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In Vitro Germination and Dormancy Responses of Hydrangea macrophylla and Hydrangea paniculata Seeds to Ethyl Methane Sulfonate and Cold Treatment

Greer, Stephen Patrick, Rinehart, Timothy A.
HortScience 2009 v.44 no.3 pp. 764
Hydrangea macrophylla, Hydrangea paniculata, seed germination, dormancy breaking, seed stratification, plant breeding, mutagenesis, cold storage, alkylation agents, 2,3,5-triphenyltetrazolium chloride, ethyl methanesulfonate, dose response, viability, cultivars, genetic variation
To determine the optimal conditions for mutagenesis of Hydrangea macrophylla (Thunb.) Ser. and Hydrangea paniculata Siebold, cold-treated and untreated seed from representative cultivars were exposed to 0.5%, 2.5%, and 5.0% ethyl methane sulfonate (EMS). Most untreated H. macrophylla seed exposed to 2.5% and 5.0% EMS had substantially lower germination percentages. H. paniculata seed germination percentages did not differ from controls until EMS concentrations reached 5.0%. Cold treatment of H. macrophylla and H. paniculata seed made germination more tolerant to all concentrations of EMS tested and increased germination of most H. macrophylla cultivars when compared with lower dosages. Germination of cold-treated seed from H. paniculata cultivars rose substantially above control levels even at the highest dosages. For the most part, we observed more nondormant seed, or seed available for germination, but less viability with increasing EMS dosage in untreated Hydrangea L. seed versus controls. In contrast, cold-treated seed displayed higher levels of mutagen tolerance and nondormancy versus controls when exposed to these same doses of EMS.