Research matters ... adding oxygen to crops

Growers often question whether the oxygen content of hydroponic solutions is limiting plant growth, especially in summer when the oxygen-holding capacity of water is less.

In the experiments reported here, oxygen was added to nutrient solutions in a central container and the solutions distributed to crops via a dripper system. Various experiments were conducted in Canada in which cucumber 'Corona' or 'Curtis' was grown in 0.5m-long pillow bags containing fresh or used yellow-cedar sawdust (12 litres).

Some bags had water reservoirs in their base. The oxygen concentrations used ranged from two milligrams per litre (depleted) through 6.5 (ambient) to 30 or 40 (enriched). The plants were trained in a traditional umbrella system and experiments were started in summer, autumn and winter.

Enrichment with oxygen consistently improved cucumber shelf life. It also significantly increased their weight (nine per cent) in one summer experiment but without increasing fruit number. Oxygen escaped from the nutrient solutions very rapidly and had fallen from 30 to 10 milligrams per litre by the time the solutions reached the drippers. It is concluded that oxygen enrichment is difficult to sustain and its effects on yield are not consistent.

Effects of Oxygen-Enriched Nutrient Solution on Greenhouse Cucumber and Pepper Production by Ehret, Edwards, Helmer, Lin, Jones, Dorais and Papadopoulos (2010). Scientia Horticulturae 125 (4): 602-607. The contents of issues of Scientia Horticulturae and abstracts of papers are provided at www.elsevier.com/locate/scihorti


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