Effect of Different Chloride Concentrations on Yield and Nitrate Content of Carrot (Daucus carota L.)

Effect of Different Chloride Concentrations on Yield and Nitrate Content of Carrot (Daucus carota L.) Azmi M. Abu-Rayyan, Nada M. Bsaiso, Sudgi R. Khader Abstract Field experiment was conducted in Jerash area, 45 Km north of Amman-Jordan, to determine the optimum chloride application rate and harvesting date for attaining the lowest nitrate concentration in carrot plants. Using a Randomized Complete Block Design (RCBD) with four replicates, the treatments of chloride application rate (0, 5, 10, 15, and 20 mg kg-1) were investigated; Calcium chloride was used as a source of chloride ion, the amount from each concentration was applied nine weeks after sowing. At two harvesting dates (11 and 15 weeks after seed sowing), nitrate content in the plant of each treatment was determined. Seeds of carrot cultivar Tarenko were used in the experiment. The results indicated that chloride rate has a significant effect on nitrate nitrogen accumulation in the carrot root parts. Lowest nitrate nitrogen accumulation was achieved when 20 mg kg-1 of chloride rate was applied specially in the first harvest. However, nitrate content in the shoot part of carrot was not affected. Chloride content in carrot plants was slightly increased, but it didn’t reach the toxic level. In the second harvest date, the inner part of carrot root (xylem) accumulated nitrate nitrogen at a rate more than that in the outer part of carrot root (phloem). Total nitrogen percent in the root part increased with increasing the rate of applied chloride. On the other hand, carrot root yield (fresh and dry) was not significantly affected by the concentration of chloride added to the soil. Further studies are recommended to evaluate the interactive effect of higher chloride application rates (greater than 20 mg kg-1) and the specific time of harvest (between 11 and 15 weeks after planting) on the plant growth and nitrate accumulation.