Plants listen to music too

You may have heard of Spotify for Student, Individual, and Family, but can you imagine “Spotify for Plant”? That’s right. Plants listen to music (Figure 1). Although plants don’t perceive music the same way we do, they are certainly affected by varying levels of sonication. As discussed below, several studies have shown the effects of different frequencies of sound and even entire styles of music on plant growth.

Figure 1. A comic representation of “plants listening to music” (Mazlan, 2019). Nevertheless, one would imagine larger speakers adjacent to plants to have greater efficacy compared to headphones.

Exposing common beans (Phaseolus vulgaris) and impatiens (Impatiens sp., organisms belonging to a genus of flowering plants) to different frequencies optimally affected seedling growth when sound wave frequency coincided with the average leaf dimensions of each plant species (Table 1) (Collins and Foreman, 2001). Although the mechanism explaining the association between leaf dimensions and optimal treatment frequency is not yet fully understood, it is suggested that sound waves with wavelengths corresponding to leaf dimensions create air pressure patterns conducive to increased transpiration (water movement), enabling desired metabolic changes (Collins and Foreman, 2001).

Table 1. Frequencies calculated using leaf dimensions of beans and impatiens coincide with optimal treatment frequencies (Collins and Foreman, 2001). *As impatiens did not have square dimensions, average of frequencies corresponding to each unique dimension (length x width) was taken to determine the calculate frequency.

In addition, chrysanthemum (Chrysanthemum sp.) seedling cuttings stimulated by sonication of 1 kHz for 3–15 days daily for 60 min showed significant differences in the content of soluble protein after 6- and 9-daylong sound stimulation (Yi et al., 2003). Soluble sugar of roots increased about 30 % and the activity of total amylase increased as well. Here, sonication was shown to accelerate important metabolic processes. Strawberries (Fragaria x ananassa Duchesne) were stimulated in the frequency range of 100 Hz to 2 kHz, resulting in stronger growth, deeper green leaves, earlier bloom, more fruit, and even increased disease resistance (Qi et al., 2010). Altogether, sound waves at the optimal treatment frequencies (or range of frequencies) have been demonstrated to be associated with desired characteristics in plants. Future studies could explore factors like sound intensity, type of sound wave (e.g. sine, square, etc.), periodicity of treatment, as well as combinations, eventually allowing us to determine sound configurations for optimal growth conditions.

On another note, seed germination rates of okra (Abelmoschus esculentus) and zucchini (Cucurbita pepo) were increased by gentle music itself. After 48 h, about 30 % more seeds germinated in both species when exposed to the music treatment compared to control (Creath and Schwartz, 2004). The music consisted of natural sounds, such as sounds of birds, echoes, and other gentle sounds. As all species coevolve with their surroundings, it is plausible that plants have evolved alongside their environments such that they are best suited to grow in the presence of natural sounds. To further explore the effects observed, it would be interesting to compare natural sounds (identical to the sounds present in the plant’s environment of origin) with enhanced versions of the same natural sounds (e.g. more repetitions, greater intensity, etc.); varying modes of enhancement would also reveal which components of natural sounds best increase plant growth.

All in all, it seems that sonication ranging from a few Hz to a couple kHz may enhance desirable characteristics in plants. Soon, professionals in the agricultural industry may see themselves accessing entre libraries of sound waves and musical sounds customized to suit their crops – “Spotify for Plant” could become a reality! Sound energy may be one more method of increasing crop yield, helping better serve the world’s growing population—all because plants too listen to music.

References

Collins, M.E. and Foreman, J.E.K., 2001. The effect of sound on the growth of plants. Canadian Acoustics, [online] 29(2), pp.3–8. Available at: <https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1358> [Accessed 19 Oct. 2019].

Creath, K. and Schwartz, G.E., 2004. Measuring Effects of Music, Noise, and Healing Energy Using a Seed Germination Bioassay. The Journal of Alternative and Complementary Medicine, [online] 10(1), pp.113–122. Available at: <https://www.liebertpub.com/doi/abs/10.1089/107555304322849039> [Accessed 19 Oct. 2019].

Mazlan, 2019. Plant with headphones. Available at: <https://dengarden.com/gardening/the-effect-of-music-on-plant-growth> [Accessed 26 Oct. 2019].

Qi, L., Teng, G., Hou, T., Zhu, B. and Liu, X., 2010. Influence of Sound Wave Stimulation on the Growth of Strawberry in Sunlight Greenhouse. In: D. Li and C. Zhao, eds. Computer and Computing Technologies in Agriculture III. [online] Berlin, Heidelberg: Springer Berlin Heidelberg.pp.449–454. Available at: <http://link.springer.com/10.1007/978-3-642-12220-0_65> [Accessed 19 Oct. 2019].

Yi, J., Bochu, W., Xiujuan, W., Daohong, W., Chuanren, D., Toyama, Y. and Sakanishi, A., 2003. Effect of sound wave on the metabolism of chrysanthemum roots. Colloids and Surfaces B: Biointerfaces, [online] 29(2), pp.115–118. Available at: <http://www.sciencedirect.com/science/article/pii/S0927776502001558> [Accessed 19 Oct. 2019].