2019 ASHS Annual Conference

Different salts have been used for evaluating relative salt tolerance of crops. A greenhouse study was conducted to assess the effects of different salt compositions on the growth and visual quality of six herbaceous perennial ornamentals: ‘Angelina’ (Sedum rupestre), ‘Autumn Joy’ (S. telephium), ‘Blue Daze’ (Evolvulus glomeratus), ‘Blue Spruce’ (S. reflexum), ‘Indian Summer’ (Rudbeckia hirta), and ‘Sunny Border’ (Veronica longoflia). A total of four treatments were used, including a control nutrient solution prepared with reverse osmosis (RO) water and fertilizer (15-5-15) at a rate of 200 ppm N. The control nutrient solution was also used to prepare the three different saline solutions, which were: NaCl, NaCl + CaCl₂ (2:1 molar ratio), and NaCl + CaCl₂ + MgSO₄ (87%, 8%, and 5%, respectively). All three saline solutions were prepared at an equal electrical conductivity (EC) of 7.0 mS/cm. Rooted cuttings of the six species were received from a commercial company and transplanted to 2.6 L containers with potting mix. Following establishment, treatments were applied for a duration of eight weeks and weekly visual score and leachate data were collected, along with shoot and root tissue dry weight (DW) following termination of the study. Results showed a trend of reduction in all response variables in plants treated with saline solutions, regardless of the composition. For visual score, only one species, ‘Indian Summer’ (R. hirta), showed more sensitivity to NaCl than the other salt compositions. For the relative growth (DW of shoots, roots, total), no differences among salt compositions were observed, regardless of species. Interestingly, ‘Autumn Joy’ (S. telephium) and ‘Blue Spruce’ (S. reflexum) maintained excellent visual quality throughout the experiment, regardless of the salt composition, indicating that these two species were relatively salt tolerant. In conclusion, salt composition did not appear to affect the evaluation of relative salt tolerance of the six herbaceous perennial ornamentals tested in study.