Contrary to Red, Blue Monochromatic Light Improves the Bioactive Compound Content in Broccoli Sprouts

Abstract

Broccoli sprouts are rich in health-promoting bioactive compounds. Their content depends on both cultivation light quality and temperature. However, these effects have been previously addressed in isolation. Here, the dual inputs of cultivation light quality [blue (B), red (R), mixture of R and B (R+B), mixture of R and UVA (R+UVA)] and air temperature (15, 19, and 23 °C) on determining growth, external quality, and the cotyledon and hypocotyl content of five major bioactive compounds were investigated. The carbohydrate status at harvest and postharvest ratio of variable to maximum fluorescence (Fv/Fm) were also assessed. Hypocotyl length was generally enhanced under monochromatic light (R or B) and elevated temperature. Total phenolic, total flavonoid, and glucoraphanin contents were generally higher in cotyledon as compared to hypocotyl. Hypocotyl anthocyanin, total phenolic, total flavonoid, and ascorbic acid contents were generally enhanced by R+B, and were decreased by R. Cotyledon content in these metabolites was generally stimulated by B, and reduced under R or R+UVA. Temperature affected metabolite content depending on the metabolite, organ, and light quality. Lower temperatures, R (23 °C) or R+UVA (15, 19, and 23 °C) were associated with decreased postharvest Fv/Fm. In conclusion, low cultivation temperature (<23 °C), as well as R or R+UVA ought to be avoided. Instead, B and R+B are suitable, with B being preferable, owing to better external quality and enhanced metabolite content in cotyledon which generally holds higher content than hypocotyl.

The Combination of Monochromatic LEDs and Elicitation with Stressors Enhances the Accumulation of Glucosinolates in Mustard Sprouts with Species-Dependency

“…Contrarily, in the work of Maina et al [ 31 ], both blue and red LEDs enhanced the accumulation of sinigrin in Ethiopian mustard, where especially the red LEDs were also effective in increasing the accumulation of 4-hydroxyglucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin (while decreasing the levels of glucobrassicin), in concordance with our results. However, we also found that the use of blue LEDs produced better results than red LEDs for black mustard sprouts, as previously determined, for example, in broccoli sprouts [ 25 ]. A significant positive effect of blue LEDs on the biosynthesis of aliphatic glucosinolates in broccoli sprouts has been related with the overexpression of the CYP79F1 and CYP83A1 genes that are involved in their biosynthesis pathway [ 43 ], which may be extended to other species.…”

“…Previous works have reported that the use of either monochromatic blue or red LEDs may affect several growth parameters in broccoli sprouts, but did not produce a biomass increase [ 24 , 25 ]. Neither the supplementation of warm-white light with blue or red LEDs (50 µmol m −2 s −1 ) was effective for increasing the biomass in baby-leaf lettuce [ 26 ].…”

“…One strategy that has proved to be successful for enriching Brassicaceae crops and sprouts in secondary metabolites is the application of exogenous elicitors, such as specific plant hormones [ 39 ], or their development under abiotic stressors, such as irrigation with saline solutions [ 40 ]. Growing these species under specific light conditions can modify the accumulation of metabolites as well [ 25 ]. In the current study, the effect that (i) differential lighting, (ii) saline irrigation, and (iii) the exogenous application of MeJA have on the biosynthesis and accumulation of glucosinolates in three mustard sprouts was tested.…”

Plants exposed to titanium dioxide nanoparticles acquired contrasting photosynthetic and morphological strategies depending on the growing light intensity: a case study in radish

“…5 ). The level of primary energy reserves has been earlier associated with prolonged postharvest longevity 22 , 37 . For instance, an increased content of soluble carbohydrates may support maintenance needs (by sustaining ATP synthesis), and protect membrane integrity (by scavenging reactive oxygen species) 22 , 37 .…”

“…As a sensitive indicator of photosynthetic performance, dark-adapted values of the maximum quantum yield of PSII (F v /F m ; equation and explanation in Table 3 ) were non-invasively recorded in leaves of each treatment 22 , 37 , 63 . Measurements were performed by using a portable imaging fluorometer (Handy FluorCam FC 1000-H, Photon Systems Instruments, Drásov, Czech Republic).…”