By Maud Hinchee, PhD, Chief Science Officer, Agricen Sciences
For a germinating seed to survive and thrive, its root system needs to create a strong foothold and provide access to available nutrients and water. How does it do this?
It turns out that a new root is constantly making choices about where and when to grow based on the environment it encounters. Guided by its “root brain,” it makes decisions that maximise its access to water and nutrients as quickly as possible.
The root brain is found in the transition zone of the root tip – the area between the region of cell division and cell elongation. Here, the root receives and integrates multiple sensory signals in response to environmental cues. In response to those cues, it adjusts the rate and direction of its growth to ensure it has the best access to water and nutrients. By “deciding” which cells divide or elongate, the root can change where and how fast it moves through the soil.
This root brain doesn't act alone. Much as chemicals in our nervous system carry signals to and from our brains, similar processes happen in the plant. The plant hormone auxin, for instance, interacts with plant cells in a similar way that neurotransmitters (chemical messengers) interact with our own nerve cells to carry messages. Auxin is crucial to the root’s perception of and response to environmental signals, helping to control things such as the timing and rate of cell elongation, as well as potential sites for lateral root production.
The plant can even call in allies to obtain more auxin and bolster its root growth potential. In a microscopic barter, roots exude carbohydrates that act as food offerings to soil microbes. The microbes, in turn, produce auxins for the plant as a supplement that supports the plant in its goal to produce larger, more branched root systems.
The root systems of young seedlings also have another strong ally – the farmer. Farmers help by applying fertilizers, growth stimulators, and other products that assist the plant in growing strong roots or accessing nutrients and water. Such products can include agricultural biostimulants with signalling molecules that assist the root brain in making critical decisions that affect when, where, and how a root system develops.
The capacity for roots to assess and respond to the environment is a major part of how a plant wins the survival campaign for water, nutrients, light, and space. Root growth and development decisions made now and in the future can make or break a plant’s success—and the farmer is a key partner in helping the plant survive and thrive.
Dig deeper into the soil by downloading our Soil Microbiology & Biochemistry Booklet.