Do you notice a difference in the nodal root system of the two corn plants shown above? The plant on the left was grown in a simulated moderate weed pressure environment where the weeds grew 4 inches from the plant.Notice how its nodal root system is shorter and how they are growing straight down almost as if it was trying to get away from any neighbouring weed competition.In reality corn plants do read their environment and they will respond to it.It has been discovered that it is the reflected light ( called phytochromes ) that comes off nearby competitive weeds that makes the corn plant react in this manner.The corn plant on the right was grown in a simulated weed free environment.As you can see its nodal root system is much more prolific and reaching out in all directions.It will be able to interface with more soil volume thereby having greater opportunity to extract more water and soil nutrients from a greater volume of soil.This experiment helps shed some light on why researchers
are adamant that you need to keep the crop weed free from the 3 true leaf stage until the 8 true leaf stage in order to maximize yield.