Abiotic Stress - Effect Of Drought On Plants

PLANT RESPONSE TO DROUGHT

-Sindhuja

Presentation Outline • Introduction • Discussion • • • • •

Desiccation Stomata location & function Adaptations in Xerophytes Leads to abscission Acclimatization

• Conclusion • References

INTRODUCTION • Plants do photosynthesis • need – Water, Carbon-dioxide and sunlight • Water – is one of the 3 main factors

• Water evaporated = water absorbed • If not – there will be lack of water • Leads to drought

GROWTH AND DEVELOPMENT • For any plant to undergo growth and development , the basic step involved is – cell enlargement and – cell division.

• For this cell enlargement and cell division, the basic step involved is – turgor pressure – caused due to water

INTRODUCTION • What is drought? • no sufficient water in the soil • for the crop to grow • Extended usually for several months

• How do plants overcome drought • Adaptation • Acclimatization

DISCUSSION

DESICCATION • Homo-chlorophylous desiccation tolerant • PA - elastic • Poikilo-chlorophylous desiccation tolerant •PA - degraded

STOMATA

LOCATION OF STOMATA • Adaxial surface – upper epidermal layer • few number of stomata

• Abaxial surface – lower epidermal layer • many number of stomata

LOCATION OF STOMATA

ADAPTATION IN XEROPHYTES What are Xerophytes? Plants which are able to survive in an environment with little available water or moisture, usually in environments where potential evapotranspiration exceeds precipitation for all or part of the growing season.

XEROPHYTES • Thick leathery cuticle

• Reduced size of leaves

XEROPHYTES • Leaves modified into spines

• Water storage in stem

CHANGES IN GENE EXPRESSION • A stress response is initiated when plants recognize stress at the cellular level • Stress recognition activates signal transduction pathways that transmit information within the individual cell and throughout the plant.

Water deficit stimulates leaf abscission

ACCLIMATIZATION What is acclimatization? A process in which a plant undergoes changes to suit to the environment for a period of time usually often involving temperature, moisture, food, often relating to seasonal climate changes

ACCLIMATIZATION • Paraheliotropic

• Diaheliotropic

CONCLUSION Plants adapt to various mechanisms…. in order to get rid of the stress caused. It is really appreciatable to see these plants seem to have sense to sense the lack of water and compensate them by adaptations.

MAIN REFERENCES •Bewley, D.A. , 1979. Physiological aspects of desiccation tolerance. Annu. Rev. Plant Physiol. •Gounaris, K., Brain, A. P. R., Quinn, P. J.,W. P. Williams, 1984. Structural reorganization of chloroplast thylakoid membranes in responseto heat stress •Marschner H (1995) 'Mineral nutrition of higher plants.' (Academic Press: London.)

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