SALT INJURY from Problematic soils and water

SALT INJURY Soil science

1. Submitted by G.KAVIYARASAN I M.Sc.(Ag.) Soil Science ID.NO.: 2021520008 TNAU, Coimbatore. Submitted to Dr. D. Jegadeeswari Associate Professor Dept. of SS&AC TNAU, Coimbatore Topic : “SALT INJURY” SAC 510 MANAGEMENT OF PROBLEMATIC SOILS AND WATER

2. INTRODUCTION Salinity potential problem – Semi-arid and Arid regions Some soluble salts – N eed for Crop Production Saline condition drastically change Environment of root aeration, Osmotic potential of soil solution, Normal equilibrium of dissolved ions. Common effects – Growth suppression – crop yield reduction

3. SALT INJURY Levitt(1980) Three types of salt injury in plants Primary direct salt injury, Primary indirect salt injury, Secondary salt induced injury.

4. PRIMARY DIRECT SALT INJURY Very sudden – Salt Shock. Identified by Speed of action. Even most Halophytes, sensitive to direct sudden salt injury. Only species Salicornia – survive in High & Sudden Salt conc . @ root Medium. Too sudden to osmotic or secondary salt injury. Occurs even under Laboratory condition.

5. Primary Direct Salt Injury Effects Vacuole contraction & protoplasm swelling – death in few hours Increase impermeability & affects plasma membrane i.e. Tonoplast & plasmalemma / Cell membrane Change in protein & liquid composition of membranes. In Beans & Barley, Strong efflux of K+ due to alleviation by Ca will increase permeability .

6. Effects Induced High E lectro Conductivity :– S hunting of ions, Transport mechanisms Interference, Ultimate leakiness of membranes, Disruption, Rupturing & finally death

7. Primary Indirect Salt Injury The salt injury which is induced by disturbances in the metabolic machinery of the plant is called Primary Indirect Salt Injury Plant – State of equilibrium – environment – survive @normal condition – low ion conc. – must increase ion conc. Well balanced ions – @Protoplasm – for Normal functioning. Under salt stress/Unbalanced – Continuous Expenditure of Energy To balance Excessive ions( Na,Cl,SO4...,)

8. Primary Indirect Salt Injury affects Inhibition in Growth & Development – Decreases in Plant height Tiller number Leaf area(Cell division) Leaf/Cell elongation Leaf number 6. Other yield attributes..., Also Delay Flower emergence Early ripening of fruits(peach) Senescence(Beans & Cotton)

9. SECONDARY SALT INDUCED INJURY Osmotic stress injury(injury due to osmotic effects) Specific ion effects(Ion excess stress) Deficiency stress or Nutritional imbalance injury

10. I. Osmotic Stress Injury Reduced growth – Lack of Water – shortage within plants - even grown under moist soil comdition. Higher soluble salts – low osmotic potential of soil water - Prevent uptake of water by plants. Salts – Decrease water potential – reduces turgor – inhibits Growth, Development, elongation and enlargement of plants. Less height due to osmotic effect.

11. II. Specific Ion Effects(Ion Excess Stress) Iso-osmotic concentration of PEG & NaCl / NaSo4 – induce both osmotic as well as ionic effects @ equimolar concentrations. Effects occur on some legumes & cereals due to NaCl & NaSo4 than PEG Due to Cl- & SO4- ions This is called SPECIFIC ION EFFECT. This higher salt stress led to 1.Stomatal closure & 2.Decrease transpiration & 3. Defoliation & 4. Finally reduction in growth, yield & Dry matter accumulation.

12. III.Deficiency stress or Nutritional imbalance injury Saline soils – Low nutrient ion activities & Extreme ratio of Na+/Ca2+, Na+/K+,Ca2+/Mg2+,Cl-/NO3- in Soil Sol. Glycophytes @saline condition – Nutrient disorders. Vary based on Crops, Species, Cultivars, Intensity .

13. Effects Induces effects like 1. Decreased Macro- & Micro- nutrients. 2.Uptake & Partioning of nutrients within plants. 3. Physiological inactivation. 4. Growth inhibition – affects respiration of roots – uptake of essential nutrients decreased.

14. Low water potential of environment Salt accumulation in environment Low water potentials in plants Na salt uptake by plant Organic solute accumulation No extra solute accumulation Low turgor dehydration Low water potentials Osmotic adjustment High turgor & Hydration Low water potentials Salt uptake by plants Salt uptake by cells “Toxic Effects” Salt accumulations In cell walls Individual cells Have low turgor Dehydration and Low water potentials Toxic effects on enzymes, organelles and membrances Compartmentation o f ions into vacuoles: and cytoplasm is Salt free