PHYS.org: “The next time you find yourself lulled by the patter of rain outside your window, think how that same sprinkle might sound if you were a tiny seed planted directly below a free-falling droplet. Would you still be similarly soothed? In fact, MIT engineers have found the opposite to be the case: Some seeds may come alive to the sound of rain. In experiments with rice seeds, the team found that the sound of falling droplets effectively shook the seeds out of a dormant state, stimulating them to germinate at a faster rate compared with seeds that were not exposed to the same sound vibrations. The team’s findings, published in the journal Scientific Reports, are the first direct evidence that plant seeds and seedlings can sense sounds in nature. Their experiments involved submerging rice seeds in shallow water. Rice can germinate in both soil and shallow water. The researchers suspect that many similar seed types may also respond to the sound of rain. The team worked out a hypothesis to explain how the seeds might be doing this. They found that when a raindrop hits the surface of a puddle or the ground, it generates a sound wave that makes the surroundings vibrate, including any shallowly submerged seeds. These vibrations can be strong enough to dislodge a seed’s statoliths, which are tiny gravity-sensing organelles within certain cells of a seed. When these statoliths are jostled, their movement is a signal for seeds and seedlings to grow and sprout. “What this study is saying is that seeds can sense sound in ways that can help them survive,” says study author Nicholas Makris, a professor of mechanical engineering at MIT. “The energy of the rain sound is enough to accelerate a seed’s growth.” Makris and his co-author, Cadine Navarro, a former graduate student in MIT’s Department of Urban Studies and Planning, suspect that the sound of rain is similar to the vibrations generated by other natural phenomena such as wind. They plan to follow up this work to investigate other natural vibrations and sounds plants may perceive…”