Pregermination studies with liquid nitrogen and sulfuric acid on several Rubus species

Abstract

We contrasted the effect of liquid nitrogen (LN2), sulfuric acid (H2SO4), and a nontreated control on the germination of six Rubus species. We also were interested in determining if LN2 could be an effective mechanical scarifying agent for these species. Seeds of each species were treated with three 3-minute dips in LN2 with alternating 10-minute thaws, with H2SO4 for 30 minutes, or left untreated. The percent germination of R. multibracteatus A. Leveille & Vaniot, R. parviflorus Nutt., R. eustephanos Focke ex Diels, R. leucodermis Douglas ex Torrey & A. Gray, R. ursinus Cham. & Schldl., and R. chamaemorus L. treated with LN2 was not significantly different than the control. Germinated seedlings from the LN2 treatment of each species showed normal development upon planting, indicating that long-term cryogenic preservation of these Rubus species seeds may be possible. The H2SO4 treatment significantly increased the rate and percentage of germination in R. parviflorus, R. eustephanos, R. leucodermis, and R. ursinus over that of the control and the LN2 treatment. The alternative LN2 application techniques that have been attempted thus far have not significantly improved Rubus seed germination compared with that of the control.