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 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 and dry matter content from 8.9 to 4.6% (both 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.
... B 176 (3,4-Dicaffeoylquinic acid), Isochlorogenic acid C (4,5-Dicaffeoylquinic acid), Cichoric acid 177 (Dicaffeoyltartaric acid), Caftaric acid (Caffeoyltartaric acid) were purchased from Biopurify 178 Phytochemicals Ltd, Rutin ...
