Effect of hydroponic and organic fertilizer on growth, safety, and storage quality of watercress (Nasturtium officinale)

Abstract

© 2020 International Society for Horticultural Science. All rights reserved. Watercress is a healthy vegetable which contains natural antioxidants. However, plant production methods affect difference in quality of product. This study investigated the effect of production methods on growth, safety, and antioxidant capacity of watercress during production and low temperature storage. Fifteen-day-old seedlings were transplanted to soil culture (no fertilizer), soil with organic fertilizer (cow manure), and non-circulating hydroponic (Hoagland solution). Results showed that hydroponic treatment presented significantly higher growth than organic treatment. Growth of organic plants at 40 days after transplant was approximately the size of 30-day-old hydroponic plants. Cow manure in organic treatment caused contamination of E. coli and coliform. After harvest, organic treatment (40 days old) and hydroponic treatment (30 days old) were stored in OPS plastic box at 8 and 25°C for 0, 3, 6, 9, and 12 days. The low temperature (8°C) could extend shelf-life and reduce leaf yellowing. Hydroponic treatment could be stored for 9 days at 8°C, while organic treatment could be stored for 6 days. During storage period, hydroponic treatment revealed statistically higher nitrate content (3,018-3,704 mg kg-1 FW) than organic treatment (436-759 mg kg-1 FW). However, nitrate content of hydroponic treatment was reduced by water soaking (1 day) before harvesting (2,434 mg kg-1 FW). The total antioxidant capacity was similar in watercress of both treatments. Among these results, hydroponic watercress represented an interesting alternative due to its rapid growth, no E. coli and coliform contamination, long shelf-life, and water soaking could reduce nitrate content before harvesting.