Comparing dormancy breaking treatments in Parkinsonia aculeata seeds

Parkinsonia aculeata is a valuable medicinal plant in traditional medicine that is more adapted to tropical and subtropical arid regions and planted as an ornamental plant. Since, seed germination of P. aculeata does not occur easily, the current research was performed to test different dormancy breaking treatments on germination characteristics of P. aculeata.

The studied treatments included scarification with sandpaper, H2SO4 (98%), KNO3 (0.2%), soaking the seeds in 90 °C hot water for 15 minutes, Gibberellic acid (250, 500 and 100 ppm), leaching (placing the seeds in running water for 48 hours), combination of leaching treatment with KNO3, and combination of leaching treatment with Gibberellic acid (250, 500 and 100 ppm). To compare the results, distilled water was considered as control treatment. A Completely Randomized Design (CRD) was made with 13 treatments and 4 replications.

Results showed that there were significant differences between treatments on germination percent, germination speed, length of root, length of shoot and length of seedling and index of seed vigor (p<0.01). The seeds had more than 85% dormancy and applying leaching (germination percent, 75%) and scarification treatments (70%) as well as boiling water (57.5%) had the highest effect on releasing the seed dormancy compared to control (15%).

Since, one of the establishment problems of this plant is the seed dormancy period, using leaching for 48 hours will help in germination improvement of P. aculeata.