All plant parts of the Moringa oleifera can contain relevant concentrations of phytochemicals with health benefits. Plants grown in vitro allow pathogen-free plant material production and rapid propagation, and this technique is widely used to obtain secondary metabolites. This study analyzed how light spectrum quality affects growth, chlorophyll, and total phenolic content in M. oleifera plants grown in vitro. M. oleifera seeds were inoculated in MS medium supplemented with 3% sucrose and 0.7% agar and were stored under a controlled temperature, humidity and photoperiod. The light conditions tested were white fluorescent lamps (WFL) and light-emitting diodes (LED: 70% red + 30% blue), both standardized with a photon flux density of 58 μmol m-2s-1. Radiation emitted by WFL and LED did not influence stem germination, height, or diameter. However, WFL provided higher total chlorophyll levels. All plant parts germinated in vitro were analyzed via high-performance liquid chromatography with a diode-array detector (HPLC-DAD), and preliminary analyses revealed preferential synthesis of gallic acid derivatives in the leaves under LED radiation. For the total phenolic content, leaves under the LED and WFL irradiations showed 3.524 ± 0.054 and 3.805 ± 0.304 micrograms, respectively, of gallic acid equivalents per milligram of dry matter (μg GAE mg-1 DM). Light quality did not interfere with phenolic compound accumulation; however, it stimulated the preferential synthesis of gallic acid derivatives in leaves grown under LED radiation, and the evidence indicated that all evaluated organs synthesized nonpolar substances.

Sunflower (Helianthus annuus L.) is a relevant oilseed species used as feed in human and animal nutrition and in multiple industrial applications. However, oilseeds need to deal with the loss of vigor when used as a propagule, due to loss of seed physiological quality (viability and vigor) caused by deterioration events. We have evaluated in the present study the effects of seeds priming techniques (water, ascorbic acid, and sodium nitroprusside) on vigor, germination, antioxidant enzymes and membrane integrity of stored sunflower hybrid HELIO 251 seeds. Germination parameters showed that non-primed seeds (control) delayed germination in almost 72 h while all primed seeds germinated 100% in 24 h. Electrolyte leakage and malondialdehyde levels were higher in non-primed seeds indicating higher degree of membrane damage. An increase in the activity of catalase and ascorbate peroxidase was also observed after 8 h of imbibition of primed seeds compared to non-primed seeds. Regarding superoxide dismutase, there was no significant differences between treatments after 8 h of imbibition, whereas the highest activity was after 24 h of imbibition in non-primed seeds. Therefore, it can be concluded priming with ascorbic acid or sodium nitroprusside exhibited better performance in germination of stored sunflower seeds, probably resulting from lower accumulation of reactive oxygen species and consequent reduced oxidative damage due to an efficient antioxidant enzyme system.