Promotive Effects of Organic Solvents and Kinetin on Dark Germination of Lettuce Seeds

Significant promotion in dark germination was observed when Grand Rapids lettuce (Lactuca sativa L.) seeds were soaked in acetone or dichloromethane, vacuum-dried, and imbibed at 25 C. Permeation of kinetin via these organic solvents further enhanced the dark germination. Those seeds that were affected by acetone and acetone-kinetin treatments and germinated in the dark escaped red-far red photocontrol of germination. Although abscisic acid was not detected in the organic solvent leachates, they did contain other inhibitory substances affecting lettuce seedling growth. In the light, acetone and acetone-kinetin treatments also enhanced the rate of germination and the increased germination by acetone-kinetin treatment was correlated with increased polyribosome formation. The possible mechanisms involved in promotion of lettuce seed germination by organic solvents and kinetin are discussed.