Effects of various dormancy breaking treatment on seed germination in Sclerorhachis leptoclada boiss: an endangered medicinal plant in arid area

Abstract

The aim of this study was to investigate the effect of pre-sowing treatments and temperature on Sclerorhachis leptoclada Boiss. seed germination. The following treatments were used), hot water (soaking in water at 70?C and 90?C for 5 second), Moist Chilling (Soaking in water at 2?C for 7,14 and 21day with the temperature gradually falling to room temperature), scarification by 0.2% potassium nitrate (soaking for 24 h and 48 h) and Gibberellic acid (GA: at concentrations of 250, 500 and 750 ppm soaking for 24 h and 48 h) and Distilled Water (control). The percentage of germination, germination rate, germination start (GS), mean germination time (MGT), and germination vigor index were determined as germination indices. Root and shoot length, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight and seedling dry weight were evaluated as growth factors at the end of the incubation period. Second experiment was carried out to study the effect of temperature on seed germination. It was observed that both the physical and chemical scarification methods were effective in enhancing S. leptoclada seed germination and growth. The highest germination rate, percentage of germination and germination vigor index was observed with Moist Chilling (Soaking in water at 2?C for 14 day), 0.2% potassium nitrate (soaking for 48h) and GA (at concentration of 250 ppm soaking for 48h) in compare with control. Also the highest growth factors were found in Moist Chilling (Soaking in water at 2?C for 7day) treated seeds and the lowest occurred in hot water treatments. The other results showed that higher temperature was more effective lower temperature for seed germination.