Proposed Method for Measuring Swelling Pressure of Seeds prior to Germination

A method for the indirect measurement of swelling pressure of seeds is proposed on the basis of volume change—gravimetric water-content relationship. In clay soils, change in volume is exactly equal to change in water content. As a result the force of water retention is exactly equal to the swelling pressure. Studies with rapeseed, wheat, and corn showed that change in volume was equal to, or greater than, the change in water content. On the basis of this result it was assumed that swelling forces were equal to forces of water retention. Therefore the swelling pressure could be estimated from a knowledge of water retention properties of the seed. According to the method proposed, swelling pressure of air-dry seeds is of the order of 4000 bar. As seeds absorb water the swelling pressure of seeds decreases rapidly and is approximately 10–20 bar just before germination.