Effects of Node Position and Electric Conductivity of Nutrient Solution on Adventitious Rooting of Nasturtium (Tropaeolum majus L.) Cuttings

Nasturtium is a popular herbal plant, widely cultivated as culinary and medicinal plants all over the world. However, the seed propagation of nasturtium is inefficient, and in-vitro propagation is sophisticated and high-cost. In this study, the cutting propagation method was employed to produce nasturtium seedlings. We aimed to determine the optimal conditions for cutting propagation of nasturtium seedlings by investigating the effects of node position and electric conductivity (EC) of nutrient solution on the root formation of the cuttings. Cuttings from five node positions (apical bud, 2nd node, 3rd node, 4th node, and 5th node) were subjected to water and five EC (1.0, 2.0, 3.0, 4.0, and 5.0 dS m⁻¹) treatments with a hydroponic cultivation system in a plant factory. Results showed that all cuttings rooted successfully within two weeks. The cuttings from the apical bud position rooted earliest and produced the most roots regardless of EC level. Cuttings from other node positions produced longer roots and heavier root fresh and dry weights than those from the apical bud position. The cuttings under EC of 1.0 dS m⁻¹ had the greatest root number, the longest root length, and the heaviest root fresh and dry weights regardless of node positions. The EC of 1.0 dS m⁻¹ is considered the best condition for nasturtium cuttings for the range of EC tested in this study, and the cuttings from all the five node positions can be used as seedling materials.