Effect of acid scarification and cold moist stratification on the germination of Cercis siliquastrum L. seeds

Dormancy in Cercis siliquastrum seeds is due to the hard, impermeable seed coat and inhibition by endosperm. The effects of acid scarification, cold moist stratification, and the combination of both on breaking dormancy and enhancing seed germination were evaluated. Seeds were scarified with concentrated (95%-97%) sulfuric acid for various times (0, 20, 40, and 60 min), followed by cold moist stratification for 0, 1, 2, 3, or 4 months. Unscarified seeds did not germinate whether they were stratified (up until 4 months) or not. Similarly, seeds that were scarified (20, 40, and 60 min) and then stratified for 0 or 1 month did not germinate or exhibited very low germination percentages. The interaction between acid scarification and cold stratification treatments significantly affected seed germination. Particularly, after a period of 2 months of cold stratification, increasing the duration of scarification (20 to 60 min) also increased the germination percentages (31% to 65%). High germination percentages equal to 94%, 88%, and 98% were attained after a period of 3 months of cold stratification for seeds that had been scarified for 20, 40, and 60 min, respectively. Longer periods of stratification (4 months) of seeds scarified for 20, 40, and 60 min reduced the germination percentages (81%, 68%, and 59%, respectively). This decrease was higher in seeds that were scarified for 60 min.