Rubus spp. seed germination and morphology

• Main Author: Peacock, Derek N.
• Other Authors: Hummer, Kim E., Doescher, Paul, Danielson, Rodger, Strik, Bernadine D., Horticulture, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Rubus > Seeds > Processing; Rubus > Seeds > Viability; Rubus chamaemorus
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/7m01bn831

Rubus spp. seeds have a thick protective endocarp and testa (seedcoat) that can restrict germination even under favorable conditions. The effect of pregermination treatments were studied in Rubus chamaemorus L., R. eustephanos Focke ex Diels, R. idaeus 'Amber' L., R. leucodermis Douglas ex Torrey & A. Gray, R. multibracteatus A. Leveille & Vaniot, R. parviflorus Nutt., and R. ursinus Cham. & Schldl. Scarifying agents such as, sulfuric acid (H₂SO₄), sodium hypochlorite (NaOCl), calcium hypochlorite (CaO₂Cl₂), driselase, liquid nitrogen (LN₂), and others, were used as pregermination treatments. Sulfuric acid significantly increased percent germination in most of the Rubus spp. tested. Sodium hypochlorite above 2.6% injured seedlings of several species whereas lower concentrations were effective for scarification without seedling injury. Driselase did not significantly increase percent germination. This may have been due to little or no scarification of the endocarp at the 1-3% concentration range used. Liquid nitrogen did not significantly increase percent germination, however, it did not reduce overall percent germination as compared to the control. No loss of viability of Rubus seeds was found even with repeated immersions in LN₂. Cryogenic storage may thus be an effective way for preservation of Rubus seeds. The recommended pregermination treatments for most of the Rubus species studied, ranked in order of effectiveness, were concentrated H₂SO₄ followed by a 1 % CaO₂Cl₂ solution with an excess of Ca(OH)₂, concentrated H₂SO₄, 0.5% NaOCl or 2.6% NaOCl if the particular Rubus species does not show a sensitivity to high concentrations of NaOCl, and no treatment.