Direct Seeding Compromised The Vitamin C Content of Baby Vegetables and the Glucosinolate Content of Mature Vegetables in Asian Leafy Brassicas

Abstract

To reduce labor requirements and costs, farms are increasingly opting to eliminate the transplanting step through direct seeding. However, this may compromise the nutritional quality of crops, as many nutrients are involved in the plant’s defense mechanism against stressors associated with transplantation. Hence, this study investigated the effect of direct seeding on the nutrient content of bok choy (Brassica rapa subsp. chinensis), choy sum (Brassica rapa subsp. chinensis var. parachinensis) and mao bai (Brassica oleracea var. capitata) at the baby and commercially mature stages. Direct seeding had distinct effects on each stage. Directly seeded baby vegetables had 39 to 51% less ascorbic acid and 21 to 30% less vitamin K than transplanted baby vegetables (p < 0.05). For mature crops, direct seeding decreased the total glucosinolate content by 12 to 40% (p < 0.05). Thus, while direct seeding may profit vegetable producers, its impact on nutrient quality merits careful consideration.

Keywords: transplanting, preharvest stress, antioxidants, Ascorbic acid, Carotenoids, phylloquinone