Acta Hort. (ISHS) 2015, 1064: 247-251.
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Abstract: Rumen Conev and Parminder Sandhu. Many landscape roses have poor and erratic seed germination which poses significant challenge to hybridizers. A series of multi-factorial replicated experiments have been conducted in Vineland, Canada since 2010 to study the effect of achene coat scarification, maceration, and warm and cold stratification on seed germination in garden roses. The response of 11 garden rose cultivars to six different seed treatments (T) was studied in 2010-2011. Morden Snow Beauty, Morden Sunrise and Carefree Spirit did not respond to any treatment. Six-week cold stratification alone (6WCS) (T1) did not induce germination in any genotype. Scarification with 50% sulphuric acid for 30 or 60 s followed by 6WCS (T2 and T3) slightly increased the germination in Parkwood Scarlet and Lupo. Adding three weeks warm stratification (3WWS) prior to the cold stratification (T4) provided modest benefit only to Morden Blush, which along with Cape Diamond had the highest germination response (31 and 16%, respectively) when sulphuric acid was replaced with 0.5% cellulase for 36 h (T5). The combination of extended exposure to warm and cold stratification 9WWS + 12WCS (T6) gave the best germination in 6 out of 11 genotypes (up to 52% in Lupo). In a second experiment conducted in 2011-2012, achenes from cultivar Morden Blush were subjected to nine scarification and maceration treatments followed by uniform stratification regime (5WWS + 15 WCS). Overall, the treatments involving achene coat maceration with cellulase resulted in significantly higher germination (32-49%) compared to the seed scarification treatments with sulfuric acid (15-17%). The treatment with 0.5% cellulase for 50 h gave the best germination.