Decreasing Plant Abiotic Stress in the Soil Treated with Sewage Sludge Using Piriformospora indica Fungus and Multi Walled Carbon Nanotubes

Abstract

Today, finding suitable methods to decrease plant abiotic stress such as heavy metals or salinity is very necessary in arid and semi-arid regions. Thus, this research was conducted as a factorial experiment in the layout of a completely randomized block design to evaluate the role of Piriformospora indica fungus and multi-walled carbon nanotubes (MWCNTs) on decreasing plant abiotic stress in the soil treated with lead (Pb)-polluted sewage sludge. The treatment consisted of applying sewage sludge at the rates of 0, 15, and 30 t/ha, 3 levels of cadmium spiked in to the applied sewage sludge (0, 800 and 1600 mg Pb/kg), as well as 0%, 0.5%, and 1.5% (W/W) MWCNTs in the presence and absence of P. indica. The plant used in this experiment was barely. After 90 days of the experiment, the plant was harvested and its Pb concentration was measured using atomic absorption spectroscopy. Applying 0.5 and 1% (W/W) MWCNTs in the soil treated with 15 t/ha sewage sludge significantly decreased plant Pb concentration by 8.1% and 12.3%, respectively. In addition, the presence of P. indica had significant effects on decreasing plant Pb concentration since the lowest plant Pb concentration was observed in soil amended with 30 t/ha sewage sludge (800 mg Pb/kg) by receiving 1.5% (W/W) MWCNTs in the presence of P. indica. The results of this study showed that applying MWCNTs has significant effects on decreasing soil heavy metals or soil salinity that is a positive point in environmental studies.

Keywords: Multi walled carbon nanotubes, Sewage sludge, Pb, Microbial respiration,