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Abstract
The release of two new potato (Solanum tuberosum L.) cultivars with different maturing characteristics, Haryeong and Jayoung, necessitates the development of appropriate electrical conductivity (EC) recommendations for the nutrient solutions used in hydroponic seed potato production. The two cultivars, along with the standard cultivar, Superior, were grown with four nutrient solutions differing in EC (0.6, 1.2, 1.8, and 2.4 dS m^sup -1^). The EC of nutrient solution did not influence photosynthetic rate (Pr) or water use efficiency (WUE) of leaves, whereas it affected total chlorophyll content, transpiration rate (Tr), and stomatal conductance (Sc) in some cultivars, highest at 0.6 dS m^sup -1^ EC for Tr and Sc, and lowest at the same EC for total chlorophyll content. The nutrient content of shoots was significantly affected by ECs of the nutrient solution. The total-N content was higher in 2.4 dS m^sup -1^ EC, whereas a lower P, Ca, and Mg content was measured in plants grown at the same EC. Plants grown with a lower EC had inhibited shoot and stolon growth and earlier tuber formation compared to those grown with higher ECs. For the 0.6 dS m^sup -1^ EC treatment, tubers were first observed on days 40, 50, and 52 for cvs. Superior, Haryeong, and Jayoung, respectively. For higher EC treatments, tubers were observed 5 to 6 days later, particularly for the new cultivars. At harvest, the number of tubers produced from Superior and Jayoung plants was not affected by EC, whereas those of Haryeong increased at 1.8 dS m^sup -1^ EC. The results suggest that potato cvs. Superior and Jayoung are able to grow at a wide range of solution EC levels, but that the new cultivar Haryeong needed optimal management of solution EC at 1.8 dS m^sup -1^ to yield higher tuber production under an aeroponic cultivation system.[PUBLICATION ABSTRACT]