Pot marigold (Calendula officinalis L.) as an important medicinal plant is used to treat skin illnesses. As biostimulators containing amino acids can directly or indirectly influence the physiological activities of the plants, this study was done to effects evaluation of bio-stimulators on seed germination and early growth stages of pot marigold. A factorial experiment was conducted on the basis of randomized complete design with three replicates at Institute of Medicinal Plants, ACECR. Bio-stimulators in four commercial formulations of Aminolforte, Kadostim, Fosnutren and Humiforte, and also their concentrations in six levels (0, 0.2, 0.4, 0.6, 0.8, and 1%) were the two studied factors. The studied parameters were: germination percent, germination rate, length of radical and hypocotyl, hypocotyl/radicle length ratio, fresh and dry weight of radicle, hypocotyl and seedling and also content of nutrient elements in seedlings including N, P and K. The results showed that bio-stimulators had significant effect (P<0.01) on all parameters. Of course, the concentration of bio-stimulators hadn’t significant effect on hypocotyl length, fresh weight of radical, hypocotyls and seedling, radical dry weight and germination percent. The interaction effect had significant effect (P<0.01) on the studied parameters except the germination percent, and fresh and dry weight of radical. Also, content of seedlings nutrient elements including N, P and K increased with application of bio-stimulators. In conclusion, application of bio-stimulators has promoted seedling growth of pot marigold and so it is suggested that these compounds have positive effects on seedling establishment in farms.
