The Effects of Ultraviolet Radiation on Pigment Production, Growth, and Photochemical Efficiency in Allium spp

In the 1970s, a push for research on the effects of ultraviolet (UV) radiation on food crops began. Since that time, multiple agricultural and horticultural crops have been studied with results showing that the morphological and physical reactions are species dependent. The purpose of these studies to determine how increasing UV radiation affects Allium fistulosum L. (scallion onions) and Allium tuberosum Rottl. (garlic chives), and how UV radiation affects 16 cultigens of A. fistulosum. The effects of UV radiation were determined by shoot height, fresh weight, carotenoid and chlorophyll pigment concentrations, and photochemical efficiency (F_v/F_m). The scallions showed decreases in shoot height and fresh weight in both studies, while the chives showed increases in both shoot height and fresh weight. High performance liquid chromatography showed changes in concentrations of nutritionally important carotenoids like lutein and the xanthophyll carotenoids were noted, while â-carotene concentrations did not change. Changes in chlorophyll a and b concentrations and ratios were also found. Changes in the xanthophyll cycle were found in the scallion cultigens, indicating irradiation stress. The scallion cultigens were found not to differ much between UV radiation treatments, but there were significant differences among the cultigens. To our knowledge, this is the first study to date that has examined the effects of UV radiation on Allium carotenoids.