Effects of different levels of salinity stress on germination properties of medicinal plant Salvia Leriifolia Benth.

In order to study the effects of different levels of salinity stress on Salvia leriifoliagermination indices, an experiment was conducted at physiology laboratory, Faculty of Agriculture, Ferdowsi University of Mashhad in 2014. The experiment was arranged based on a completely randomized design with three replications. Treatments were different levels of salinity including 0, 25, 50, 75, 100, 125, 150, 175 and 200 mmol, prepared by mixing NaCl and CaCl2 in a 10:1 molar ratio. Evaluated indices were germination percentage and rate, seedling length, germination seedling reduction rate, seedling dry weight and vigor index. Four non-linear regression models (linear, polynomial, 2-piece segmented and Logestic) were compared to describe the germination characteristics in different levels of salinity. The 2-piece segmented model was selected as the best one to predict germination percentage and rate, seedling length, reduction in the rate of germination and vigor index with RMSE 3.22, 0.2, 0.25 and 0.4 and R2 0.99, 0.98, 0.99 and 0.99, and Logistic model was selected as the best model with RMSE 0.01 and R2 0.98 to predict seedling dry weight, respectively. The results showed that by increasing of salinity levels, germination percentage, germination speed, seedling length, dry weight of seedling and vigor index significantly decreased. But there were no significant differences in germination indices up to 90 mmol salinity. Germination of Salvia leriifolia seeds could tolerate up to 90 mmol salinity without any significant decrease in germination properties.