If you have ever felt a strange sense of calm listening to rain, you are not alone. Turns out, seeds buried in the soil feel something too, and it does not calm them down. It wakes them up.
Scientists at the Massachusetts Institute of Technology (MIT) have found, for the first time, that plant seeds can sense the sound of rain and respond by sprouting faster.
The study, published in the journal Scientific Reports, is the first direct proof that seeds can perceive natural sounds in their environment.
HOW DID SCIENTISTS FIND THIS OUT?
The researchers worked with rice seeds, which can germinate, both in soil and in shallow water.
They submerged roughly 8,000 seeds in shallow tubs and exposed some of them to dripping water, mimicking light, moderate, and heavy rainfall.
The rest were kept in identical conditions but without the sound of water droplets.
The results were striking. Seeds exposed to rain sounds germinated 30 to 40 per cent faster than those that heard nothing.
WHAT IS HAPPENING INSIDE THE SEED?
The key lies in tiny structures inside plant cells called statoliths. Think of them like little balls of sand sitting at the bottom of a jar of water.
These microscopic particles, denser than the surrounding cell fluid, help plants sense gravity and decide which way to grow.
When a raindrop hits a puddle or the ground, it creates powerful sound waves underwater. The sound is so powerful that the pressure is comparable to standing within a few metres of a jet engine.
These waves shake the seeds, which in turn jostle the statoliths out of their resting positions.
That jostling acts as a biological signal, telling the seed to start growing.
Seeds closer to the surface responded more strongly, which makes evolutionary sense.
If a seed is shallow enough to hear the rain, it is probably at just the right depth to absorb moisture and push through to the surface safely.
Lead researcher Nicholas Makris, a professor of mechanical engineering at MIT, put it plainly: the energy of rain sound is enough to accelerate a seed’s growth.
The team suspects many other seed types may respond similarly, and plan to investigate whether wind and other natural vibrations have the same effect.
