Abstract:The objective of this study was to evaluate the effect of the light emitting diode (LED) spectra on the antioxidant properties of sprouted wheat (Triticum aestivum L.), radish (Raphanus sativus L.), and lentil (Lens esculenta Moenh.) seeds. Lighting experiments were performed under controlled conditions (PPFD -100 µmol m -2 s -1 ; 12 h photoperiod; 27°C). The LED conditions used were: L1 -638 nm; L2 -455 nm, 638 nm, 669 nm, 731 nm (basal components); L3 -basal + 385 nm; L4 -basal + 510 nm and L5 -basal + 595 nm. Wheat and lentil sprouts were shown to accumulate less phenolic compounds and were more sensitive to light spectral differences when compared to radish sprouts. The antioxidant properties and contents of antioxidant compounds in seeds germinated in the dark were significantly lower than LED treated seeds. The higher content of total phenols and significant increase in alpha-tocopherol and vitamin C concentration resulted in altered DPPH free-radical scavenging capacity. Therefore we conclude that the LED spectra, based on basal components supplemented with green (510 nm) light can improve the antioxidant properties of sprouted seeds of lentil and wheat. The highest antioxidant properties of radish seeds were caused by radiation with supplemental amber (595 nm) light.

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Effects of short-term ozone (O 3 ) fumigation on radish (Raphanus sativus L.) plants were examined in growth chambers under controlled environment conditions. Plants were exposed to 0 μg/m 3 (reference), 80 μg/m 3 , 160 μg/m 3 and 240 μg/m 3 O 3 concentrations for 7 h per day for five days. Day/night temperature was 21ºC/14ºC and photoperiod 16 h. Chlorophyll content was evaluated spectrophotometrically. Chromatographic analysis of saccharides was also undertaken. The results showed that elevated O 3 inhibited the growth of radish rhizocarps, net assimilation rate and biomass accumulation. O 3 induced leaf desiccation, necrosis and premature senescence, but a typical reaction of plants to O 3 stress was the rapid regeneration of new leaves. O 3 inhibited accumulation of carotenoids more than chlorophylls. The higher photosynthetic pigment content in newly generated radish leaves may be regarded as an adaptation of the photosynthetic system to O 3 . Leaf saccharide metabolism and incorporation depended on O 3 concentration. Rapid regeneration of new leaves and increased content of photosynthetic pigments is the typical reaction of radish plants to O 3 stress.