Gas composition and oxygen supply in the root environment of substrates in closed hydroponic systems.
Projekt
Überblick
Beschreibung
The objective of this study was to get more information about the root zone, mainly the gas composition in substrates, which are used in closed hydroponic systems. For analyses of carbon dioxide (CO 2 ), ethylene (C 2 H 4 ) and oxygen (O 2 ) different methods were proofed and used. For analyses of carbon dioxide and ethylene, a gas sampling system was used to get gas samples from the root zone. CO 2 gas samples of 20 ml were analyzed with an IR sensor by air diffusion into a measuring cuvette. C 2 H 4 gas samples of 3 ml were analyzed using gas chromatography (GC). Gas sample cells were inserted into the substrates at 2 or 3 heights. Dissolved oxygen was determined with a membrane covered galvanic sensor, in the air, in the in the nutrient solution, and in the drain solution. To analyze the root zone, a hydroponic system with chrysanthemum cv. 'Snow' on 3 substrates was performed. The following substrates were used: Sawagrow (polyester fiber), polyester fleece (thin layer of fleece), and UC-mix (peat substrate). Gas sampling at 2 or 3 heights from root zone did function well, results ranged from 350 ppm t
