Effects of Ultrasound Stimuli on Acceleration of Brown Rice Germination

The effects of ultrasound stimuli on the germination and sprout growth of brown rice were investigated. Ultrasound was applied to brown rice at the frequencies of 28, 40, and 60 kHz before germination test and it was germinated in three methods (Type I, II and III). Type I was to soak brown rice into water for 60 hours. Type II was to expose brown rice to air for 48 hours after soaking them into water for 12 hours. Type III was a repetitive method of water-soaking and air exposure for 12 hours respectively. The most effective method for the germination was Type III without ultrasound. However, Type I was a best method after ultrasound treatment. As power of ultrasound increased, sprouts grew faster after brown rice were treated in 40%, 70%, and 100% power (0.137, 0.241, and 0.344 $W/cm^2$) at 40 kHz. The good treatments for fast sprout growth of brown rice at each frequency were the 28 kHz-10min group, the 40 kHz-5min group, and the 60 kHz-20min group of Type I. The best effective treatment was the 40 kHz-5min group at 0.344 $W/cm^2$ and at that condition the time required for sprout growth of 2.5 m was 51.9 hours. The ultrasound stimuli was very effective in the beginning of the rice germination, and the germination ratio was more than 95% in all ultrasound treatments.

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