Common basil (Ocimum basilicum L.) responses to lead (Pb(NOз)2) stress: Germination, morpho-physiological, and phytochemical

The negative impact of contaminated soil with heavy metals on plant and human health is an important global concern. To evaluate the effect of lead (Pb(NOз)2) stress (0, 25, 75, 100, and 150 µM) on the germination, growth, physiological, and biochemical of sweet basil (Ocimum basilicum L.), a pot experiment based on completely randomized design (CRD) with three replicates was conducted at the Department of Horticultural Science, Shahed University of Tehran, in 2018. The contaminated soil with Pb had a negative impact on germination indices (percentage and rate), growth and morphological parameters (shoot and root length and dry weight), and physiological parameters (LAI, photosynthetic pigments, and number of leaf secretory glands). Pb stress (150 µM) led to a reduction in the average of germination percentage (43.33%), germination rate (62.92%), shoot and root dry weight (60.22 and 77.43%, respectively), LAI (64.68%), total chlorophyll content (73.10%), and number of leaf secretory glands (33.3%) in compared to the control treatment (without Pb), while increased peroxidase activity (62.3%), proline content (70.14%), and the root and shoot Pbcontent (92.10 and 97.6%,respectively). On the Other hand, Pb stress led to a change in the content of essential oil compounds. In general, low levels of Pb (25 µM) appear to increase the predominance of oil compounds. In conclusion, common basil cultivation in the Pb contaminated soil could cause undesirable effects on the germination indices, growth and morphological traits, and physiological attributes but might behave a positive influence under low level (25 µM) on the essential oil composition.