Manipulation of Contents of Nitrate, Phenolic Acids, Chlorophylls, and

University of Sulaimani, Sulaymaniah 46001, Iraqi Kurdistan Region. J. Agric. Food Chem. , 2017, 65 (46), pp 10003–10010. DOI: 10.1021/acs.jafc...
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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. Othman Qadir, Mario Siervo, Christopher John Seal, and Kirsten Brandt J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b03675 • Publication Date (Web): 23 Oct 2017 Downloaded from http://pubs.acs.org on October 25, 2017

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Journal of Agricultural and Food Chemistry

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Manipulation of contents of nitrate, phenolic acids, chlorophylls and

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carotenoids in lettuce (Lactuca sativa L.) via contrasting responses to

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nitrogen fertilizer when grown in a controlled environment.

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Othman Qadir1, 2, *, Mario Siervo1, Chris J. Seal1, Kirsten Brandt1

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Newcastle upon Tyne, NE4 5PL, UK.

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Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University,

Food Science and Human Nutrition Dept., Faculty of Agricultural Sciences, University of Sulaimani,

Sulaymaniah, 46001, Iraqi Kurdistan Region.

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* Corresponding author: +44 7925417105, [email protected]

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ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

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ABSTRACT

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This study aimed to use different nitrogen fertilizer regimes to produce Butterhead lettuce with such

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large differences in nitrate content that they could be used as treatment and placebo to study the effect

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of inorganic nitrate on human health. Plants were grown under controlled conditions at 27/23°C

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day/night with a relatively low Photosyntetically Active Radiation (PAR) of 150μmol m-2 s-1 for 14

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hours day-1 and nitrogen supplies ranging from 26 to 154ppm N as ammonium nitrate in the

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fertigation solution. This resulted in contrasting high (~1078 mg nitrate 100g-1 FW) or low (~6 mg

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100g-1) nitrate contents in the leaves. Contents of carotenoids and chlorophylls in fresh weight did

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not differ significantly between highest and lowest N-supply levels. However, increased nitrogen

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supply reduced contents of phenolic compounds from 154 to 22mg 100g-1 FW, dry matter content

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from 8.9 to 4.6% and fresh weight per plant from 108.52 to 47.57 g/plant FW (all P