The combined use of beneficial soil microorganisms enhanced the growth and efficiently reduced lead content in leaves of lettuce (Lactuca sativa L. )‎ plant under lead stress

الملخص EN

Two pots experiments were conducted, during two successive winter seasons of 2016/2017 and 2017/2018, to test the
role of biofertilizer inoculations (arbuscular mycorrhizal fungi, AMF; Bacillus megaterium, B.

megaterium; and their
mixture) in improving growth and quality of lettuce (Lactuca sativa L.

cv.

Balady) under different levels (0, 100, 200 and
300 ppm) of lead (Pb).

The results illustrated that the growth and quality of lettuce were greatly affected by the escalated
levels of Pb in soil.

Clearly, the increased levels of Pb decreased plant growth parameters, the contents of macronutrient
and micronutrient as well as photosynthetic pigments, but increased the contents of Pb in the different parts of lettuce
plants.

Among the tested biofertilizer inoculations, the combined inoculation (AMF + B.

megaterium) showed superior
effects for increasing plant growth, contents of nutrient and photosynthetic pigments.

AMF and the combined inoculation
treatment exhibited an equal efficiency for reducing the content of Pb in the old and new leaves (edible parts) of lettuce
plants, while B.

megaterium showed the best performance in reducing the content of Pb in lettuce roots.

Our study
suggested that the combined inoculation (AMF + B.

megaterium) is an effective tool for improving growth and quality of
lettuce in high-contaminated soil with Pb.