salt stress of plant

1. Stress Physiology
Section : 2 Salt stress

2. • Mechanism of salt injure
• 1. Physiological drought。
• 2. Single salt toxicity .Na+ and Cl-，SO4
－.
• 3. Metabolic damage：Ch1 and Rubisco↓，protein degradation↑,Pro↑，NH4
+
poison↑.
• 4.Salt can lower the water potential of the soil solution and reduce water uptake
• 5. Plants respond to salt stress by producing solutes tolerated at high
concentrations
• 6. This process keeps the water potential of cells more negative than that of the
soil solution

12. II. SALT TOLERANCE
Salt tolerance: Ability of plants to prevent ,reduce or
overcome injurious effects of soluble salts present in their
root zone
Salinity can be overcome by
1)Soil reclamation: costly ,time consuming & short lived
2) Resistant varieties: less costly, more effective, long lasting
but require longer period to develop.
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13. Characteristics of plants to salt :
Salt tolerance capacity differs from species to
species
Different plants show differential response to
salinity
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19. Classification of plants based on salt
tolerance
1. Highly tolerant crops:
Sugar beet, barley, cotton, date palm, asparagus.
2. Moderately tolerant:
Barley, rye, sorghum, wheat, safflower, Soya been
3. Moderately sensitive:
Rice, corn, foxtail millet, cow pea, peanut, sugar cane, tomato,
potato, radish, cabbage
4. Extremely sensitive:
Citrus, strawberry, melon, peas, carrot, okra, onion.
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20. Symptoms of plant to salt stress
Retardation of growth
Necrosis
Leaf abscission
Loss of turgor
Ultimate death of plant
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23. Mechanism of salt tolerance
1. Salt tolerance:
By accumulating salt, generally in their
cells or glands & roots.
Halophytes show tolerance by ion
accumulation mechanism
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24. 2. Salt avoidance:
By maintaining their cell salt concentration
unchanged either by water absorption (e.g. Rice,
chenopodiaceae) or by salt exclusion (e.g. tomato,
Soya bean, citrus, wheat grass)
Glycophytes (nonhalophytes) owe their resistance
primarily to avoidance e.g. barley
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