Effect of different surfactants on germination and root elongation of two horticultural crops: implications for seed coating

Surfactants are often used in seed coatings to homogenise seed size and to protect seeds from injuries. Being near developing seeds surfactants may affect germination. Therefore the potential toxicity of different common surfactants on onion (Allium cepa) and lettuce (Lactuca sativa) seeds was evaluated. Anionic (sodium dodecyl sulfate and Aerosol 22) and non-ionic surfactants (Triton X100, Brij35, Tween 80 and Glucopone 600) were tested at 0.65, 6.5 and 32.5 g L-1. Seed germination, defined as seeds with a root > 3 mm, root length, fresh and dry weight of emerged plantlets were measured. In general, the highest surfactant concentration totally inhibited seed germination. Sodium dodecyl sulfate was the most hazardous while Tween 80 for onion and Brij35 for both plant seeds were the least phytotoxic compounds. Both non-ionic surfactants and Aerosol 22 were the recommended compounds for onion and lettuce seed coating at low concentrations (< 0.65 g L-1).