Has anybody see an extra grow of the root system of your plants when they are cultivated in a hi-tech? I've read that a cultivation in a high light environment generate a greater nutrient need which implies a growing of root system to absorb more nutrients according to its greater demands. Is it a natural plant response in order to improve the general fitness of the plant or may result in a non-balanced morphology?. Is it useful or simply implied in a better response to adverse conditions of a punctual nutrient decay or act as a anormal growing to paliate a less efficient system of nutrient capture?
Supplimentation is the key to root growth. A plant with easy access to sufficient nutrients will not need to grow as large a root structure as one in a poorly supplimented aquarium. Age and type of plant will also be a factor. For example, George Booth once had a sword plant that had a root structure that covered the entire bottom of a 90 gallon aquarium and there's no way that it wasn't supplimented poorly. It was just an old plant of a type that grows lots of roots.
That looks logical Phil, but do you think it will be possible that a plant which absorbs mainly by roots planted in fast-growing conditions (high CO2, high light, high nutrient supply) needs to develop a bigger system of roots to catch more and more nutrients to perform the photosynthetic effort according to these over-optimal conditions?
Plant roots will allocate more resources, eg make more roots when there are limiting conditions in the water column. A number of studies showed this to be true but many plants will still grow roots even if there is 100% of the nutrients coming in from the water column.
But in general, limited water column conditions will drive more root growth and increase root/shoot ratios.
The most dramatic increases in root growth I have seen have always been due to nitrogen deficiency. This is easily observed in floating plants of Ceratopteris. Under low nitrogen conditions, even small plants get disproportionately large root systems. I have also seen this in Crypts where there is an increased production of those fine roots that grow straight up out of the substrate. It is also easily seen in Hygrophila polysperma.
root system increasing 
Linear Mode
