Evaluation of Germination Promoting Treatments for Toxicodendron vernicifluum Seeds Based on Breaking Physical and Physiological Seed Dormancy.

Abstract

The seeds of Toxicodendron vernicifluum are considered to be in a state of combinational dormancy, which is a combination of physical and physiological dormancy. To improve the germination rate of T. vernicifluum seeds, the methods reported to be effective in promoting seed germination were evaluated separately for breaking physical and physiological seed dormancy. The most effective methods for breaking physical dormancy of T. vernicifluum seeds were soaking in concentrated sulfuric acid (H2SO4) for 60 to 120 min or partial removal of the endocarp. Water absorption was observed to begin at two locations on the seed after soaking in H2SO4 for 90 min. Cold stratification for 4 to 12 weeks was effective in breaking physiological dormancy of the seeds after soaking in H2SO4. However, seeds treated with cold stratification after partial removal of endocarp did not germinate. The germination rate of seeds soaked in H2 SO4 for 90 min followed by 8 weeks of cold stratification (73.2±2.7％）was significantly higher than that of seeds soaked in H2SO4 or cold stratification alone (0.8±1.0％ and 0.4±0.9％, respectively) or no treatment (0.0±0.0), indicating that the combined treatment would be effective for improving T. vernicifluum germination.