Do plants listen to music? How can a plant possibly respond to music? Well, plants breathe through their many mouths, which are also known as stomata. And it has been discovered that plant stomata respond to music! Music and Plants? A few years ago, scientists at the University of California, San Diego in the United States discovered a signal mechanism that controls a plant's stomata. The two cells that form the stoma consist of specialized cells (guard cells) that are tuned to the resonant frequency of calcium. When exposed to this frequency the stomata close. However, if the frequency is not exactly right the cells will open again within an hour. This happens even if the concentration of calcium is so high that the stomata would normally close. Experiments showed that exposure to high tones was more or less directly responsible for increased gas exchange, and not just after an hour. Music increases growth When specific music, high tones or bird song cause the plant to vibrate, but not at the exact frequency for calcium resonance, the stomata will open after a lapse of time, even though the plant would keep them closed under normal circumstances. Tests have shown that a precise leaf fertilizer, tuned to the plant will have more effect on the development and growth of the plant if its stomata are wide open. Which is logical, because plants absorb leaf fertilizer via their stomata. Combinations of frequency and leaf fertilizer are available for many different crops. But there are still some catches to this method. If the stomata are forced to remain open the plant will not be able to control the amount of water lost via transpiration and so it risks dehydration. So exposing your plant to music for more than 3 hours a day could endanger its health. Don’t overdose on music There could also be negative effect on your favourite plants if the volume or frequency are too high. But this cannot yet be explained based on the opening and closing of the stomata. The negative influence of a too high a frequency could possibly be explained using a technique known shell resonance. Shell resonance Besides resonance, which causes stomata to open under the influence of music or specific tones, there is another technique that might be able to explain the effects of music on our plants. This technique is known as shell resonance and it stimulates or inhibits the synthesis of proteins in plants. Various tones have a role to play here. The theory behind this that proteins, which consist of amino acids, are synthesized in tune to the vibration. Each amino acid should have its own frequency and therefore, each protein its own range of frequencies. So theoretically, the correct sequence of tones should stimulate the creation of proteins by resonance. The influence of resonance in the human body is also the subject of research. Transcutaneous ElectroNeural Stimulation or TENS is a technique that utilises a specific frequency to stimulate the generation of specific substances in the body. For example, a frequency of 10 Hz is thought to stimulate the creation of the neurotransmitter serotonin (the same frequency as α-waves). And guess what? Serotonin is an amino acid. The reason that different tones could be such an influence on plants is because of hormones, such as auxin which is one of the substances responsible for cell extension and fruit formation, only consist of two amino acids. Allowing the plant to vibrate just long enough at the frequencies of these two amino acids should increase the production of the desirable plant hormones thus resulting in bigger shoots. Music could also have an influence on seed germination. A publication in the ‘journal of alternative and complementary medicine’ describes a experiment in which music resulted in a higher germination percentage (P < 0.002) and in faster germination (P < 0.000002). By the way, it appears that sound did not have any significant effect on germination. So it seems here that multiple frequencies are significant and because germination is all about hormones, it is very probable that shell resonance has a role to play here. Plants Prefer Classical Music... A possible explanation for plants reacting positively to classical music and not to heavy metal, is that purer tones are used in classical music, while heavy metal is full of guitar effects such as distortion and overdrive which we certainly cannot consider as pure tones! Green Ears Even though techniques to encourage plant growth have been around since the time immemorial, the art itself is dying and present-day growers only have a fraction of the knowledge of their forefathers. Yet, at the moment it is not exactly clear how music influences the development and growth of plants, but more and more is being discovered about resonance physics and we are closer than ever to solid scientific proof and theories in this area. Maybe, in twenty year's time people will laugh if you say that plants don't have ears!