Effect of salinity stress on some mineral contents and biochemical parameters of Ajowan (Carum copticum L. C.B. Clarke)

In order to investigate the effect of irrigation water salinity on some characteristics of Ajowan (Carum copticum L. C.B. Clarke), a field experiment has been conducted in a completely randomized design with 3 replications in Isfahan, Iran during 2013. The treatments involve different levels of saline water, namely 2.5 (control), 6, 9, and 18 dS.m-1. The determined traits include the yield, biochemical parameters, mineral contents, and seed essential oil content and quality. Results show that increasing salinity decreases biological yield and seed yield. Changes in essential oil components, caused by salinity, have been low, showing no specific trend. The major compound in the seed essential oil of C. capticum is thymol (56.1% to 61.2% of the essential oil). The highest concentration of total protein (root: 3.6 and shoot: 8.2 mg g-1 DW) is assigned to the control treatment, dropping significantly as salinity levels rise. Increasing salinity enhances the amount of proline and reducing sugars so that the highest amount of root proline, equal to 12 mg g-1 FW, and reducing sugars (root: 30.5 and shoot: 62 mg g-1 DW) comes from salinity of 18 dS.m-1. Increasing salinity levels raises the amount of phenolic compounds in the shoot, though this increase has not been considerable. The treatment of 18 dS.m-1 has had the lowest concentration of K+ (root: 5 and shoot: 22 mg g-1 DW) and the highest concentration of Na+ (root: 54 and shoot: 64 mg g-1 DW).It can be concluded that by increasing salinity levels, the amount of resistant osmolytes rises.