Betacyanin and growth of beetroot (Beta vulgaris L.) in response to nitrogen fertilization in a tropical condition

Abstract

A series of studies was carried out to explore the possibility of beetroot cultivation at highlands in the tropics. This was initiated by a study on the effect of temperature and duration of beetroot storage on betacyanin content after determination of a wavelength that giving the maximum absorbance of betacyanin extracts from beetroots. The second study was designed to examine the response of betacyanin and plant growth to nitrogen (N) fertilization. A randomized block design was used to impose the treatment of N fertilizer (Urea) consisting of 0, 0.15, 0.30, 0.45, and 0.60 g N/plant with five replicates. The maximum absorbance of betacyanin extracts from fresh beetroots was attained at the wavelength of 536 nm. Betacyanin content of beetroots increased from 229 ml/l to 639 ml/l during 7 days storage under room temperature (± 22 0 C), and was declined after slight increases when stored at lower temperatures. Nitrogen fertilization with the dosage of 0.6 g N/plant reduced betacyanin content up to 25 % from 351.5 to 257.6 ml/l, while root yield and total dry weight (TDW) increased with the supply of N fertilizer.