Saleque Salinity
Transcript of Saleque Salinity
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SALINITY MANAGEMENT IN
COASTAL SOILS
M A SALEQUE
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Outline
What is salinity?
Types of salinity.
Causes of salinity. Measurement of salinity.
How salinity causes harm to plants?
Adaptive mechanisms of plants to saline soils. How to manage saline soils?
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What is soil salinity?
Accumulation of salts in soils at a level higher
than 4 dS/m.
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Types of salinity
Inland salinity
Coastal salinity
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Inland salinity
Due to groundwater irrigation.
Due to natural salinity in landscape.
Industrial waste disposal.
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Coastal salinity
Salt water intrusion.
Flooding with saline tidal water.
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Coastal salinity
Sea floor (max
1340 m)
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Coastal salinity
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Coastal salinity
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Coastal salinity
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Measurement of salinity
Saturation extract
Field measurement
Caution calibration of machine
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Unit of salinity
Deci simen/m (dS/m)
ppm
ppt
1 dS/m = 670 ppm
1 dS/m = 0.67 ppt
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How salinity harms plant
Water stress due to osmotic effect
Toxicity from excess Na uptake
Imbalance Na/K and Na/Ca ratio. Leakage of K from cytoplasm.
Affect enzymatic activity that are mediated by
K.
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Symptoms of salt injury in rice plant
Stunted growth
Reduced number of tillers
Reduced root growth
Rolling of leaves Drying of leaves
White leaf tips
White blotches on the leaves
Sterile spikelets
Delayed flowering or no flowering at all.
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Symptoms of salt injury in rice plant
Stunted growth
Reduced number of tillers
Reduced root growth
Rolling of leaves Drying of leaves
White leaf tips
White blotches on the leaves
Sterile spikelets
Delayed flowering or no flowering at all.
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Symptoms of salt injury in rice plant
Stunted growth
Reduced number of tillers
Reduced root growth
Rolling of leaves Drying of leaves
White leaf tips
White blotches on the leaves
Sterile spikelets
Delayed flowering or no flowering at all.
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Symptoms at different salinity
EC
(dS/m)
Salinity
level
Symptoms
3.0 4.5 Medium
salinity
Nearly normal growth; some
reduction in tillering; someleaves are rolled.
5.0 8.5 High
salinity
Reduced growth and tillering;
most leaves are rolled; very
few are elongating
9.0 14.5 Very high
salinity
Growth completely ceased;
most leaves get dry and wither
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Sensitivity of rice plants to salinity at
different growth stages
Growth phase Growth stage Sensitivity
Vegetative Germination Tolerant
Seedling Sensitive
Tillering Tolerant
Stem elongation Tolerant
Reproductive Panicle initiation Sensitive
Flowering SensitiveHeading Sensitive
Ripening Milk grain Tolerant
Dough grain Tolerant
Mature grain Tolerant
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How salinity harms plant
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Irrigation water quality
Classes Quality EC (dS/m)
Class 1 Excellent 0.25
Class 2 Good 0.25 0.75
Class 3 Permissible (leaching needed ifused)
0.76 2.0
Class 4 Doubtful (good drainage needed
if used)
2.01 3.00
Class 5 Unsuitable 3.00
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Annual salinity trend
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Adaptive mechanisms of plants to
salinity
Osmotic adjustment by the accumulation ofhigh concentrations of either inorganic ions orlow molecular weight organic solutes.
Restricted uptake of Na ions exclusion effect.
Rapid vegetative growth dilution effect
Accumulation of salt in older leaves so that
young leaves can grow compartmentalization.
Maintaining high K/Na ratio.
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Management of coastal saline soils
Embankment to protect intrusion of saline
water.
Irrigation with non-saline water. Flushing with non-saline water.
Growing salt-tolerant variety.
Growing cover crops during rabi season. Gypsum application if soils pH > 8.5.