COMPARISON THE GERMINATION CHARACTERISTICS OF TWO ECOLOGICALLY DISTINCT POPULATIONS OF JOHNSONGRASS (SORGHUM HALEPENSE L.)

Abstract

To study the effect of different dormancy breaking treatments on Johnsongrass seed germination, laboratory trials were conducted at the Research Centre of Flakkebjerg, University of Aarhus, Denmark in 2011. Seeds of Johnsongrass from Iran and Serbia were used in this study. Seeds were divided into two groups; deglumed and intact seeds. Seeds were then exposed to four seed treatments: 1) NaOCl (700 mM) (10 h), 2) H 2 SO 4 (36 N or 10 N) (30 min), 3) H 2 O 2 (900 mM) (30 min) or 4) boiling water (5 min). Intact seeds were also exposed to prechilling and scarification by. After treatments, seeds were incubated at 28 C or fluctuating temperature of 35/20 C (16 hours at 35 C in light and 8 hours at 20 C in dark) for 28 days. Seeds collected from both locations responded differently to the applied treatments. Submerging seeds collected from Iran in the H 2 O 2 and NaOCl resulted in the highest seed germination; whereas for the seeds collected from Serbia, submerging in the H 2 O 2 resulted in the highest germination. Averaged across soaking treatments, removing the glumes of Johnsongrass seeds led to an increase in seed germination by 17%. In general, seeds collected from Serbia were more dormant than those collected from Iran. Germination was increased with the alternating temperature as compared with germination at constant temperature. In conclusion, the glumes might be causing the seed dormancy in Johnsongrass seeds and this dormancy is affected by the geographical locations of the maternal plants.