title: Salt in irrigation water affects the nutritional and visual properties of romaine lettuce (Lactuca sativa L.).
abstract: 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 beta-carotene, increased 37 and 80%, respectively. No differences were observed in lutein and beta-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.
authors.affiliation: Yuma Agricultural Research Center, Department of Plant Sciences, The University of Arizona, Yuma, Arizona 85364, USA. hyunjkim@kfri.re.kr
authors.forename: Hyun-Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Fonseca
authors.forename: Ju-Hee
authors.initials: JH
authors.lastname: Choi
authors.forename: Chieri
authors.initials: C
authors.lastname: Kubota
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Kwon
mesh_terms: D000383:Agriculture / Q000379:methods*; D002338:Carotenoids / Q000032:analysis; D018545:Lactuca / Q000737:chemistry* / Q000187:drug effects / Q000254:growth & development*; D010636:Phenols / Q000032:analysis; D054712:Salinity; D012965:Sodium Chloride / Q000008:administration & dosage / Q000032:analysis; D014867:Water / Q000032:analysis
chemical_list: D010636:Phenols; D014867:Water; D002338:Carotenoids; D012965:Sodium Chloride