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Prepared by Dr. M. Serdal SAKÇALI

D I FFERENT STRATEG I ES FOR WATER AVAILABILITY I N FOUR MED I TERRANEAN SCLEROPHYLLOUS PLANTS ( Ceratonia siliqua, Olea oleaster, Pistacia terebinthus and Quercus coccifera ) GROWİNG ON HEALTHY AND DEGRADED AREA. Prepared by Dr. M. Serdal SAKÇALI.

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Prepared by Dr. M. Serdal SAKÇALI

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  1. DIFFERENT STRATEGIES FOR WATER AVAILABILITY IN FOUR MEDITERRANEAN SCLEROPHYLLOUS PLANTS (Ceratonia siliqua, Olea oleaster, Pistacia terebinthus and Quercus coccifera) GROWİNG ON HEALTHY AND DEGRADED AREA Prepared by Dr. M. Serdal SAKÇALI The present study was funded by EU in the frame of the project entitled: "Desertification in Mediterranean Drylands: Development of a monitoring System based on Plant Ecophysiology(DEMOS, Contract no:IC18-CT97-0153).

  2. Environmental Problems; • pollution • poor management • population pressure • degradation • desertification, • global warming, • ozone depletion, • climatic changes, excessive erosion, decreasing biodiversity, melting of glaciers, ………..

  3. Water and Plants • Plants are typically about 90% water. • A typical crop or grassland will transpire about 500 kg of water per kg dry wt. produced. • Water transports inorganic nutrients and photosynthetic products to various parts of the plant. • Water is also the electron donor for photosynthesis. • Water evapotranspiration also keeps plants from overheating.

  4. Movement Direction of Water in Plant

  5. Transpiration • Stomatal pores in leaves open to allow movement of carbon dioxide in leaf for photosynthesis • Water vapor is lost through pores by transpiration • Loss of water from non pore areas is restricted by a waxy impermeable cuticle

  6. Transpiration of Some Plants

  7. Stomatal control • When water stressed, plants increase thickness of cuticle • In light, guard cells accumulate potassium ions and organic acids • This decreases their osmotic pressure which causes them to fill with water and enlarge the stomatal pores • Extra water losses will cause the cells and pores to shrink, reducing water loss • Under conditions of water stress, leaves produce a hormone, abscisic acid, which promotes stomata closure • Stomatal pore size can also be regulated by CO2concentration

  8. Stomatal Opening Conditions favouring Conditions favouring closing opening Lack of water Abundant water Darkness Abundant Light High internal CO2 Low internal CO2 Presence of ABA High humidity

  9. Absorption • Absorption refers to uptake of water by roots to compensate for water losses by transpiration • During daylight, transpiration exceeds absorption and cells shrink lowering their water potential • At night, stomatal pores close and water potential of leaves becomes restored.

  10. Water Potential • The movement of water in osmosis involves both diffusion and mass flow • The free energy gradient of water • chemical potential of water • The major components of water potential are turgor pressure and osmotic potential

  11. Ψ= ΨP+Ψπ+qghΨP= Turgor pressure Ψπ= Osmotic potential q=Density g=Gravity h=Altitude ΨP= The pressure of water pushing against the inside of the cell wall Ψπ= -CRT C= Molar concentration of solute (moles/L) R= Gas constant (8.31 m3 Pa mole K-1) T= Temperature (0K) Ψπ of; Sea water =2.49 Mpa Plant cell sap =0.73 MPa

  12. Summary of Factors Influencing water potential

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