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The influence of substrate moisture and different dosages of UV-B radiation on spinach antioxidant phytochemical constituents was studied. Spinach (Spinacia oleracea L.) cv. 'Andromeda H' and 'Matador' were the objects of this study. Experiment was conducted in closed growth chambers of controlled environment at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Plants were placed in different growth chambers at 18/13°C day/night temperature and 12 h photoperiod. High-pressure sodium lamps (SON-T Agro, Philips) were used for illumination (150 µmol m-2 s-1). Spinacia oleracea plants after 21 days for germination were grown in normal (~40%) and drought (<10%) substrate. After 7 days substrate moisture influence plants were exposed to 0 kJm-2 day-1, 1 kJm-2 day-1 and 2 kJm-2 day-1, UV-B for 1 day. Analyses were made after 8-days of substrate moisture and UV-B radiation exposure. UV-B radiation (290-320 nm) was provided by UV-B fluorescent tubes (TL 40W/12 RS UV-B Medical, Philips). Different combinations of investigated factors had a significant influence on changes of spinach physiological indices. The lack of substrate moisture reduced the leaf area, fresh and dry biomass accumulation in the investigated species spinach, but under drought conditions increased accumulation of chlorophylls a, b and carotenoids. Spinaches of both species exposed to drought conditions and UV-B radiation have accumulated a larger amount of phenolic compounds and ascorbic acid, depended on their species and UV-B dose. [ABSTRACT FROM AUTHOR]

The influence of substrate moisture and different dosages of UV-B radiation on spinach antioxidant phytochemical constituents was studied. Spinach (Spinacia oleracea L.) cv 'Andromeda H' and 'Matador' were the objects of this study. Experiment was conducted in closed growth chambers of controlled environment at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Plants were placed in different growth chambers at 18/13°C day/night temperature and 12 h photoperiod. High-pressure sodium lamps (SON-T Agro, Philips) were used for illumination (150 µmol m-2 s-1). Spinacia oleracea plants after 21 days for germination were grown in normal (~40%) and drought (<10%) substrate. After 7 days substrate moisture influence plants were exposed to 0 kJm-2 day-1, 1 kJm-2 day-1 and 2 kJm-2 day-1, UV-B for 1 day. Analyses were made after 8-days of substrate moisture and UV-B radiation exposure. UV-B radiation (290-320 nm) was provided by UV-B fluorescent tubes (TL 40W/12 RS UV-B Medical, Philips). Different combinations of investigated factors had a significant influence on changes of spinach physiological indices. The lack of substrate moisture reduced the leaf area, fresh and dry biomass accumulation in the investigated species spinach, but under drought conditions increased accumulation of chlorophylls a, b and carotenoids. Spinaches of both species exposed to drought conditions and UV-B radiation have accumulated a larger amount of phenolic compounds and ascorbic acid, depended on their species and UV-B dose. [ABSTRACT FROM AUTHOR]