Department of Plant Sciences

The yield and mineral element concentration of beetroot (Beta vulgaris ‘Bulls Blood’) was determined in a closed nutrient-recirculating ‘Nutrient Film Technique’ (NFT) hydroponic experiment. Seedlings were grown and harvested 42 days after transfer into NFT system (DAT), either with a commercial hydroponic fertilizer or a non-hydroponic soluble fertilizer containing in mg liter-1: 108 nitrogen (N) and 12 calcium (Ca) (N1Ca1), or 200 N and 66.7 Ca (N2Ca2), respectively. Nutrient source had no significant effect (p=0.05) on leaf fresh and dry weight (LFW, LDW) or root dry weight (RDW) (g/plant) of beetroot. Whereas, edible root fresh weight (RFW) was significantly (p=0.0308) increased at N2Ca2 compared with N1Ca1, root dry weight ratio (RDWR; RFW/RDW) was greater (p=0.0004) at N1Ca1 than N2Ca2. The greater RFW at N2Ca2 corresponded with significantly higher (p=0.05) leaf concentrations of Ca, magnesium (Mg), manganese (Mn), molybdenum (Mo), aluminum (Al) and sodium (Na), but not zinc (Zn). Nutrient source had no affect leaf N, phosphorus (P), potassium (K) and sulfur (S) concentration. Although leaf macro- and micronutrient concentration were variable, all the essential elements except Ca, iron (Fe) and B (at N1Ca1) were either within or above the sufficiency range for beetroot. These observations suggest that low tissue concentration of Ca and B contributed to the lower RFW at N1Ca1 compared with N2Ca2. Sufficiency in Ca and B content should be a major consideration in nutrient source selection and management in NFT hydroponic culture of beetroot.