Effects of cadmium and lead on seed germination, morphological traits, and essential oil composition of sweet basil (Ocimum basilicum L.)

Abstract

The negative impact of contaminated soil with heavy metals on plant and human health is an important global concern. The aim of this study was to explore the influence of cadmium (Cd) and lead (Pb) on seed germination, morphological traits, and essential oil (EO) composition of sweet basil (Ocimum basilicum L.). Two months prior to the experiment, soils pre-treated using Cd (0, 5, 10, 20) and Pb (0, 100, 200, 400) in mg kg soil−1. Seeds were sown in the pots containing the contaminated soil under greenhouse conditions at 26 ± 6 °C and 60–70 %RH. The amount and composition of EO were determined using Gas chromatography–mass spectrometry (GC-MS). The contaminated soil had a negative impact on seed germination, leaf area, and flowering, stem growth and plant dry mass. The extracted EO yield was varied (P > 0.05) among the applied treatments from 0.28 to 0.39% (v/w). The GC-MS analysis of the EO identified the presence of 38 compounds. The major identified components of the EO were included estragole (18.80–50.32%), 2, 6- octadienal (3.2–11.95%), caryophyllene oxide (0.98–10.69%), caryophyllene (0.42–5.70%), phthalic acid (1.43–47.89%), and geranial (2.60–9.43%). The canonical correspondence analysis (CCA) showed a positive correlation between the plant height and phthalic acid contents. In conclusion, sweet basil cultivation in the Cd and Pb contaminated soils could cause undesirable effects on the seed germination and morphological traits, but might be have a positive influence on the EO yield, composition and phytoremediation of the soil.