Corn seedlings use their roots to communicate about possible competition in shared soil
While plants can’t necessarily choose where every seed will sprout, they’re not completely passive about how the interact with their environment. Aside from reacting to possible predators, plants also need ways to deal with competition from other plants. In some species, this can mean pushing resources from growing roots to growing stems and leaves faster in order to stay out of a neighbor’s shadow. Of course, reacting to competition that’s already creating a problem may not be enough, which is likely the reason some plants seem to communicate their stress to their nearby relatives.
To investigate how these kinds of warning might work, scientists planted corn, then tricked it into worrying about competition. Every day, corn seedlings growing on their own had their leaves brushed to simulate contact with a neighbor’s leaves in the breeze. This was known to spur the seedlings to grow taller faster, which was observed as predicted. Once a seedling reacted to its faked competition in this way, the plant was uprooted so a new seedling could take its place in the same soil. Even though that second plant had never been brushed, it started growing taller as if it had experienced signs of competition. Since the two seedlings had never had direct contact with each other, and control plants that were simply transplanted didn’t react this way, researchers suspect that the seedlings are communicating through the soil.
Signals in the soil
While the exact chemical mechanisms remains to be isolated, the assumption is that this system would allow a plant to warn its kin of crowded conditions. Other seedlings nearby would then start growing taller faster, presumably beating out competition from other kinds of plants nearby. It might not be a huge benefit to the initial messenger that sounded the alarm, but it would help that species outpace the competition in the long run.
If humans can isolate this mechanism, we will be able to better understand plants’ health and possibly even coach them into more advantage growth patterns. From a passive standpoint, detecting this kind of chemical communication in soil may help us diagnose stressed ecosystems. More actively, it may help farmers better understand and control the growth rates of their crops, either encouraging more competitive growth rates, or maybe slowing things down to establish stronger root structures.
Source: Plants 'talk to' each other through their roots by Hannah Devlin, The Guardian