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Manipulation of contents of nitrate, phenolic acids, chlorophylls and carotenoids in lettuce (Lactuca sativa L.) via contrasting responses to nitrogen fertilizer when grown in a controlled environment

Lookup NU author(s): Othman Qadir, Dr Mario Siervo, Emeritus Professor Chris SealORCiD, Dr Kirsten BrandtORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2017.

For re-use rights please refer to the publisher's terms and conditions.


This study aimed to use different nitrogen fertilizer regimes to produce Butterhead lettuce with such large differences in nitrate content that they could be used as treatment and placebo to study the effect of inorganic nitrate on human health. Plants were grown under controlled conditions at 27/23°C day/night with a relatively low Photosyntetically Active Radiation (PAR) of 150μmol m-2 s-1 for 14 hours day-1 and nitrogen supplies ranging from 26 to 154ppm N as ammonium nitrate in the fertigation solution. This resulted in contrasting high (~1078 mg nitrate 100g-1 FW) or low (~6 mg 100g-1) nitrate contents in the leaves. Contents of carotenoids and chlorophylls in fresh weight did not differ significantly between highest and lowest N-supply levels. However, increased nitrogen supply reduced contents of phenolic compounds from 154 to 22mg 100g-1 FW, dry matter content from 8.9 to 4.6% and fresh weight per plant from 108.52 to 47.57 g/plant FW (all P<0.001). So while fertilizer treatments can provide lettuce with substantially different nitrate contents, maintaining similar pigment contents (color), they also strongly influence the contents of phenolic acids and flavones.

Publication metadata

Author(s): Qadir O, Siervo M, Seal CJ, Brandt K

Publication type: Article

Publication status: Published

Journal: Journal of Agricultural and Food Chemistry

Year: 2017

Volume: 65

Issue: 46

Pages: 10003-10010

Print publication date: 22/11/2017

Online publication date: 23/10/2017

Acceptance date: 07/08/2017

Date deposited: 24/10/2017

ISSN (print): 0021-8561

ISSN (electronic): 1520-5118

Publisher: American Chemical Society


DOI: 10.1021/acs.jafc.7b03675


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