3. Results and discussion
3.1. Essential oil content
Fig. 1 demonstrates the EO content of lemon grass cultivated
with or without levels of Pb and with or without AMF R. clarus
inoculation. The EO content ranged from 0.21 to 0.69% with AMF
inoculation. The level of 100 mg Pb kg−1 soil decreased the EO content
significantly (Fig. 1). Significant changes were not observed
in the EO content in plants without AMF inoculation, the values
being approximately 0.5% independent of the Pb levels in the soil.
Andrade et al. (2009) found that the EO content of lemon grass
ranged from 1.1 to 1.3%, more than double what was found in the
present study.
In a previous study, Lermen et al. (2015) concluded that AMF
inoculation increased plant growth, reduced the accumulation of
Pb in roots and increased the P and N content in plant shoots, but
under high Pb levels, AMF inoculation increased the Pb in shoots.
This might influence EO content and composition. In the preset
study, no significant differences were found for EO content among
treatments with or without AMF inoculation and subjected to 0
and 50 mg Pb kg−1 soil. However, the level of 100 mg Pb kg−1 soil
with AMF inoculation reduced EO content (0.21%), whereas, levels
of 500 and 1000 mg Pb kg−1 soil with AMF inoculation increased
EO content to 0.69% (Fig. 1). Probably, the lemon grass used its secondary
metabolism as a defense against the high concentrations of