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To investigate the potentiality of Eruca sativa (rocket) to be enriched in selenium (Se) and, thus, to promote human health through consumption, a pot experiment was designed. Two rates, 5 and 10 mg/kg soil, of either selenite or selenate sodium salts were applied to appropriate pots, each filled with 1 kg of calcareous soil. Rocket seedlings were transplanted and grown in these pots, and to half of the pots the biostimulant Actiwave was added. Twelve weeks later, the plants were harvested and Se concentrations determined in shoots and roots. Plant growth characteristics were measured and plants biometrics were assessed by soil plant analyses development (SPAD), normalised difference vegetation index (NDVI) and normalised difference red edge (NDRE). Sulfur (S) and phosphorus (P) concentrations in plant samples were also determined to discuss possible interactions among the three elements. The highest Se concentration of 1070.5 mg/kg dry weight (DW) was observed for the high selenate rate without biostimulant, placing rocket in the group of Se hyperaccumulator plants. Toxic effects were recorded for the plants that received the high selenate rate, whereas no toxicity symptoms were observed for either selenite rate. According to Se concentrations in controls, biostimulant application significantly suppressed Se uptake and significantly increased S and P uptake. The same negative biostimulant effect on Se concentration in plants was clear in selenate treatments. When the results were expressed as total uptake (mg/pot), positive correlations among Se, S and P were found for selenate treatments, whereas for selenite treatments, the opposite was observed. Impressively, 1.6 mg Se/pot on a DW basis was accumulated in rocket shoots in the low selenate-rate without biostimulant treatment, corresponding to approximately 30% of the added 5 mg of selenate. Selenium is an essential element for humans and animals. This study reports on the enrichment of selenium in rocket plants and the results showed that when selenium is added as selenate, the plants accumulate high amounts of selenium. Although further research is needed to optimise the selenate application rate so as to avoid leaching and subsurface water contamination, it seems feasible to produce a vegetable of high nutritional value for human consumption without negatively affecting the environment. [ABSTRACT FROM AUTHOR]

Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of either selenate or selenite and for the effect of 5% w/w biochar addition. Lettuce seedlings were grown in pots containing 1 kg of a calcareous soil. Twelve weeks later, the plants were harvested and selenium (Se), phosphorus (P), and sulfur (S) concentrations were determined in heads and roots. Plant growth characteristics were measured and plant biometrics were assessed by NDVI, NDRE, and SPAD measurements. The highest Se concentration of 315.19 mg kg−1 D.W. and the highest amount of Se taken up by plants (950.5 μg/pot) were observed for the low selenate rate with biochar. The corresponding values for selenite treatments were an order of magnitude lower. Although in general, minor to severe toxicity symptoms occurred with selenium application in no biochar treatments (except selenite low rate), the addition of biochar secured plant growth and increased S and P concentrations in plants, regulating Se uptake by plants at high selenite rate and allowing maximum plant uptake at the low selenate rate. To propose an appropriate Se fertilization rate, the fate of excess selenates in the soil environment should be examined and experimentation under soil conditions is necessary. [ABSTRACT FROM AUTHOR]