Effect of light and temperature on seed germination of important me- dicinal and aromatic plants in north western Himalayas

Experiments were conducted during January 2009 at CSIR-Institute of Himalayan Bioresource Technology, Palampur, (HP) India to study the effect of light and temperature on seed germination of important medicinal and aromatic plants viz., Stevia rebaudiana, Salvia sclarea and Tagetes minuta in sand and filter paper. The treatments comprised of two factors viz., light and temperature regimes under room temperature, 20° C and 10° C. Maximum seed germination was observed in the seed which were placed for 2 days open in room temperature and then placed at 20° C in continuous light in all the three plant species in both media except salvia seeds which recorded maximum germination (76%) when placed in room temperature under light condition in sand. S. rebaudiana recorded 58.7 % and 54.7% germination in sand and paper media, whereas, T. minuta recorded 45.3% and 22.7% germination in both medias, respectively when placed in room temperature for 2 days and then incubated at 20° C in continuous light. Among three plant species, maximum seed germination was recorded by the seeds of S. sclarea in paper (89.3%). Seeds placed in sand medium recorded higher germination percentage than the seeds placed on paper in case of Stevia and Tagetes, whereas, in Salvia the trend was reverse. Light is not required for the seed germination of tagetes.