CHANGES IN QUERCETIN CONCENTRATION IN ONION (ALLIUM-CEPA L) OWING TO LOCATION, GROWTH STAGE AND SOIL TYPE

A study with onion investigated the variation in the concentration of the potentially anticarcinogenic flavonol, quercetin owing to location , soil type and growth stage. Seven genotypes grown at two locations w ere analysed for aglycone and total quercetin concentration by reverse -phase high-performance-liquid-chromatography (RP-HPLC). Out of seven genotypes investigated, four showed significant differences (P = 0.05) in total quercetin concentration between two locations. In 1993, 'Tex as Grano 1015Y' (TG1015Y) bulbs collected at five growth stages were a nalysed for quercetin concentration by RP-HPLC. Quercetin concentratio n in 'TG1015Y' at different growth stages showed slight differences. F urthermore, quercetin concentration in bulbs harvested at second growt h stage (23 March) was significantly (P = 0.05) greater than at the fi rst growth stage (9 March). A slight difference in total quercetin con centration due to soil was noticed. This study shows that the site of growth of onion is a major environmental factor in determining quercet in concentration but soil type and growth stage are not important.