Determination of uptake of water by swelling seeds by seed imbibition experiment when placed in sodium chloride solution of different concentrations.
Objective of Seed Imbibition Experiment
This experiment is performed to demonstrate the phenomena of imbibition as a method used by the plants to acquire water, especially in seed germination.
Imbibition is a special type of diffusion in which net movement of liquid is along a diffusion gradient. In it instead of absorption (as in diffusion), adsorption takes place.
Imbibition is governed by two conditions.
(1) Potential gradient must exist between the surface of the adsorbent and the liquid imbibed.
(2) Certain affinity must exist between components of the adsorbent (gram seed) and the imbibed substance (Water).
Apparatus/Chemicals for Seed Imbibition Experiment
Oven dry gram seeds, Sodium chloride, five reagent bottles of 250ml, distilled water analytical balance, graduated cylinder.
Procedure of Seed Imbibition Experiment
Molecular weight of NaCl is 23 + 35.5 = 58.5. Prepare 4M, 2M, 1M and 0.5 molar solutions of sodium chloride in distilled water. Take clean, washed and dried reagent bottles, and pour 100 ml of solution in each stoppered bottle. Weight five samples of seeds approximately 5 grams (up to 2 digits) and add each sample to each reagent bottle. Fifth bottle should contain 100 ml of distilled water. Label the bottles and leave them as such.
After 48 hours take out the seeds separately and re-weight (up to 2 digits) them after gently blotting and record the readings in the given table.
Plot a curve showing grams of water taken per gram of seeds as ordinate and osmotic pressure of solutions as abscissa.
(The approximate osmotic pressure of NaCl at 4M, 2M, 1M, and 0.5M are 130, 72, 38 and 19 atmosphere respectively.
|Solution of NaCl||Initial weight of the seeds||weight of the seeds||Amount of water taken up by seeds||Water taken up per gram of seeds|
1 M, NaCl
2 M, NaCl
4 M, NaCl
Precautions of Seed Imbibition Experiment
1) Stoppered bottles should be used to check any vapor loss which could alter the solution concentration.
2) Carefully weight and prepare different Molar solutions of NaCl.
3) Seeds should be oven dry at 103°C for two hours before use.
(The osmotic pressure of NaCl at 4M, 2M, 1M and 0.5M is 130, 72, 38 and 19 atmospheric respectively).