The Electrical Conductivity of Nutrient Solution Influenced the Growth, Centellosides Content and Gene Expression of <i>Centella asiatica</i> in a Hydroponic System

<i>Centella asiatica</i> is a herbaceous plant containing medicinal and cosmetic properties: anti-bacterial, anti-aging, memory enhancing and wound healing. The lack of information impedes the development of suitable growth conditions for <i>C. asiatica</i> in the hydroponic system. Maintaining proper electrical conductivity (EC) of a nutrient solution is considered crucial for plant growth and the accumulation of bioactive compounds in a plant grown in hydroponics. This study aimed to investigate an optimal EC that enhances the growth of <i>C. asiatica</i> and its centellosides content. Seedlings were grown in commercial nutrient solution and treated with four different strengths of EC (0.6, 1.2, 1.8 and 2.4 indicated T₁, T₂, T₃ and T₄, respectively) under controlled environment conditions. Our results demonstrate that the number of leaves, leaf area, number of runners, shoot fresh weight and shoot dry weight were significantly increased in T₂ among the treatments. However, these growth parameters were lowest in T₄. Furthermore, the content of asiaticoside, madecassoside, asiatic acid and madecassic acid was the highest in plants that were treated with T₂. The expression of centelloside biosynthesis-related genes is also affected by the strength of the nutrient solution. A positive correlation was observed between the number of leaves, leaf area and centellosides content. This study provides valuable background on optimal EC content in the nutrient solution in a hydroponic system with enhanced centellosides content to leverage the <i>C. asiatica</i> production.