Application of photo-selective films to manipulate wavelength of transmitted radiation and photosynthate composition in red beet (Beta vulgaris var. conditiva Alef.)

BACKGROUNDInterest is increasing around both the use of plants as functional foods and the agronomic techniques which can increase nutrients and phytochemicals. Nevertheless, little research has focused on the effects of light on accumulation of active compounds in root storage organs. Red beet was treated with RED (red/far red ratio: 1.29; transmitted photosynthetically active radiation: 66.9%) and GREEN (red/far red ratio: 0.43; transmitted photosynthetically active radiation: 25.8%) photo-selective films and changes in nutrients and biomass accumulation were measured. RESULTSPlants subjected to GREEN treatment had less dry weight accumulation both in storage roots (68%) and leaves (42%); moreover, soluble and structural carbohydrate concentration in roots was increased, as were the K, Mg and Zn concentrations (40.08, 2.95 and 0.023mgg(-1) fresh weight, respectively). Conversely, GREEN lowered total phenolic concentration (0.33 vs. 0.47mgg(-1) fresh weight) and antioxidant activity (0.65 vs. 0.94 mu m Trolox equivalents g(-1) fresh weight) compared to CONTROL. Total pigment concentration was reduced by 20% and 48% with RED and GREEN treatments, respectively. CONCLUSIONRed beet showed a strong plasticity in its adaptation to light availability. Some macronutrients (fiber, sugars, minerals) can be concentrated in roots by modifying the amount and quality of the light, principally with GREEN photo-selective films. (c) 2013 Society of Chemical Industry