Plant Water Relations: Drought Adaptations and Cavitation

Drought

Prolonged low rainfall causing water shortages.

Water Deficit

Insufficient water availability for plants.

Drought Avoidance

Strategies to prevent water loss during drought.

Drought Escape

Strategies to complete life cycle before drought.

Drought Tolerance

Ability to withstand water deficits without damage.

Abscisic Acid (ABA)

Hormone that promotes stomatal closure during drought.

Water Potential (Ψ)

Measure of water's potential energy in plant cells.

Pressure Potential (Ψp)

Pressure exerted by water in plant cells.

Turgor Pressure

Pressure from water in cells maintaining rigidity.

Plasmolysis

Cell shrinkage due to water loss.

Soil Water Holding Capacity

Soil's ability to retain water for plant use.

Ecophysiological Limits

Maximum yield potential related to water supply.

Crop Growth Stages

Phases affected by timing of water deficits.

Yield Optimization

Maximizing crop yield per unit water applied.

Climatic Changes

Long-term shifts impacting ecosystems and agriculture.

Stomatal Closure

Reduction of gas exchange to conserve water.

Physiological Processes

Functions affected by water availability in plants.

Morphological Changes

Structural adaptations for drought tolerance.

Anatomical Changes

Internal modifications aiding in water retention.

Short-term Drought

Drought effects observed over hours to years.

Long-term Drought

Drought effects observed over decades to centuries.

Famine Risk

Potential food shortages due to prolonged drought.

Photosynthesis Uncoupling

Energy absorption without driving photosynthesis.

Reactive Oxygen Species (ROS)

Damaging molecules produced during stress.

Stomatal Closure

Prevents water loss during drought.

Xylem Cavitation

Air bubble formation disrupting water transport.

Abscisic Acid (ABA)

Hormone increasing under drought, causing stomatal closure.

Root-Shoot Signal

Communication from roots to leaves regarding water status.

Transpiration Rate

Rate of water loss through stomata.

Wilty Phenotype

Inability to close stomata, leading to wilting.

Leaf Water Potential

Indicator of water status in leaves.

Chemical Signal

Non-hydraulic signal triggering stomatal closure.

Split Root Experiment

Study design to assess root water effects.

Hydraulic Control

Stomatal response based on leaf turgor pressure.

Elastic Stress Response

Reversible recovery from moderate water stress.

Photosynthetic Area Reduction

Decrease in leaf size affecting photosynthesis.

Growth Stage Sensitivity

Vulnerability to drought varies by developmental stage.

Yield Responses

Impact of stress on crop productivity.

Drought Acclimation

Long-term plant adjustments to water scarcity.

Short-term Responses

Immediate physiological changes to drought.

Photosynthetic Pigments

Compounds involved in light absorption for photosynthesis.

Membrane Lipid Peroxidation

Damage to cell membranes due to oxidative stress.

Drought Stress Threshold

Water potential range for plant recovery.

Fruit Tree Sensitivity

Particularly vulnerable during flowering and fruit set.

Maize Tassel Formation

Critical growth stage sensitive to water stress.

Drought Resistance

Ability to survive water deficits through adaptations.

Hydrophytes

Plants thriving in consistently wet environments.

Mesophytes

Plants growing in areas with moderate water availability.

Xerophytes

Plants adapted to survive in arid conditions.

Acclimation

Temporary physiological changes due to environmental stress.

Adaptation

Genetic changes fixed over generations for survival.

Annual Plants

Complete life cycle in one growing season.

Perennial Plants

Live for multiple seasons, optimizing survival.

Escape Mechanism

Completing life cycle before drought onset.

Avoidance Mechanism

Adjusting growth based on water availability.

Rapid Phenological Development

Fast growth to produce seeds before drought.

Developmental Plasticity

Variable growth based on seasonal water availability.

Drought Deciduous Species

Plants shedding leaves during dry periods.

Photosynthesis Rate

Speed of converting light into chemical energy.

Transpiration Rate

Water loss through plant leaves during photosynthesis.

Leaf Area Ratio

Leaf area relative to plant biomass.

Assimilate Allocation

Distribution of nutrients to fruits and seeds.

Canopy Leaf Area

Total leaf surface area of a plant.

Water Deficit

Condition of insufficient water for plant needs.

Morphological Adaptations

Structural changes aiding in drought survival.

Biochemical Adaptations

Chemical changes enhancing drought resistance.

Environmental Pressure

Natural selection factors influencing plant evolution.

Drought Stress

Condition resulting from prolonged lack of water.

Drought-deciduous species

Plants that lose leaves during water scarcity.

Photosynthesis

Process converting light energy into chemical energy.

Transpiration

Water loss from plant leaves to atmosphere.

Dormancy

State of reduced metabolic activity during stress.

Water potential

Measure of water's ability to move in plants.

Fouqueria splendens

Ocotillo plant, sheds leaves multiple times yearly.

Canopy development lag

2-4 week delay after rains for full leaf growth.

Drought-tolerant evergreens

Plants that retain leaves and withstand dry conditions.

Water savers

Plants minimizing water loss to conserve moisture.

Water spenders

Plants optimizing water uptake to maintain hydration.

Hydraulic conductance

Efficiency of water transport in plant systems.

Rooting patterns

Plant root structures enhancing water absorption.

Stomata

Tiny openings on leaves for gas exchange.

Transpiration area

Surface area of leaves involved in water loss.

Trichomes

Hair-like structures increasing light reflectance on leaves.

Phreaphytes

Plants accessing deep groundwater for moisture.

Prosopsis

Mesquite plant with deep root system.

CAM plants

Plants opening stomata at night to reduce water loss.

Drought tolerance

Ability to withstand low tissue water content.

Osmotic adjustment

Process maintaining cell turgor under low water.

Compatible solutes

Non-toxic compounds stabilizing proteins during drought.

Cell turgor

Pressure within plant cells maintaining structural integrity.

Osmotic potential

Tendency of water to move into cells.

Cellular elasticity

Ability of cells to stretch and adapt.

Compatible solutes

Short-lived compounds aiding in drought tolerance.

Evergreen shrubs

Plants retaining leaves during dry winter periods.

Resurrection plants

Plants reviving after extreme desiccation.

Sclerophyllous leaves

Thick, small leaves with low photosynthesis.

Stomatal closure

Prevention of water loss by closing leaf pores.

Turgor loss

Loss of cell pressure due to water deficiency.

Dimorphic root systems

Roots with both deep and shallow structures.

Taproots

Deep roots accessing groundwater during dry seasons.