The effects of different gibberellic acid concentrations and application periods on germination parameters of stevia plant (Stevia rebaudiana Bert.)

In this study, the effect of different gibberellic acid concentrations on germination parameters of Stevia rebaudiana Bertoni (Sugar Grass) was investigated. The experiment was carried out with four replications according to the randomized plot design in the germination booths in the Department of Field Crops, Faculty of Agriculture, Van YüzüncüYıl University, in 2019. Four different concentrations of gibberellic acid (50, 100, 150, 200 pmm) were applied to the Stevia plant for 6, 12 and 18 hours and the measurements of the traits examined on the 7th and 14th days were evaluated using the Costat v 6.3 variance analysis and LSD Multiple Comparison Test. In our study, it was found that the application of gibberellic acid at 200 pmm concentration negatively affected all germination parameters and seed vigor index of Stevia seeds, and there was no significant difference in 50-150 pmm concentrations compared to the control group. Mean germination time and daily germination speed was found to be better with 6 hours of gibberelicasid application compared to 12 and 18 hours.When germination percentage, germination energy, mean daily germination, germination value and seed vigor index examined, there was no significant difference was found between 6, 12 and 18 hours of gibberellic acid applications. When compared with control group, gibberellic acid concentrations and application times did not give positive results on the germination parameters of the Stevia plant that we used. Different results can be obtained with studies that investigate the effect of gibberellic acid on the Stevia plant, where lower concentrations (0-50 pmm) and longer application times (24-48 hours) are examined. Further studies are needed in this context.