Effect of light quality and ionising radiation on morphological and nutraceutical traits of sprouts for astronauts’ diet.

Sprouts are nutritious food, easy to produce even in extra-terrestrial platforms, where the exposure to ionising radiation can alter their morpho-anatomical traits and phytochemical content. The aim of this study was to evaluate whether sprout production under specific light wavelengths can mitigate the negative effects of radiation and/or stimulate the induction of hormesis. Germinated seeds, with actively proliferating cells, of mung bean were irradiated with increasing X-ray doses (0–20 Gy) and then incubated in controlled conditions under four different light regimes: dark (D), white light (W), red light (R), red-blue light (RB). Morpho-anatomical development of the sprouts was investigated through light-microscopy and their content of flavonoids and isoflavones was quantified by HPLC. Two significant conclusions emerged: 1) RB wavelength induces hormesis by stimulating the production of antioxidant compounds; 2) R wavelength offsets the harmful effects of radiation on morpho-anatomical traits, even at the highest X-ray dose.