Radicle emergence test for soybean vigour testing

This study was carried out to determine the use of single counts of radicle emergence to test seed vigour and estimate seedling field emergence of soybean ( Glycine max ) seed lots. Results of radicle emergence (RE) (production of 2 mm radicle) at 20°C for 48 hours and 25°C for 24 hours, mean germination time (MGT), tetrazo­lium vigour test (TZ) and field emergence (FE) were compared using nine soybean seed lots with standard germination above 80%. The single counts of RE performed at 20 and 25°C were significantly correlated with the MGT at the same temperature ( R 2 = 0.82 and 0.89, respectively) and with the TZ vigour ( R 2 = 0.96 and 0.93, respectively). The RE counts at both temperatures also estimated the field emergence of the seed lots ( R 2 = 0.74 at 20°C and 0.68 at 25°C). The TZ vigour results had a significant correlation with the seedling field emergence ( R 2 = 0.70). Results indicate that a single count of radicle emergence after 48 hours at 20°C or 24 hours at 25°C is an efficient option for soybean seed vigour assessment.