ASHS 2024 Conference

Efficient nutrient management is the key to successful hydroponic production. However, there is a lack of comprehensive research regarding the optimal electrical conductivity (EC) levels for various leafy green vegetables in recirculating hydroponic cultivation. To address this research gap, we experimented with different EC levels using the nutrient film technique (NFT) hydroponic system in a greenhouse with three replications during the fall (air temp: 24.22°C, RH: 31.2%) winter (air temp: 15.5 °C, RH: 73.3%) and early spring (air temp: 13.7 °C, RH: 72.4%). The experiment was conducted using three different EC levels (1.2, 1.8, and 2.4 mS/cm) for six different leafy green vegetables kale (Brassica oleracea) ‘Winter bor F1’ and ‘Toscano’, swiss chard (Beta vulgaris), basil (Ocimum basilicum) ‘Prospera® Compact DMR (PL4)’ and ‘large leaf’ and red malabar spinach (Basella alba). Our results showed that, during the fall, the shoot fresh weight of the ‘Winter bor F1’ increased by 13.1 % in EC 2.4 compared to EC 1.2 and that of Swiss chard increased by 8.3-20.6% in EC 2.4 compared to EC 1.2 and 1.8 while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 13.1-13.9 % in EC 1.8 compared to EC 1.2 and 2.4. In contrast during the winter, the shoot fresh weight of ‘Toscano’ kale, ‘Winter bor F1’ kale, and ‘large leaf’ basil increased by 11.2-17.8%, 18.9-20.8%, and 13.2-14.7%, respectively in EC 2.4 compared to EC 1.2 and 1.8, while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 19.2 % in EC 1.2 compared to the EC 2.4. However, during the early spring, only the shoot fresh weight of ‘Winter bor F1’ kale in EC 1.8 was increased by 10.0 % compared to EC 1.2, while the plant height and fresh shoot weight of large leaf basil was increased slightly by 3.1-5.6% in EC 2.4 compared to EC 1.2. In summary, this experience suggested that ’Winter bor F1’ kale performed best in EC 2.4 during the fall and winter seasons but grew best in EC 1.8 during the early spring. In addition, the 2.4 mS/cm proved the optimal EC level for Swiss chard during the fall, ‘Toscano’ kale during the winter, and ‘large leaf’ basil during the spring. The results from this experiment identify optimal EC levels of vital leafy vegetables in Kansas for different seasons, aiding Kansas growers in reducing nutrient waste and enhancing leafy vegetable production.