Interactions between hydrostatic pressure and oxygen concentration on the germination of lettuce seeds.

Lettuce seeds were germinated at different hydrostatic pressures and O(2) concentrations. Some combinations of pressure and O(2) concentration stimulated while others retarded germination. The highest germination rates which occurred with pressure application and added O(2) were equalled at atmospheric pressure if the O(2) concentration was increased sufficiently. Increasing pressure generally retarded germination, but the pressure effect was partly offset by added O(2). Sustained pressures affected subsequent germination after pressure was released, but only when O(2) was present. Seeds to which pressure was applied in the absence of O(2) germinated as well after pressure exposure as untreated seeds.