Germination Requirements Vary in Wild Rubus Species

1. Germination Requirements Vary in Wild Rubus Species Sugae Wada1* and Barbara M. Reed2. 1 Oregon State University 2 USDA-ARS National Clonal Germplasm Repository, 33447 Peoria Rd, Corvallis, OR 97333-2521 AbstractTo better define the germination requirements of wild species we examined the effect of two scarification agents, concentrated sulfuric acid and sodium hypochlorite on the seed of 6 species preserved at the National Clonal Germplasm Repository (NCGR) collected worldwide. This study indicates that Rubus species vary in their germination requirements with R. hoffmeisterianus exhibiting low dormancy and R. occidentalis very deep dormancy, while the others had moderate dormancy. • Results & Discussion: • Fresh untreated R. caesius seed had 14.5% germination, but untreated seed of the other 5 species did not germinate. • R. occidentalis had poor germination with all treatments (<8%). • One month after sulfuric acid treatment and warm stratification, germination was 67% of R. hoffmeisterianus seeds; 4 % of R. coreanus,6% of R. georgicus, 12% of R. caesius and none of R. occidentalis and R. ursinus. • Most sulfuric acid scarified seed germinated by 6 months with a few more by 12 months. • Sodium hypochlorite scarified seed germinated poorly at 6 months, but significantly improved by 12 months. Despite the increased germination at 12 months, sodium hypochlorite scarification produced significantly less germination than sulfuric acid for 4 of the 6 genotypes. • Germination treatments following sulfuric acid scarification produced >50% germination for 5 of the 6 species (not R. occidentalis) by 6 months. Germination treatments following sodium hypochlorite scarification were dependent on genotype. • This study indicates that Rubus species vary in their germination requirements with R. hoffmeisterianus exhibiting low dormancy and R. occidentalis very deep dormancy, while the others had moderate dormancy. InstructionSeeds of blackberry and raspberry have a deep dormancy caused by one or more mechanisms. Rubus seeds are normally enclosed in a hard endocarp that is a major constraint for their germination. It produces potential problems in the fields of breeding and conservation. • Materials & Methods • Six wild species: R. ursinus Cham. & Schltdl., R. georgicus Focke, R. caesius L., R. hoffmeisterianus Kunth & C. D. Bouché, R. coreanus Miq., R. occidentalis L. • Fruits were collected from the research field in June-July, 2006. • Seed were extracted with pectinase, cleaned, air-dried and kept in ambient temperature at least for 5 months. • Scarification: concentrated sulfuric acid (98%+) and sodium hypochlorite(14%) • Stratification: 4 weeks warm (18 oC) followed 12 weeks cold (4 oC), • Incubator: 4 wks in condition of 15 0C (8 h in dark) /30 0C (16 h in light) • Germination treatment: presence of either DI water, GA3, KNO3+ GA3 or smoke gas • Fresh untreated seeds were set and went go through the same stratification process • 50 seeds per Petri dish of 6 with 4 replications: completely randomized block design