Nitrogen nutrition and flavour compounds of carrots (Daucus carota L) cultivated in Mitscherlich pots

Carrots (Daucus carota L) of the cultivar 'Nanthya' F-1 were grown in Mitsc herlich pots containing quartz sand with inorganic nitrogen fertilisation ( five levels, four replications) and time-controlled drip irrigation. The ef fect of different nitrogen uptake on the yield and on the amount and compos ition of essential oils, sugars and organic acids was investigated. Sucrose , glucose and fructose were extracted and analysed by HPLC; L-malic acid an d citric acid were measured with an enzymatic test. Medium- and higher-boil ing flavour components were isolated as essential oils by simultaneous wate rsteam distillation and pentane extraction (SDE) and separated gas chromato graphically (HRGC-FID). Thirteen essential oil components were identified b y mass spectrometry as well as by comparison of retention times and quantif ied by external standards. The higher the supply of nitrogen, the higher wa s its uptake and as a consequence the higher were the nitrogen and nitrate contents of the leaves as well as the roots of the carrots. Carrots with lo wer nitrogen application had higher amounts of sucrose and essential oils b ut lower amounts of glucose and fructose. Fertilisation with nitrogen affec ted not only the total content but also the composition of the essential oi ls. A correlation between nitrogen nutrition and organic acids could not be found. (C) 2000 Society of Chemical Industry.