Effect on yield, total phenolic, total flavonoid and total isothiocyanate content of two broccoli cultivars (Brassica oleraceae var italica) following the application of a commercial brown seaweed extract (Ascophyllum nodosum)

Field experiments were conducted to evaluate the effect of an unfortified extract, of Ascophyllum nodosum on yield and nutritional quality of two broccoli cultivars (‘Ironman’ and ‘Red Admiral’). Total phenolic, total flavonoid, and total isothiocyanates content were higher in all seaweed treatments compared to the untreated control. In ‘Ironman’ there was a 2.2 fold increase in total phenolic, 1.5 fold in total flavonoid and 2.6 fold in total isothiocyanates content, in the higher application rate compared to the control. Similarly in ‘Red Admiral’, there was a 2.3 fold increase in total phenolic, 2.6 fold in total flavonoid and, 2.2 fold in total isothiocyanates content. There was a consistent effect on the increase of total phenolic, total flavonoid and total isothiocyanates content, while there was no yield increase recorded at the lower seaweed application rate. Results suggest that application of seaweed extracts can significantly increase the amount of phytochemicals and improve the nutritional quality of broccoli.