GETTING TO THE ROOT OF IT ALL
While we may feel secure in the fact that our plants
are being provided plentiful supplies of root-essential
oxygen, moisture and nutrient ions, there are other
root physiology factors in soilless systems that need
some consideration. Root function is dependent on
a wide range of interrelated factors. Just as in soil,
hydroponic roots can be affected by temperature,
microbial populations, competition, pathogens, salinity, toxicities and root exudates.
Root Growth
Root growth is an ongoing process. Over time, root
density increases as new roots are produced. The
regeneration of new roots is essential for normal
plant development, as the majority of nutrients are
absorbed through younger root tissues.
Roots respond to gravity, and to touch when they
contact a solid surface. For example, in a restricted
growing container, roots tend to head downwards
and form a mat in the lower regions of the growing
substrate. Eventually, as roots continue to grow, the
point will be reached where extreme root binding
occurs—even in plants receiving a regular supply
of nutrients—and overall plant growth is restricted.
The size of the container must allow for this
continual root growth.
Healthy-looking roots.
“THE REGENERATION of new
roots is essential for normal
plant development, as the
majority of nutrients are
absorbed through younger
root tissues.”
Root Oxygenation
Oxygen is a vital component of root physiology. The
superior oxygenation of the root zone and nutrient
solution that hydroponics provides helps improve root
health, as without enough oxygen to complete the respiration process, roots will suffocate. Plants will exhibit
a strategy called oxytropism, where roots will avoid
growing in oxygen-deprived areas such as water-logged
soils, overwatered hydroponic substrates and stagnant
nutrient solutions.
Some plants require large amounts of oxygen within
the root zone, particularly when growing in the
protected, warm conditions provided year-round with
indoor gardens. A restricted root zone is limited in
how much oxygen it can hold, so it relies heavily on
oxygen replenishment. This can be carried out by dissolved oxygen in the nutrient solution, or by oxygen
percolation down into the root zone during irrigation.
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Maximum Yield USA | November 2015
Many hydroponically grown plants develop dense root systems.