Contents of carotenoids, ascorbic acid, minerals and total glucosinolates in leafy brassica pakchoi (Brassica rapa L. chinensis) as affected by season and variety

Abstract BACKGROUND: Pakchoi ( Brassica rapa L. chinensis ) is economically and nutritionally important in East and Southeast Asia. The objective of this study was to evaluate the effects of season and variety on its phytonutrient content (carotenoids, minerals, ascorbic acid and total glucosinolates). RESULTS: Thirty‐five varieties were evaluated in one dry season and one wet season field trial at AVRDC–The World Vegetable Center, Taiwan. Mean carotenoid content was about 36% greater in the dry season than in the wet season trial. In contrast, ascorbic acid and total glucosinolate contents were 48 and 72% higher respectively in the wet season than in the dry season trial. Dry matter, calcium and iron contents were also 69, 69 and 21% greater respectively in the wet season than in the dry season trial. Significant differences among entries were found for most phytonutrients; the ranges of variety means were fourfold for total carotenoids, fivefold for iron and total glucosinolates and twofold for calcium. CONCLUSION: Season strongly influences the phytonutrient content of pakchoi grown in the tropics. Significant differences among entries were found for all phytonutrients, and there is potential to increase levels of individual phytonutrients through plant breeding. However, breeding would need to target varieties for either the dry or the wet season. Copyright © 2009 Society of Chemical Industry