Salt in Irrigation Water Affects the Nutritional and Visual Properties of Romaine Lettuce (Lactuca sativa L.)

• Published in: Journal of agricultural and food chemistry 2008-05, Vol.56 (10), p.3772-3776
• Main Authors: Kim, Hyun-Jin, Fonseca, Jorge M, Choi, Ju-Hee, Kubota, Chieri, Kwon, Dae Young
• Format: Article
• Language: English
• Subjects: Agriculture - methods; appearance (quality); beta-carotene; Biological and medical sciences; carotenoids; Carotenoids - analysis; color; crop quality; Food Chemistry/Biochemistry; Food industries; food quality; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; irrigation water; Lactuca - chemistry; Lactuca - drug effects; Lactuca - growth & development; Lactuca sativa var. longifolia; lutein; nutritive value; phenolic compound; phenolic compounds; Phenols - analysis; plant growth; romaine lettuce; saline water; Salinity; Salinity stress; salt; salt stress; secondary metabolites; sodium chloride; Sodium Chloride - administration & dosage; Sodium Chloride - analysis; temporal variation; Water - analysis; β-carotene
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0733719

The influence of salinity stress on the growth, appearance, and nutritional compounds, especially phenolic compounds and carotenoids, of romaine lettuce (Lactuca sativa L.), a low salt tolerant plant, was studied. The dry weight, height, and color of the lettuce plants were significantly changed by long-term irrigation (15 days) with higher NaCl concentration (i.e., >100 mM). However, no significant differences were observed in the growth and appearance among the control, all short-term treatments (2 days; 50, 100, 500, and 1000 mM), and long-term irrigation with low salt concentration. Moreover, in romaine lettuce treated with long-term irrigation with 5 mM NaCl, the total carotenoid content increased without color change, and the contents of major carotenoids in romaine lettuce, lutein and β-carotene, increased 37 and 80%, respectively. No differences were observed in lutein and β-carotene contents in short-term-treated lettuce. The phenolic content of the romaine lettuce declined with short-term salt irrigation, whereas there were no significant differences among treatments exposed to long-term irrigation. This research indicates that long-term irrigation with relatively low salt concentration, rather than short-term irrigation with high salt concentration, can increase carotenoid content in romaine lettuce without causing a tradeoff in yield or visual quality.