MINERAL NUTRITION

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MINERAL NUTRITION STRESS TOLERANCE
Stress conditions
1. Cold stress 2. Drought stress/Water
logging (Water deficit high temp.) 3. Salt
stress 4. Deficiency stress
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5. Chemical stress/Pollution 6.
Photostress Over Stress Optimum
Under Stress
Water/Temperature/Ion/Gas
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1. Water stress
- Water deficit - Water logging
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Water Deficit (Plant response to ) - Stomata
close Pn , Tr - Cell Leaf
expansion - Cell Turgidity - ABA, Respiration,
Sugar, Proline - Ion toxicity (Salt stress)
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Effect of Mineral Nutrition
N - increase LAI, shoot/root ratio (Less
N - supply, ABA increase better WUE) P -
deficiency increase ABA by water
shortage faster than P - Sufficient
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K - Osmoregulation - Stomatal movement
- Turgidity Enzyme activity Na - Partly
replace K Indirect effect on salinity
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Waterlogged flooded soil
Anaerobic reduction process cause
1) disappearance of O2 2) NO3- reduced to NO2-
N2O N2 3) MnO Mn2
exchangable toxic 4) Fe2 Fe3
availability increase toxic
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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
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Symptom
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
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Tolerance
- O2 - supply from shoot - Diminish ethylene
formation
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MINERAL NUTRITION WATER BALANCE
Water balance water uptake
transpiration
1. Water Uptake affected by ion
concentration in soil solution root - Osmotic
Potential difference - Salt stress
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2. Transpiration - Stomatal movement K
translocate into guard cell - More K fertilizer
gt low transpiration, More proline
drought resistant
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2. Temperature Stress
- Q10 and enzyme activity - Membrane
permeability ion uptake
Cold temperature inactivation of membrane bound
enzyme, i.e. respiratory enzyme in MT
respiration
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cold temp. also disrupt water and ion uptake
activity of root Frost cell
dehydration protein denatured cell wall
cracked
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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
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3. Mineral Stress
- Over supply - salt stress - Deficiency
Nutrient efficiency - genetic control -
growth stage/rate - mycorrhiza - soil
condition (pH, ion concentration)
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Soil condition mineral stress
1. Acid mineral soil (pH lt 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 pH5.5
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Al - toxicity
- inhibition of cell division at root
apical meristem - interfier P - uptake (AlPO4) -
inhibit Mg - , Ca - uptake (ion competition)
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Mn - toxicity
- directly effect the shoot - inhibit Ca Mg
uptake
- Liming to increase pH - Foliar application
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2. Alkaline soil
pH gt 7 (Calcareous soil) CaCO3 N main growth
- limiting factor - Fe
Fe(OH)2, Fe(OH)3 - Zn - P
Mn B
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3. Saline Soil (Na, Cl-)
- high salt concentration - high osmotic
pressure - water deficit, ion excess - stomata
close - small leaves, low Pn
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- Respiration increase - less protein
synthesis - Na complete Ca2 - Cl- complete
NO3-/P synergized
The end