Impact of Audio Sound Waves on Efficiency of Saffron (Crocus sativus L.) Corms under Controlled Conditions

The effect of sound waves on saffron corms in the controlled environment and aeroponic cultivation on the amount of flowering and production of saffron stigma are investigated in this study. Sound waves with a sound pressure level of 77 decibel for 15 minutes a day were induced into two groups of corms. In the first group, the effects of sound waves with frequencies of 0.5, 1 and 2 kHz and also a type of classical music sound on saffron corms in different periods of flowering induction, flowering and the whole period (flowering formation) were studied. In the second group, this test was performed on bulbs only in the flowering period with single frequencies of 4, 8, 12 and 16 kHz. Also, the effect of sound application time in 15, 30 and 60 minutes per day at 16 kHz frequency on the corms was investigated. Statistical results showed that in the first group, induction of single frequency sound led to production of flowers and also saffron stigma amounts less than or equal to that of the control group. However, these differences were not significant except for the treatment on flowering period at 500 Hz (p < 0.05). The application of musical sound in different stages of corm growth reduced its flowering efficiency compared to the control group. Among the treatments of the second group, the mean values of number of flowers at 4 and 8 kHz frequencies were higher than that of the control group. In the treatment with a frequency of 4 kHz, which produced the highest amount of flowers and stigmas, the flowering efficiency of saffron corms increased more than 4.0%. Also, increasing the duration of sound application from 15 min to 30 and 60 min per day caused a significant increase in the number of flowers and the flowering efficiencies had increased by 6.0 and 10.4% compared to that of the control group during 30 and 60 min, respectively.