Water Uptake and Response to Water Stress PDF

Water uptake and response to water stress • Chapter 3 (figure 3.9) • Chapter 4. Water balance of plants • Taiz and Zeiger (5th edition) 1 kg food = 1000 kg H2O examples illustrating the concept of water potential and its components: pressure potential & solute potential • Pure water has a Highe...

Water uptake and response to water stress • Chapter 3 (figure 3.9) • Chapter 4. Water balance of plants • Taiz and Zeiger (5th edition) 1 kg food = 1000 kg H2O examples illustrating the concept of water potential and its components: pressure potential & solute potential • Pure water has a Higher water potential Than 0.1 M sucrose solution examples illustrating the concept of water potential and its components (Part 2) In a faccid cell, there is no turgor pressure. Water potential of a flaccid cell In a turgid cell without sign of plasmolysis, there is turgor pressure (pressure potential) and solute potential: Water potential of 0.1 M sucrose solution= -0.244 MPa examples illustrating the concept of water potential and its components: pressure potential & solute potential Direction of water movement between 2 solutions? • higher water potential Solutions A: More water; higher water potential; less solutes: hypotonic Separated by a membrane Lower water potential Solution B: Less free water, Lower water potential; more solutes; Hypertonic Learning objective: Which way would water flow? (what is the principle) examples illustrating the concept of water potential and its components: pressure potential & solute potential If two solutions • More water, less solutes: hypotonic Separated by a membrane Less free water,more solutes Hypertonic Water will move across the membrane from hypotonic to hypertonic solution From high water potential to lower water potential Water uptake into root cells (root hairs) Need to know: 1. Water potential in the soil solution, separated by the cell membrane 2. Water potential inside the root hair Learning objective: under what conditions, would soil solution move into the root cells? Need to know which solution has more solutes. Why? Applying the priniciple of water movement in the previous slide 4.3 Rate of water uptake at various positions along a pumpkin root (Part 1) 4.3 Rate of water uptake at various positions along a pumpkin root (Part 2) Pulling force Dissipated Maintained 4.4 Pathways for water uptake by the root 6.20 Tissue organization in roots (Part 2) 3.13 Water can cross plant membranes by diffusion Aquaporins Soil water deficit Lowering water potential Potential water stress to plants 26.2 Leaves of young cotton (Gossypium hirsutum) plants abscise in response to water stress Comparison of the growth of the roots of normal vs. ABAdeficient maize plants 26.4 Effects of water stress on photosynthesis and leaf expansion of sunflower 26.5 Relative effects of water stress on photosynthesis and translocation in sorghum 3.14 Water potential of plants under various growing conditions