Arbuscular mycorrhizal fungi and pistachio husk biochar combination reduces Ni distribution in mungbean plant and improves plant antioxidants and soil enzymes.

Soil pollution with nickel (Ni) casts detrimental effects on the quality of crops. Low-cost amendments can restrict Ni mobility in soil and its uptake by the plants. In this pot experiment, the effects of pistachio husk biochar (PHB) and arbuscular mycorrhizal fungi (AMF) on the distribution of Ni in mung bean and its bioavailability in Ni-spiked soil were evaluated. Plant parameters like Ni plant height, root dry weight, shoot dry weight, grain yield, chlorophyll contents, oxidative stress, Ni distribution in the roots, shoot, and grain, as well as the nutritional potential of grains, were measured on plants grown on Ni-contaminated soil amended or not (control) with AMF, zeolite (ZE), PHB, ZE + AMF, and PHB + AMF. Moreover, DTPA (diethylenetriamine pentaacetate)-extractable Ni in the soil, microbial biomass carbon (MBC), total glomalin (TG), extractable glomalin (EG), mycorrhizal root colonization (MRC), and the activities of soil enzymes (i.e. urease, acid phosphatase, and catalase) were also assessed after the plant harvest. With few exceptions, all treatments had significant effects on plant and soil parameters. The PHB + AMF treatment showed the topmost significant increment in plant physical parameters while reducing the Ni distribution in plant parts and oxidative injury. Based on these findings, it is proposed that PHB + AMF treatment can reduce Ni distribution and oxidative stress in mung bean plants and improve the biochemical compounds in grain.