EFFECT OF LIGHT REGIMEN ON YIELD AND FLAVONOID CONTENT OF WAREHOUSE GROWN AEROPONIC ERUCA SATIVA
Aero Farm Systems has developed a hydroponic module for growing leafy greens. One 400 watt high pressure sodium (HPS) light per 1.8 m2 growing area created poor light uniformity and required lamp heights that limited stackability of modules. Experimentation was conducted to determine if LED arrays could provide necessary light quality and irradiance without affecting plant yield and quality. Flavonoids were the chosen qualitative proxy due to their known nutraceutical properties. A custom computerized LED array (Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA) with an aeroponic growing system was used to provide differing intensity regimens of blue (460 nm, 8% of total light) and red (620 nm, 92% of total light) light to grow baby Arugula (Eruca sativa Astro). Four light irradiance regimens were compared to an HPS control (mean PPFD of 113 µmol m-2 s-1). The experiment was replicated over time for a total of 5 replicates. LED light regimens measured in µmol m-2 s-1, using a 24-h photoperiod from day 3 to 18, were L1, constant light at 150; L2, light decreasing from 225 to 75; L3, increasing from 75 to 275; and L4 increasing from 75 to 325. 25 g of seeds were spread across each 1 m2 test area and covered for 2 days. A commercial water soluble fertilizer was used with EC 2.0-3.0 dS m-1 maintained at pH 5.0-5.5. Canopy air temperature was 18-24°C. Harvestable fresh weight was not significantly affected by light treatment. However, some patterns were evident. All LED regimens, except L2, gave a harvestable fresh weight equal or greater than control; and L4 gave the high-est harvestable yields. Flavonoid content was greatest for L1, least for C, and was not significantly different for the L2-L4. Based on these results, LED arrays were found to be a suitable replacement to HPS, ideally with light levels increasing over devel-opmental time.
Mattson, N.S. and Harwood, E.D. (2012). EFFECT OF LIGHT REGIMEN ON YIELD AND FLAVONOID CONTENT OF WAREHOUSE GROWN AEROPONIC ERUCA SATIVA. Acta Hortic. 956, 417-422
LED, flavonoid, spectrum, HPS, irradiance