Changes in growth, biochemical, and nutrient uptake characteristics of Salvia officinalis L. in response to different levels of nitrogen

To study the effects of different nitrogen levels (0, 70, 140, and 210 mg l-1) on some growth, biochemical, and nutrient uptake (nitrogen, phosphorus, and potassium) characteristics and essential oil content in sage (Salvia officinalis L.) under hydroponic conditions, a pot experiment was conducted based on a completely randomized design with four replications in the research greenhouse of Ferdowsi University of Mashhad in 2019. The results of means comparison showed that with increasing the nitrogen level, the plant growth characteristics increased, so that the 210 mg l-1 N treatment decreased the stem diameter, number of branches, nodes, and leaves, length of internodes, length and leaf width, fresh and stem dry weight, fresh and aerial parts dry weight, and aerial parts dry weight to root dry weight ratio by 54.19, 72.59, 39.49, 82.52, 51.42, 72.20, 71.46, 95.17, 90.31, 95.82, 92.30, and 83.46%, respectively compared to the no N application. The application of 210 mg l-1 N increased the relative content of leaf water (RWC), proline, and essential oil content by 9.57, 266.6, and 14.87% and decreased the electrolyte leakage and malondialdehyde by 30.45 and 51.51%, respectively compared to the no N application. Also, the lowest N level decreased the K, P, and N content by 32.65, 85.13, and 56.89%, respectively compared to the highest N level. The results of this experiment showed that different N levels could have different effects on the growth and essential oil content of sage. Based on the present research findings, the application of 210 mg l-1 N could be recommended for the sage cultivation due to the improving effects on the studied traits of the plant.