A. Hadas

D. Russo

Imbibition and seed germination as affected by water potentials, hydraulic conductivity, and seed-water contact area were studied. Water potential effects were studied under perfect seed contact and unlimited hydraulic con· ductivity. Effects on imbibition and germination of hy· draulic conductivity and seed-water contact were studied in an experimental setup in which separation between these factors was made possible while a very high water potential was maintained. The results show that low values of external water potential affect the rate of water uptake but not percent of germination. The rate of germination, however, is affected as long as water po· tential is higher than a critical value that is speciesspecific. For a given seed-water contact area, any de· crease in the hydraulic conductivity (or for a given con- ductivity, any reduction in contact area) reduced rates of water uptake and germination; total germination was not affected as long as the critical water potential was not reached.