Water in Plant Life

Flashcards about plant water relations

What is Poikilohydric?

Water content and flow depends on ambient water conditions, tolerance to desiccation, poor water retention, found in cell communities and unicellular organisms.

What is Homoiohydryc?

Tolerates major fluctuations in water conditions, does not tolerate desiccation, good water retention capacity, found in higher plants.

How are Homoiohydryc plants classified?

According to water conditions - In water (Hydrophytons and Helophitons) and On land (Higrophyton, Mesophyton, and Xerophytes).

What are Hydrophytons and Helophitons?

Aquatic and swamp plants with underdeveloped transport tissue, nutrient uptake from water, may be rootless, submerged or spread on the surface, may have stomata on the upper leaf surface.

What are Higrophyton and Mesophyton?

Moisture-loving and medium water availability plants, respectively. Higrophyton have well-watered soil and thin, large leaves. Mesophyton tolerate temporary drought and have developed stomatal regulation.

What are Xerophytes?

Drought-tolerant plants with various adaptations like thick leaves, succulents, large root surfaces, sunken stomata, thick cuticle, and leaves modified into spines.

How can water availability affect plant anatomy?

Root to leaf area ratio, cuticle thickness, and stomata characteristics (presence, position relative to epidermis) vary based on water availability.

What is RWC?

Relative Water Content, a measure of water content in plant tissues.

What is WSD?

Water Saturation Deficiency, difference between saturation and actual water content.

What is water potential?

Water potential is the sum of pressure potential and solute potential and dictates the direction of water movement.

What is the water potential gradient in plants?

0 > ψ soil > ψ root > ψ leaf, where ψ represents water potential.

What is the driving force for water movement in xylem?

Transpiration from leaves and negative water potential in roots.

How does sucrose transport work in phloem?

Active transport of sucrose into phloem decreases water potential, causing water to enter from xylem, and creates high pressure that drives bulk flow.

What is transpiration?

Evaporation of water from mesophyll cell walls in leaves.

How does transpiration occur?

Through stomata (stomatal) or through the cuticle (peristomatal), with stomatal transpiration being much greater.

How does stomata open and close?

By changes in guard cell turgor pressure (hydroactive opening/closing), influenced by light and other environmental factors (photoactive movement).

What happens when stomata opens?

water uptake, decrease W increase electrochemical gradient, ion uptake.

What happens when stomata closes?

release water, increase W, decrease electrochemical gradient, ion release.

What activates K-channels leading to stomatal closing?

A change in electrical charge and abscisic acid (ABA).

What influences stomata regulation?

Leaf water status, sunlight, CO2 in mesophyll cells, air temperature, soil water availability, transport efficiency, leaf transpiration, temperature, humidity, leaf physiology

What are some measurement tools used in plant studies?

Pressure in phloem, Micro-pressure probe, and Porometer.