Effect of electrical conductivity (EC) of nutrient solution on quantitative and qualitative traits of three ecotypes of licorice (Glycyrrhiza glabvra L.) in hydroponic culture

Licorice (Glycyrrhiza glabra L.) is a perennial medicinal plant which its root and rhizome extract broadly use for food and pharmaceutical industries. Considering the necessity of its domestication as an alternative approach for its wild collection, this experiment was counducted to investigate the effect of electrical conductivity (EC) of nutrient solution on growth and yield of three licorice ecotypes under hydroponic culture.

the experiment was conducted as factorial based on randomized complete block design with three replications in Research Greenhouse of Department of Horticultural Science and Landscape Engineering, University of Tehran in 2018. Treatments were included four levels of electrical conductivity (EC) of nutrient solution (1.5, 2, 2.5 and 3 dS.m-1) and three licorice ecotypes (Baft and Lalehzar from Kerman province and Eqlid from Fars province). In this study, some morphophysiological traits such as plant height and diameter, main stem diameter, number of lateral branches per plant, internode length, leaf area, root length and diameter, root and shoot fresh and dry weight and some biochemical traits such as Chlorophyll index, total phenol content and total antioxidant activity were measured.

the results showed that there was a significant difference between ecotypes on all studied traits except total phenol and total antioxidant activity. Also, different levels of electrical conductivity significantly affected the studied traits, except for root dry weight and total phenol. The interaction effect of both treatments was significant in terms of the morphophysiological and biochemical traits. In each of the three ecotypes studied, with increasing the electrical conductivity of the nutrient solution, plant height and diameter, internode length, leaf area and root diameter showed a decreasing trend. The highest dry weight of shoots was observed in Baft ecotype from Kerman with electrical conductivity levels of 1.5 and 2 dS.m-1 (4.51 and 4.91 g.plant-1, respectively) and Eghlid ecotype from Fars with electrical conductivity of 2.5 dS.m-1 (4.91 g.plant-1). Also, Baft ecotype from Kerman showed the highest dry weight of root (16.02 g.plant-1) in electrical conductivity of 3 dS.m-1. In terms of biochemical traits, the highest amount of chlorophyll index was observed in Lalehzar ecotype from Kerman and electrical conductivity level of 2.5 dS.m-1. The highest amount of total phenol and percentage of antioxidant activity was related to Lalehzar ecotype at the electrical conductivity level of 3 dS.m-1.

according to the results, Baft ecotype from Kerman province and then Eqlid from Fars province in range of electrical conductivity level of 1.5-2 dS.m-1 performed better while in terms of quality criteria, Lalehzar ecotype from Kerman showed the highest amount in electrical conductivity of 3 dS.m-1 compared to other treatments.