uptake Nutrient

deficiency

4. Inhibit Cyt. & GA synthesis and transport

but promote ethylene synthesis in leaves

5. Acetaldehyde & ethanol formation - Toxins

Tolerance :Tolerance :

- O2 - supply from shoot

- Diminish ethylene formation

MINERAL NUTRITION & WATER BALANCEMINERAL NUTRITION & WATER BALANCE

Water balance = water uptake

transpiration

1. Water Uptake

affected by ion concentration in soil solution & root

- Osmotic Potential difference

- Salt stress

2. Transpiration2. Transpiration

- Stomatal movement & K+ translocate into guard cell

- More K fertilizer => low transpiration,

More proline drought resistant

2. 2. Temperature StressTemperature Stress

- Q10 and enzyme activity

- Membrane permeability & ion uptake

Cold temperature : inactivation of membrane bound enzyme, i.e. respiratory enzyme in MT respiration

cold temp. also disrupt water and ion uptake activity of root

Frost cell dehydration

protein denatured

cell wall cracked

High temperature

- Commonly combine with water stress

(high transpiration rate)

- PS = the most temperature sensitive

(Chloroplast, Enzyme, Membrane) PS ll

- Tolerance = Chloroplast, PS ll, Protein

Stability

3. 3. Mineral StressMineral Stress

- Over supply - salt stress

- Deficiency

Nutrient efficiency :

- genetic control

- growth stage/rate

- mycorrhiza

- soil condition (pH, ion concentration)

Soil condition & mineral stressSoil condition & mineral stress

1. Acid mineral soil (pH < 4)

- excess Al & Mn

- deficiency of P Ca & Mg

- some cases low S K Mo Zn Cu

Al - toxicity = main limiting factor for growth until pH~5.5

Al - toxicity

- inhibition of cell division at root

apical meristem

- interfier P - uptake (AlPO4)

- inhibit Mg - , Ca - uptake (ion competition)

Mn - toxicityMn - toxicity

- directly effect the shoot

- inhibit Ca & Mg uptake

- Liming to increase pH

- Foliar application

2. 2. Alkaline soilAlkaline soil

pH > 7 (Calcareous soil)

CaCO3

N = main growth - limiting factor

- Fe Fe(OH)2+, Fe(OH)3

- Zn

- P Mn B

3. 3. Saline Soil Saline Soil (Na(Na++, Cl, Cl--))

- high salt concentration

- high osmotic pressure

- water deficit, ion excess

- stomata close

- small leaves, low Pn

- Respiration increase

- less protein synthesis

- Na+ complete Ca2+

- Cl- complete NO3-/P synergized

The end