Testing germination methods and survival for a rare endemic, Barton’s raspberry (Rubus bartonianus)

Abstract

Barton’s raspberry (Rubus bartonianus M. Peck [Rosaceae]) is a narrow endemic of Oregon and Idaho found in the middle sections of Hells Canyon along the Snake River and its tributaries. The global distribution has decreased by approximately 24%, so germination and propagation techniques need to be developed for reintroduction purposes. We test 4 scarification treatments (control/none, mechanical scarification, bleach, sulfuric acid) and 3 cold stratification treatments (60, 90, and 120 d) in combination to determine the most effective method to improve germination and survival of Barton’s raspberry. Germination and survival are relatively high for all treatments, with the exception of mechanical scarification. Most treatments (control, bleach, and sulfuric acid) had > 64% germination after 60 d in cold stratification, whereas the mechanical treatment was 35%. The longer stratification treatments increased germination rates to > 80% for the sulfuric acid treatment and > 73% for the bleach treatment. The control treatment remained > 60% in the longer stratification treatments, whereas the mechanical treatment was < 43%. The high rates of germination for the sulfuric acid and bleach treatments can improve germination and survival when attempting to grow Barton’s raspberry from seed for reintroduction in its historic range.