Selenium, Iodine, and Supplementary Blue Light Enriched Fenugreek ( Trigonella foenum-gracum L.) in Terms of Biochemical Quality, Mineral Uptake, and Trace Elements Accumulation in a Hydroponic System

This study was conducted to test the hypothesis that supplementary blue light, feeding with selenium and iodine can improve the biochemical quality, macro- and micro-elements in the edible parts of fenugreek and, with the accumulation of selenium and iodine in plant tissue, the production of a biofortified crop. For this purpose, the effect of selenium (0, 2, and 4 mg L −1 ), iodine (0, 2, and 4 mg L −1 ), and supplementary blue light (no-blue light and blue light treatment) was tested in the form of a three-way factorial experiment based on a completely randomized design. The results showed that supplementary light treatment and feeding with iodine (2 mg L −1 ) increased the content of phenol, total protein, and vitamin C. The interaction of iodine (4 mg L −1 ) and blue lighting increased the content of iron and vitamin C. Irrespective of lighting conditions, iodine improved the iodine content. The combination of blue light and 4 mg L −1 selenium increased the nitrogen, iron, phosphorus, and magnesium compared to other treatments. The best conditions for the accumulation of selenium were a combination of blue light and 4 mg L −1 of selenium. Increasing the concentration of feeding with iodine and selenium was beneficial for the accumulation of flavonoids, carbohydrates, protein, and vitamin C. Although the triple effects of feeding with selenium and iodine under blue supplementary light affected some traits, it is difficult to elicit obvious results from them. In general, the application of iodine and selenium (4 mg L −1 ) under blue light is recommended to achieve the study objectives.