Comparative study of the effects of different soluble salts on seed germination of wild marigold (Tagetes minuta L.)

Abstract

Wild marigold (Tagetes minuta L.) is an important aromatic plant species with a high industrial value in its essential oil. It has spread worldwide due to its wide adaptations. However, meager information is available regarding its salt tolerance. Understanding its seed germination behavior is crucial for establishing the plant species in new saline habitats. The present work focuses on the effect of five soluble salts (CaCl2, KCl, MgCl2, Na2SO4 and NaCl) on germination velocity, salinity tolerance index and germination percentage of wild marigold. Five concentrations (0, 50, 100, 150 and 200 mM) of the salts were given in a two-factor factorial, completely randomized design (CRD). The experiment was performed in a programmed culture room at 25 ± 2 ℃ under 16 h of light (PAR: 40 µmol m−2 s−1) and 8 h dark. Findings suggest that seeds of wild marigold exhibit the highest germination percentage (GP) of more than 95% in non-saline (control) conditions. The trend of germination inhibition due to different soluble salts was in the order: Na2SO4 > KCl > NaCl > CaCl2 > MgCl2. There was a significant decrease in germination velocity (0–40.56) and salinity tolerance index (0–96.67) with the elevated levels of salinity (all applied soluble salts). The dose resulting in a 50% decrease in seed germination, i.e., IC50 (inhibition concentration value) of 79.9 mM of solute salts, was obtained for wild marigold. There are strong indications that wild marigold can tolerate moderate salinity levels and can be appraised as a salt-tolerant aromatic crop. The present study's findings will open future horizons of salt tolerance in wild marigold by identifying potential salt tolerant breeding lines.