Effects of drought stress on growth and flavonoid accumulation of fish mint (Houttuynia cordata Thumb.)

Fish mint (Houttuynia cordata Thumb.) is a popular medicinal plant grown primarily because of its pharmacological values. Drought stress has on the relationship between growth and physio-biochemical changes, especially flavonoid content. The impacts of various drought stress conditions on the fish mint development were investigated, including 85% of field capacity (FC), 75% FC, 65% FC and 55% FC in 14, 21 and 28 days. Agronomic, physiological and biochemical parameters during the growth of fish mint plants under drought stress conditions were assessed. According to the results of variance analysis, drought stress results in a considerable drop in the measured parameters (shoot height, leaf number, leaf area and fresh weight). Similarly, all of the above-mentioned parameters were also decreased with increasing the number of drought days. Furthermore, drought period and level caused a drop in respiration, photosynthetic rate, chlorophyll and starch content. The concentration of carotenoids and flavonoids, on the other hand, increased dramatically as drought stress periods and levels increased. In comparison to the control, the drought treatment (65% FC) in 7 days maintained the growth rate and increased flavonoid accumulation from 2.42 mg to 3.04 mg. These findings might give a scientific foundation for growing fish mint plants under drought stress to boost flavonoid content