Meeting Abstract
Kale (Brassica oleracea var. sabellica) is a popular and nutritious vegetable in part because of its high antioxidant content. However, kale is often grown in greenhouses or indoor hydroponic farms using light sources containing no UV radiation despite the fact that UVR stimulates antioxidant production as part of stress and developmental responses which include changes in pigmentation, leaf anatomy, and biomass. The effects of UV supplementation were tested on two varieties of kale to assess the potential benefits and drawbacks of UV treatment on greenhouse-grown kale. After three days of UV-treatment, one of the varieties showed a 29% increase in antioxidant content while the other showed no significant difference. After seven and fourteen days of UV treatment, the UV stress response was characterized through biomass, UV absorbance spectra, UV reflectance spectra, and leaf chlorophyll and flavonoid content. Both varieties of kale displayed a pattern of short-term stress and long-term acclimation: at seven days, UV-treated plants were smaller than untreated plants, had lower UV absorbance and reflectance, and had higher chlorophyll and UVA-absorbing-flavonoid content. At fourteen days, most of these differences were smaller or insignificant. For example, after seven days of UV exposure, the UV-treated Premier kale was 21% smaller than its untreated counterparts, but after fourteen days of exposure, there was no significant difference between the two groups. Therefore, while UV-supplemented plants are initially smaller but more nutritious than unsupplemented plants, these effects lessen after two weeks of consecutive treatment as plants acclimate to UV exposure.
