YIELD COMPONENTS AND GLUCOSINOLATE CONTENTS OF BROCCOLI CULTIVARS IN SUMMER-AUTUMN GROWING CYCLE

Abstract

In recent decades, interest for functional food has been increased. Plant derived food is important source of various bioactive compounds. The biologically active components in Brassica vegetables are the breakdown products of glucosinolates which have anticarcinogenic properties. Broccoli is included as a highly nutritious vegetable due to its mineral and vitamin content, fibres and bioactive compounds which depend on genetic, abiotic and agronomic factors. As numerous broccoli hybrid cultivars are available in Croatia, research with aim to select promising hybrid broccoli cultivars with appropriate agronomic and chemical traits was carried out during summer-autumn growing period of 2007. The field trial involving 13 hybrid broccoli cultivars was laid out according to four- replication block design. During harvest period basic morphometric values of top inflorescence were determined. Cultivar 'Montop' had the highest mass, diameter and yield of top inflorescence (506 g, 15.5 cm and 1.5 kg m-2). 'Green Magic' and 'Lucky' belong to the same range with slightly lower values of the mentioned parameters (457 g, 15.4 cm, 1.5 kg m-2 and 447 g, 14.1 cm, 1.5 kg m- 2, respectively). In all analyzed cultivars prevailing glucosinolate were glucoraphanin and glucobrassicin. There are significant differences in glucosinolate concentrations among cultivars. 'Fiesta' had the highest glucoraphanin level, 3.52 μmol g-1 dry weight (dw). This was followed by 'Agassi' and 'Marathon', which also achieved high glucoraphanin concentrations (2.85 and 2.80 μmol g-1 dw). 'General' obtained the highest glucobrassicin concentration (9.5 μmol g-1 dw), significantly higher than the other cultivars. 'Marathon' reached the highest total glucosinolate concentration (15.45 μmol g-1 dw). Neither cultivar can stand out with the highest values of agronomic parameters and bioactive components at the same time. The results point out 'Marathon' as the cultivar with a considerable content of glucoraphanin, glucobrassicin and total glucosinolates (2.58, 7.32 and 15.45 μmol g-1 dw, respectively), and with satiable marketable top inflorescence yield (1.06 kg m-2).