Interactions between nutrient types and soil hydrological properties on yield and quality of Pinellia ternata, a medicinal plant

Cultivation is one of the typical approaches to enhance supply of medicinal plants, such as Pinellia ternata, for the rising popularity of herbal medicine. However, effects of nutrient and its interaction with soil hydrological behaviour for the growth of P. ternata are yet to be revealed. This study aims to examine the effects of nutrient types on soil hydrological properties as well as yield and active ingredient of P. ternata. Forty-eight replicates of P. ternata were grown in silty sand supplied with nitrogen (N), phosphorus (P), potassium (K), and combinations of them. A control was also prepared without nutrient supplied. Soil properties including bioavailable nutrients, heads of osmotic and matric suctions, and water retention were examined. Plant characteristics, particularly biomass and succinic acid of bulbil (yield and quality of P. ternata), were determined and analysed with linear correlation. For single nutrient, P gave the highest bulbil biomass, which was 43% higher than the control. Among multiple nutrients, only PK condition showed an increase in bulbil biomass, which was double that of the control. Since total head and soil-water retention decreased with an increase in nutrient types, higher root biomass in P and PK compensated such effects. It revealed that P governs bulbil biomass of P. ternata. Moreover, succinic acid in N was 9 times higher than control and the highest among all conditions. This implied that N is a key to promote succinic acid in P. ternata. Both findings are supported by strong linear correlation(r > 0.7). This study has identified nutritional benefits on improving yield and quality (i.e., succinic acid) of P. ternata. It also highlights that besides soil fertility, nutrient effects on soil hydrological properties should be considered in cultivation practice for growing P. ternata and potentially other valuable medicinal plants.