In order to evaluation of mitigation effect on salinity stress on the morphological and biochemical properties of ornamental marigold plant (Tagetes erecta L. Nana), an experimental was carried out in factorial arrangement base on randomized complete block design in three replications at Khorasan Razavi Agriculture Research and Education Center in 2018. The first factor was four salinities (0, 4, 8, 12 dS m-1) and the second factor was potassium silicate (PS) at three levels (0, 100 and 150 ppm). The results showed that the highest plant height was obtained at zero salinity with application 100 ppm PS. The highest shoot dry weight was recorded at salinity of 8 dS m-1 with 150 ppm PS. The highest amount of leaf potassium was observed at salinity of 12 dS m-1 with using of 100 ppm PS and the highest amount of root potassium was obtained at 4 dS m-1 salinity treatment with 100 ppm PS. The results was also showed that in marigold plant at high salinity (more than 8 dS m-1), potassium silicate composition could not have a favorable effect on plant growth. The use of PS in salinity of 12 dS m-1 was able to reduce the concentration of sodium in leaf tissues and increase the amount of potassium, although the amount of potassium increase was higher in low salinities. In general, the use of potassium silicate can be considered as a supplement in plant nutrition at low salinities. Manuscript profile