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Ozone Generators May Damage Plant Root in Hydroponics Applications

According to an article published in the Proceedings of the National Academy of Sciences, ozone, a major smog constituent, inhibits the ability of plants to open the microscopic pores on their foliage and breath. HydroponicSearch.com was interested in learning more about the effects of ozone on the plants’ root-zone.

We purchased a simple bubbler (waterworks) system that held up to nine plants. We wanted a system that held multiple plants in order to accurately interpret the results. The system was made from a 10-gallon rubber-maid tub, using two air-stones and one fairly powerful, external pump to oxygenate the nutrient solution.

We had 4 mature plum tomato plants from which we clipped nine cuttings to use in our experiment. We took the clones from one of the healthiest of the four mature tomato plants. We knew the genetics were good and were excited to see the results.

The clones rooted nicely and were placed in 1" rockwool cubes and placed in small 3" net-pots with clay pellets for structural support. The clones were allowed to grow normally for a month without the addition of ozone.

We used organic fertilizer (3-3-3) with organic biological stimulants to make the nutrients available to the plants.

30 days after we transplanted the rooted clones in the hydroponics system, we monitored the roots and noticed everything appeared healthy and in good condition. Plant growth was vigorous and the foliage was green and healthy with no signs of stress or disease.

On day 31 we placed an ozone generator in the grow room. To ensure the ozone would penetrate the nutrient solution, we placed the external pump used to aerate the solution over the exhaust (mouth) of the ozone generator. This allowed the pump to feed ozone directly into the solution by diffusing it through the air-stones.

About 7 days later (Day 38) the leaves were getting crisp - similar to the effects of nitrogen burn. They were fairly stiff and turned a bronze-like color. On day 60 the roots had a slimy-brown appearance and stopped developing from the time we introduced the ozone 30 days prior.

It appears that the ozone were killing the roots of the plants. Additionally, plant growth and fruit development ceased completely. On day 30 the plants were approximately 1' (ft) in height. On day 60 they are about 1' 3". in height with only 3" (inches) in new growth.

15 days later (Day 75), most of the plants appeared dehydrated with wilted foliage and looked similar to crops that endure extreme heat stress. Some leaves remained normal however, and it was mainly the larger fan leaves. New growth was not observed.

The Air-line connected to the pump and the air-stone started to build a black-film that lined the inside of the air-line on the end connect to the pump.

We removed the ozone generator on day 75 to see if the plants would recover, however, by day 90 they were all beyond the point of recovery. There were no new root or foliage development and the plant continued to wilt until they were completely dried out.

We hypothesize that the ozone directly affected the roots of the plants. However, we are uncertain how the roots are affected or damaged by the ozone. It appears the ozone kill the existing root and prevent new shoots from developing. We also believe that ozone may have killed and/or drastically reduced the organic matter available in the nutrient solution. While this test was small and not quite scientific, it does suggest that ozone, added directly to the root-zone is not beneficial to the overall health of plants. We believe that ozone may damage the root of plants, kill organic matter in nutrient and/or cease plant growth and fruit development.

We hope to continue various tests using ozone to get a better understanding of how ozone affects plants' root, growth and fruit development.

This article courtesy of www.hydroponicsearch.com

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