Seasonal climate effects on root colour and compounds of red radish

Abstract

Abstract ‘Nevadar’ radishes were grown throughout the year. Climate parameters (mean temperature, mean irradiation) and quality characteristics of radishes fulfilling consumer quality requirements, such as root colour, glucosinolates, monosaccharides and pectic substances, were determined. The quality characteristics strongly differed depending on the seasonal climate conditions. The seasonal dependence ranged from a slight climate influence (alkenyl glucosinolates r 2 = 0.23), over a moderate climate effect (indolyl glucosinolates r 2 = 0.40, glucose r 2 = 0.50) up to a strongly distinctive climate influence (hue angle r 2 = 0.77, chroma r 2 = 0.72, fructose r 2 = 0.81, pectic substances r 2 = 0.99). Therefore, according to consumer‐oriented quality production of radish, the temperature and irradiation influence should be taken into account in the production process. Recommendations for quality production of radish will be the selection of bright red cultivars marked by a high photosynthetic capacity (yield > 0.80 mV) at relatively low mean irradiation intensities (50–100 µmol m 2 s −1 ) and lower mean temperatures (11–13 °C). Thus sufficient photochemical energy can be provided for the synthesis of quality‐determining compounds. For the production of bioactive radishes showing particularly relatively high contents of indolyl glucosinolates, cultivation should be carried out in spring and autumn. In summer cultivation, consumer preferences in taste can particularly be satisfied with the desired contents of alkenyl glucosinolates and monosaccharides. © 2002 Society of Chemical Industry