Red light is effective in reducing nitrate concentration in rocket by increasing nitrate reductase activity, and contributes to increased total glucosinolates content

Signore, A., Bell, L. ORCID: https://orcid.org/0000-0003-2895-2030, Santamaria, P., Wagstaff, C. ORCID: https://orcid.org/0000-0001-9400-8641 and Van Labeke, M.-C. (2020) Red light is effective in reducing nitrate concentration in rocket by increasing nitrate reductase activity, and contributes to increased total glucosinolates content. Frontiers in Plant Science, 11. 604. ISSN 1664-462X doi: 10.3389/fpls.2020.00604

Abstract/Summary

Rocket cultivation is increasing to supply the expanding ready-to-eat market because of its unique taste, but crops are often over fertilized to avoid nitrogen deficiencies. This leads to nitrate accumulation in leaves, and the products of their degradation (nitrites and nitrosamines) have been related to several health problems. Nitrate concentrations in rocket and other leafy vegetables are subject to limits by the EU legislation, yet rocket holds a great nutritional value. Degradation products of glucosinolates (isothiocyanates) have been consistently linked with benefits to human health. We investigated the influence of nitrogen application (1 and 8 mM), species (Eruca sativa (L.) Cav. and Diplotaxis tenuifolia (L.) DC.) and light spectrum (full spectrum, red, blue and red+blue) on the nitrate concentration, nitrate reductase activity and glucosinolate content of rocket grown in a soil-less system. Red light decreased the nitrate concentration with respect to the blue spectrum (4,270 vs 7,100 mg·kg-1 of fresh weight, respectively), but such reduction was influenced by the species and the nitrogen level (significantly higher in D. tenuifolia and with the higher concentration of N). The nitrate reductase activity increased under red light in D. tenuifolia, with the lower N concentration. Rocket is known to contain several health-promoting compounds mainly antioxidants and glucosinolates, as secondary metabolites that act as part of plant defense mechanisms. The total content of glucosinolates was mainly affected by the species (D. tenuifolia showed the highest concentrations). Our results will help growers to tailor light spectra with the aim of reducing nitrate concentration and to remain within EU legislative limits, without any detrimental influence on other qualitative parameters in rocket.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/90259
Identification Number/DOI	10.3389/fpls.2020.00604
Refereed	Yes
Divisions	Interdisciplinary Research Centres (IDRCs) > Institute for Food, Nutrition and Health (IFNH) Life Sciences > School of Agriculture, Policy and Development > Department of Crop Science Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Human Nutrition Research Group
Publisher	Frontiers
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