Effects of gibberellic acid and storage temperature on the germination of hawthorn seeds

This study investigated methods to overcome seed dormancy in Crataegus pseudoheterophylla Pojarkova seeds. Seeds with and without endocarps were treated with gibberellic acid (GA3) at different concentrations and four storage temperatures. Then they were stratified in an alternate temperature regime. The amount of absorbed water in seeds with endocarps was monitored by measuring the fresh weight of seeds for 0, 24, 48, 72, and 96 h of imbibition. The electrical conductivity (EC) and the percentage of water uptake by seeds stored for 12 months at laboratory temperature, in a refrigerator, in a freezer, and in freeze-thaw conditions were measured. The highest germination (59.7%) was recorded in seeds without endocarps treated with 3,000 mg.l-1 GA3 and stored either in a laboratory or a refrigerator (32.7-35.3%). All treatments of seeds without endocarps where GA3 was applied showed statistically higher percentages of germination than the control. Seeds with endocarps stored at refrigerator temperature imbibed water up to 44.3% with increasing imbibition periods, whereas the amount of seeds that absorbed water in freezer and freeze-thaw conditions was almost the same. The tests showed the highest EC during storage in the freezer, with the lowest water uptake and viability in seeds stored during the freeze-thaw process.