The effects of higher carbon dioxide concentration in the kohlrabi growing on nitrate contents in bulbs

Frydrych, J.; Polach, J.

The effects of higher carbon dioxide concentration in the kohlrabi growing on nitrate contents in bulbs

1991

Frydrych, J. | Polach, J. (Vyzkumny a Slechtitelsky Ustav Zelinarsky, Olomouc (CSFR))

Varietal differences of nitrate contents have been studied in the controlled hydroponic system with artificial lighting in a glasshouse and in the phytotron in the kohlrabi bulbs of growing units under the conditions of higher controlled atmosphere with normal concentrations of carbon dioxide (340 micro l/l) or at higher concentration (1,000 micro l/l). White earlier varieties exhibited lower nitrate contents than the later ripening blue varieties. The plants growing under the conditions of lower carbon dioxide concentrations had always a higher weight in comparison with the control due to the higher photosynthetic production. There were no differences found between variants with increased and normal carbon dioxide concentration in nitrate contents in the phase of plants with small undeveloped bulbs. The atmosphere enriched with carbon dioxide helped to decrease nitrate contents in bulbs in comparison with the control by 37 % in the phytotron and by 25 % in the glasshouse. The most significant decrease in nitrate contents, 57 %, however, was achieved by the elimination of nutrient solutions with nitrate contents and by their replacement by fresh water a week before harvest.

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