Effect of scarification, GA and chilling on the germination of goldenrain-tree (Koelreuteria paniculata Laxm.) seeds

In contrast to scarified seeds, unscarified seed did not germinate in any of the treatments, indicating that Koelreuteria paniculata Laxm. seeds have hard, impermeable seed coat dormancy. Exogenous application of 100, 200 and 300 ppm GA increased germination of scarified seeds from 0 (control) to 17, 18 and 15%, respectively. Pre-chilling in distilled water (DW) for 60 days increased germination to 44%. Compared with DW-chilled seeds, the germination of seeds chilled in gibberellic acid (GA-chilled) was significantly increased after 15 days of chilling and maximum germination of seeds chilled in 100, 200 and 300 ppm GA was 60, 51 and 54%, respectively, achieved after 30 days. Longer duration of chilling in GA appeared harmful. Germination rate was positively correlated with germination percentage. These results show that K. paniculata seeds exhibit both exogenous and endogenous dormancy. A combination of GA and chilling (GA-chilling) helped to alleviate seed dormancy in a relatively short period of time. (C) 2000 Elsevier Science B.V. All rights reserved.