Seed Germination Response to Temperature, Cold Stratification Period, and Gibberellin Treatment in Spiraea fritschiana

Abstract

To improve the germination of Spiraea fritschiana seeds for mass propagation, we evaluated the effect of a range of temperatures, cold stratification periods, and gibberellic acid (GA₃) treatments on three germination characteristics. Final germination percentage (FGP) increased as the temperature for seed germination increased, up to 30°C, while the mean germination time (MGT) and the mean number of days to 30% germination (T 30 ) decreased when seeds were germinated at 25-30°C. The optimum germination temperature of S. fritschiana seeds is approximately 30°C considering FGP, MGT, and T 30 together. FGP increased with the duration of cold stratification up to a period of 6 weeks, but declined after 8 weeks of cold stratification, as prolonged cold stratification can induce dormancy with a resultant decline in germination. Pretreatment with 6-8 weeks of cold stratification or soaking seeds in distilled water or 500 mg · L -1 GA₃ for 24 h accelerated and increased the germination of S. fritschiana seeds, regardless of temperature. However, further study might be required to evaluate the effect of GA₃ concentrations lower than 500 mg · L -1 on the promotion of germination in S. fritschiana seeds.