Effect of light quality on seed germination and seedling growth of six medicinal plant species in Tarai region, Uttarakhand

The influence of light quality (direct light, red, far-red and dark) on seed germination and seedling growth was examined in six different medicinal plant species viz., Lepidium sativum Linn., Spilanthes acmella Linn., Matricaria chamomilla Linn., Ammi majus Linn., Andrographis paniculata Nees. and Cassia tora Linn. in Tarai region of Uttarakhand with three replicates for 15 days under laboratory conditions. The results revealed that the rate of germination and per cent seed germination differ from species to species and light conditions. The per cent seed germination was maximum inL. sativum (89.67% in far - red) and minimum in M. chamomilla (40.0% in direct). M. chamomilla and S. acmella was failed to germinate under dark condition, whereas L. sativum showed maximum per cent seed germination (62%). The seedling growth in terms of length (cm) and dry weight (mg) of 15 days old was significantly affected by light quality in all the species. All the species exhibited maximum radicle length (cm) under direct light except in S. acmella (6.67 in red light) whereas plumule length (cm) was maximum in C. tora (11.78), L. sativum (8.59), A. paniculata (7.18) and A. majus (5.93) in dark. Interestingly, maximum total seedling dry weight (mg) was under direct light in all the species and it was maximum in C. tora (7.06) and minimum in M. chamomilla (2.80) indicating that direct light is favourable for seedling growth.