Root Growth and Plant Performance

Just been reading thought a Hydroponic Book, Hydroponics A Practical Guide for the Soilless Grower 2005. Found this to be interesting information.

Anyone have any thought on this citation.


A large and extensive root system may not be the best for most hydroponic
growing systems. Rather than the greatest size (mass), active efficiently functioning
roots are what is needed, since the nutrient solution continuously
bathes most of the root system, thereby requiring less surface for absorption
to take place. One of the major problems with the NFT tomato hydroponic
system (see page 127–141), for example, is the large root mass that develops
in the rooting channel, which eventually restricts O2 (Antkowiak, 1993) and
nutrient solution penetration; the end result is a problem called “root death.”
Similar extensive root growth occurs with other types of growing systems,
particularly with ebb-and-flow systems, where roots frequently grow into the
piping that delivers and drains the growing bed of nutrient solution.
Similar extensive root growth is obtained with most hydroponic/soilless
systems; roots frequently fill bags and blocks of media and sometimes grow
through the openings in the outer walls of bags and media containers. The
question is “does a large root mass translate into high plant performance?”
The answer is probably no, if there is more root surface for absorption than
needed. In addition, roots require a continuous supply of carbohydrates, which
can be better used to expand top growth and contribute to fruit yield.
Unfortunately, the question as to root size has yet to be adequately
addressed. It should also be remembered that roots require a continuous
supply of O2 to remain healthy and functioning. Roots will not grow in
anaerobic conditions. Hydroponically speaking, a large, ever-expanding root
system probably does not necessarily translate into greater top growth and
yield and, in fact, may actually have some detrimental effect.

I feel those are very good points, and probably true with the majority of hydro/aero setups. I have always though that most soilless setups have not left ample room for roots to breath. In my first setup, I used 10" diameter pvc and made em 2' tall. It only took me a month to realize that I had underestimated, even with that large of a rootzone. My current setup uses a 40 gallon capacity bin for the rootzone of a single plant. Sounds crazy, I know.

Anyone else care to take a read and give some thought?

I'm one of those folks that believes roots can be the window to the plants soul. In a DWC set I found 14gal in a 18gal tote to be just enough for two, giving my original plan was four plants per tote. It CAN be done with less, as many have proven, yet from my limited experience 4-6gal is a nice happy place for roots. Ph tends to be a bit more stable, as well as temp in the higher volumes.

Far as root having usable healthy roots your in good shape if the roots appear to be able flow freely in the solution. Root pruning may be a viable option for those having problems.