Comparison of Physical, Acid, and Hot Water Scarification on Combinational Dormancy in Eastern Redbud and Judas Tree Seeds

Eastern redbud and Judas tree seeds show combinational dormancy requiring a scarification treatment to permit imbibition followed by a stratification treatment to relieve physiological dormancy. Hot water scarification was investigated as an alternative to physical and acid scarification in physically dormant eastern redbud and Judas tree seeds. Hot water scarification was an effective treatment to initiate seed imbibition in both species, but there was a relationship between treatment temperature and duration on dormancy release and embryo viability and vigor. The minimum temperature to initiate greater than 50% imbibition was 70 and 50 o C in eastern redbud and Judas tree, respectively. Hot water scarification at 100ºC was very effective for physical dormancy release, but even brief exposure to 100ºC reduced embryo germination and growth potential compared to physical or acid stratification. The temperature and duration that provided the highest imbibition (~ 100%) and embryo viability (90–100%) in eastern redbud were 80ºC for 5 minutes and 70ºC for 15 minutes. For Judas tree, the best conditions for imbibition (~ 70–85%) and viability (> 80%) were 70ºC for 10 minutes and 60ºC for 10 or 15 minutes. It is suggested that these temperature and duration combinations be the initial treatments used to evaluate eastern redbud and Judas tree seed lots.