The medicinal species of Carla (Momoradica charantia) is one of the medicinal plants in Cucurbitaceae family, which has shown signifcant effects on the control of diabetes, blood pressure, high cholesterol and liver failure due to its valuable alkaloid and glycosidic compounds. In order to investigate the effect of different strengths of Hoagland’s nutrient solution and different levels of sodium silicate on yield components, biochemical characteristics and photosynthetic pigments of the medicinal plant Carla under hydroponic conditions, a factorial experiment in the form of a completely randomized design with three replications was carried out in the Department of Medicinal Plants of Arak University. The frst factor included the concentrations of nutrient solution at four levels (¼, ½, 1 and 2 strength of Hoagland’s nutrient solution) and the second factor included sodium silicate spraying at four levels (0, 50, 100 and 150 mg L− 1) taken from the source of sodium silicate. The results showed that different strengths of Hoagland’s nutrient solution and different concentrations of sodium silicate had a signifcant effect on all growth and morphological traits. The results of the experiment showed an increase in the number of flowers and fruits in double strength Hoagland concentration compared to the control (full strength), and the lowest amounts of these traits were observed at ¼ strength Hoagland concentration. In addition, the maximum numbers of flowers and fruit, fruit diameter, fruit length, and fruit weight were obtained at concentration of 100 mg L− 1 sodium silicate, and the minimum values of these traits were recorded at ¼ strength Hoagland’s solution. The highest amounts of chlorophyll b and a were seen in double strength Hoagland’s solution and the lowest amounts were seen in ¼ strength Hoagland. Moreover, the amount of carotenoid was the highest in ¼ strength Hoagland and the lowest in double strength Hoagland. The maximum and minimum values of chlorophyll b and a were obtained at concentrations of 150 and 0 mg/kg sodium silicate, respectively. In general, it was found that double strength Hoagland was more effective than other concentrations on yield components and morphological parameters, and flowering and fruit harvesting times were also reduced in the mentioned treatment. On the other hand, sodium silicate at 100 and 150 mg L− 1 had more obvious effects on the evaluated traits and the reduction of flowering and fruit harvesting times.
