Dry seeds when placed in water swell up due to

Dry seeds when placed in water swell up due to Imbibition.
Imbibition is a special type of diffusion that takes place when liquid is absorbed by solids-colloids causing an increase in volume.
Water surface potential movement takes place along a concentration gradient; some dry materials absorb water. A gradient between the absorbent and the liquid is essential for imbibition.