Chardakov Technique Plant Physiology UNI Incubating tissue in

Chardakov Technique Plant Physiology UNI

Incubating tissue in solution Save for later measurement Pre-incubation Incubation Post-incubation

Did solution change concentration? • Solutes stay the same • If water left or entered tissue – Water also entered or left solution – Solution becomes more dilute or more concentrated • Changes in density of solution – More dilute = less dense – More concentrated = more dense • Density change detects concentration change

Compare solution densities • Pre-incubation vs post-incubation • Denser solution sinks to bottom • Problem: both are clear Pre-incubation Post-incubation

Dye one solution so we can see it Suspend one drop Does the drop rise? stay? fall? Pre-incubation Dyed pre-incubation Post-incubation

Drop movement tells us • If solution density has changed • If solution concentration has changed • Whether water has been lost to tissue or gained from it • Whether WP was higher at the start in tissue or in the solution

If the drop doesn’t move? • • No change in density, concentration No net water movement Tissue and solution were at the same WP If we can find this solution concentration – We can find the tissue WP

Tissue Water Potential Measurements Plant Physiology UNI

Tissue in solution • Water movement? • 3 possibilities – Water moves into tissue – Water moves out of tissue – Water does not move (= moves equally in both directions) • Water always moves from higher to lower water potential (WP)

How could you tell? • What would happen to • The size of the tissue? – Water moving in, out or no net movement • The concentration of the solution? – Water moving in, out or no net movement • The stiffness of the cells? – Water moving in, out or no net movement • Let’s make some predictions…

If water moves into tissue • From higher to lower WP • Tissue must have lower WP than solution at start • 3 consequences – Tissue gets bigger – Solution gets more concentrated – Cells get more rigid

If water moves out of tissue • From higher to lower WP • Tissue must have higher WP than solution at start • 3 consequences – Tissue gets smaller – Solution gets less concentrated – Cells get less rigid

If no net water movement between tissue and solution • No movement of water = no difference in WP • Tissue must have same WP as solution at start • No changes – Tissue stays same size – Solution stays same concentration – Cells stay equally rigid

What did you get? • Tissue size? • Solution concentration change? • Cell (tissue) rigidity?