Effect of Salinity Stress and Planting Method on Morphological and Physiological Characteristics of Licorice in Greenhouse

This study aimed to determine the response of licorice (Glycyrrhiza glabra L.) to different methods of planting and different levels of water salinity. The experiment was conducted as factorial based on a completely randomized design with 3 replications, during 2019-2020 in Salinity Research Center, Yazd, Iran. Treatments included five levels of water salinity ( 0.9 [control], 3, 6, 9 and 12 dS/m), and two planting methods (transplanting and direct seeding). Morphological traits such as plant height, number of lateral branches, leaf area, total dry weight, and physiological traits such as total chlorophyll and carotenoids, and sodium and potassium contents were measured. The results showed that the highest plant height (62 cm) was in the control (0.9 dS/m) and transplanting method, maximum number of lateral branches (70 per plant) and largest leaf area (1032 cm2) were obtained in the control treatment, maximum total dry weight (2.68 g/plant) was in control and transplanting method, and the maximum carotenoids content (5.5 mg/gFW) was in the control and transplanting.  In the control and direct seeding treatment, maximum  total chlorophyll content (51.21 mg/g FW) and the highest amount of potassium (14.8 mg/kg DW) were observed.  The maximum sodium content (15.2 mg/kg DW) was obtained in 12 dS/m and transplanting treatment. In general, with increasing salinity level to 12 dS/m, plant height in both planting methods decreased. Also, with increase in water salinity,  the number of lateral branches and leaf area decreased by 84% and 88.5%, respectively. Total chlorophyll, carotenoids, and potassium also decreased significantly, but the amount of sodium ion increased. Transplanting was less affected by salinity in most parameters, except the total chlorophyll and sodium. Higher salinity stress had negative effect on different licorice plant parameters including plant height, number of lateral branches, leaf area, as well as the amount of total chlorophyll and carotenoids. In general, transplanting was more productive than direct seeding. The findings of this study show that, in situations with scarcity in fresh water, seedlings should be watered with fresh water, and saline water should be used for irrigation after transplanting.