The Effect of Blue Light Dosage on Growth and Antioxidant Properties of Microgreens.

The effects of blue light-emitting diode (LED) light dosages on the growth and antioxidant properties of red pak choi (Brassica rapa var. chinensis 'Rubi' F1), tatsoi (Brassica rapa var. rosularis) and basil (Ocimum basilicum L. 'Sweet Genovese') microgreens were determined. The plants were grown within a controlled-environment growth chamber (21/ 17 ± 2 °C day/ night; 55 ± 5% relative air humidity) under five dosages (0%, 8%, 16%, 25%, 33%) of blue 447 nm in combination with red 638 nm, red 665 nm and far red 731 nm LEDs treatments (total PPFD ~ 302.5 µmol m-2 s-1; 16 h photoperiod). The influence of blue light dosage varied between microgreen species. The dosages of 16% and 33% led to significant lower hypocotyls and plant height of red pak choi, tatsoi and basil respectively. The highest concentration of ascorbic acid was determined in the tatsoi grown under 8% and in the red pak choi and basil under 16% blue light dosages. The tatsoi and basil showed the ability to accumulate more total phenols at 16-33% and the red pak choi at 8% blue light dosages. The similar trends on anthocyanin content and flavonols index were determined. The absence (0%) and the highest (33%) blue light dosage led to higher DPPH? radical scavenging activity in tatsoi and basil, but in pak choi it was significantly lower. [ABSTRACT FROM AUTHOR]