Lead (Pb) is the most common heavy metal contaminant in the environment. To investigate the alleviation of lead stress-induced inhibition of seed germination in wheat, wheat seeds (Triticum aestivum L.) of “Linfeng 3” were pre-soaked with 106 and 107 CFU/mL Bacillus subtilis QM3 for 12 h just before germination under hydroponic conditions and stressed with lead acetate, Pb(CH3COO)2, at five concentrations (50, 250, 500, 1000, 2000 mg/L). The changes of germination rate (GR), germination energy (GE), germination index (GI), vitality index (VI), root length (RL) and shoot length (SL) of wheat seeds had been studied. The results indicated that Pb is accumulated in a dose-dependent manner in wheat, which could exert harmfulness in the early development stage of wheat at inappropriate concentrations. The GR and GE of wheat seeds were reduced 35.0-80.3% and 1.50-58.56% respectively and GI and VI first increased to 103.96% and 120.83% respectively, and then reduced 21.68-58.79% and 8.68-86.52% respectively in wheat seeds after treatments with Pb from the second day till the end of the experiment. The RL and SL also first increased to 105.07% and 108.94% respectively, and then decreased to 2.25-54.79% and 10.35-63.88% respectively with Pb treatment. However, the B. subtilis QM3 influenced the variables evaluated. The GR and GE were found to be increased slightly (p<0.05), GI and VI were also found to be increased remarkably (p<0.05) in wheat seedlings by soaking with B. subtilis QM3 under Pb stress within 7 days after treatments compared with control. Pre-soaked with B. subtilis QM3 also could promote the growth of roots and shoots of wheat seeds under Pb stress. It was concluded that B. subtilis QM3 treatment on wheat seeds may be a good option to improve seed germination and crop establishment under leaded conditions.
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