Characterization of Bean Seeds, Germination, and Phenolic Compounds of Seedlings by UV-C Radiation

We quantitatively evaluate the effects of UV-C radiation on bean seeds Oti (Phaseolus vulgaris), their germination and phenolic compounds of seedlings, by means of photoacoustic spectroscopy and scanning electron microscopy. It is shown that (i) The photoacoustic signal produced by the bean seeds exposed to UV-C radiation during 15 min, reduces from 0.24 to 0.10 mV for the wavelengths of 295 and 340 nm, as a result of their degradation. This significant reduction of 58.3% decreases, but keeps over 50% for other spectral UV wavelengths within the interval (270–400 nm). (ii) As the UV-C radiation time increases from 2 to 15 min, the morphological changes at the surface of the bean seeds exhibit micro-holes and detachment of the cotyledon sclereids. (iii) There are no significant statistical differences in the variables of germination, dry weight, and seedling length, for exposure times up to 15 min. (iv). The phenolic acids and flavonoids of the bean seedlings of seeds treated by UV-C for different exposure times (0, 2, 5, 10, and 15 min) display significant statistical differences (P ≤ 0.05) in both roots and foliage. For both the roots and foliage, the highest concentration of phenolic acids is observed at 10 and 15 min, while for root flavonoids, it appears at 5 and 15 min.