Stimulating Effect of Low-Temperature Plasma (LTP) on the Germination Rate and Vigor of Alfalfa Seed (Medicago Sativa L.)

Low-temperature plasma (LTP) treatment was applied to stimulate the seed of alfalfa (Medicago sativa L.) for better germination rates and vigor with the use of an inert gas, namely neon, at various discharge power levels. The seed passed through a neon-plasma glowing zone between two horizontally parallel electrode plates within the glow discharge chamber of a seed processing machine with an internal 2~8 mm atmospheric pressure. The seed were treated for 20 s. The LTP-treated seeds were germinated at 20 ^oC in a germination chamber, and seedling emergence was evaluated at 24-h intervals for up to 10 days. LTP stimulation significantly increased the germination rate and vigor versus an untreated sample. Among ten discharge power levels, the 20 W treatment had the most significant effect on the rate and vigor. The use of 20 W treatment increased the germination rate and vigor by 11 % and 22 %, respectively, relative to the control. LTP treated seeds that were stored for 20 days also had higher germination vigor than those stored for 4 days. These results suggest that the use of the LTP technique with a seed processing machine is effective and practical for the purpose of stimulating crop seeds for improved germination.