Effects of nano silicon on‏ ‏growth, physiology and biochemical of Dracocephalum ‎moldavica L.‎‏ ‏under salinit stress condiyion

Salinity stress is one of the most important constraint for yield of medicinal plants. In order to investigation the effects of silicon nanoparticle foliar spraying on growth characteristic, physiological and biochemical parameters of dragonhead (Dracocephalum moldavica L.) under salinity stress condition a factorial experiments based on completely randomized design with three repetitions and each repetition, including two pots in hydroponic conditions was carried out at research greenhouse of Mohaghegh Ardabili University at 2018-2019. Experimental factors consisting salinity stress at four levels (0, 50, 100 and 150 mM of Nacl) and foliar spraying of silicon nanoparticle at three levels (0, 100 and 500 mg/l). Morphological studied traits including plant height, fresh and dry weight of plant, physiological parameters such as chlorophyll, electrolyte leakage, relative water contents and biochemical parameters such as proline and antioxidant enzyme activity were measured. Results indicated that salinity stress significantly decreased morphological traits include plant height, fresh and dry weight of plant and physiological parameters such chlorophyll and relative water content of leaves were reduced, while free proline content of leaves and electrolyte leakage from cell membranes were increased. Foliar spraying of silicon nanoparticle alleviated salinity stress effects on dragonhead plants via increases in growth characteristics and enhancing antioxidant enzyme activity such as ascorbate peroxidase and super oxide desmutase. Five hundreds mg/mL of nanosilicon showed the maximum effect on diminishing negative effects of salt stress on most of the parameters. Therefore, the use of nano-form of silicon element is proposed as alleviator of salt stress in dragonhead.