Effects of salinity stress on growth and photosynthetic activity of common basil plants (Ocimum basilicum L.)

The study evaluated basil plants’ response (var. Sweet Green) to increased concentrations of sodium chloride (NaCl) and macro- and micronutrients in the medium. The following variants were used: ½ Hoagland nutrient solution containing NaCl (0, 80 and 160 mM) and 4/2 Hoagland solution with 0 mM NaCl. Biometric and physiological parameters were measured 20 days after saline application. The application of 160 mM NaCl in nutrient solution caused the suppression of basil plants’ growth. The height of plants was decreased by 22% and the length of the roots was less by 60%. Control plants had 68% greater leaf area than those grown in the medium with 160 mM NaCl. Compared to the control, basil grown in ½ Hoagland solution with 80 mM NaCl and 4/2 Hoagland solution with 0 mM NaCl had leaf area reduced by 43.4% and 48.2%, respectively. A single plant’s highest fresh weight was found in the control variant (17.78 g) and the lowest in the ½ Hoagland solution with 160 mM NaCl (5.14 g). A negative effect of 160 mM NaCl in solution on the leaf gas exchange of salt-treated plants was found. At the same time, no negative influence of salinity on the content of photosynthetic pigments was found. The addition of NaCl into Hoagland solution did not affect the maximum photochemical efficiency (Fv/Fm) but modified the actual activity of Photosystem II (PSII). Increasing the concentration of macro- and microelements in the nutrient solution (4/2 of Hoagland and 0 mM NaCl) had a significantly lower negative effect on the growth and photosynthetic activity of basil plants.