Difference of Cadmium Bioaccumulation and Transportation in Two Ryegrass Varieties and the Correlation between Plant Cadmium Concentration and Soil Cadmium Chemical Forms

Pot experiments were conducted to study the effects of different cadmium (Cd) levels (0, 75, 150, 300 and 600 mg kg−1) on the growth, cadmium concentration and cadmium accumulation of two varieties of ryegrass, and the correlation between plant cadmium concentration and soil cadmium chemical forms. The results showed that root dry weight of the two varieties of ryegrass, dry weight of shoot and plant in Aubade increased first and then decreased with the increase of soil cadmium. When the soil cadmium level was 75 mg kg−1, shoot dry weight and plant dry weight in Aubade reached the maximum (10.92 g pot−1 and 12.03 g pot−1), which was 11.13% and 10.67% higher than that of the control respectively. The cadmium form in shoot of the two ryegrass varieties was dominated by was sodium chloride extraction (F-NaCl), followed by deionized water extracted (F-W) and acetic acid extracted (F-HAC). The cadmium forms in soils were mainly exchangeable (EXC-Cd), and cadmium concentrations of leaf, stem and root were significantly positively correlated with exchangeable cadmium content in the rhizosphere soil (P < 0.01). The EXC-Cd content in Abbott soil was higher than that in Bond, which was consistent with Abbott’s Cd absorption above Bond. The cadmium transport factor of the two ryegrass varieties were less than 1, and cadmium bioconcentration factor were all greater than 1. In comparison of the two ryegrass varieties, the dry weight of shoot and plant of Abbott were higher than that of Bond under the stress of 75–600 mg kg−1 Cd. The cadmium concentration and cadmium accumulation of shoot and root in Abbott were also higher than that of Bond. There was a genotypic difference in ryegrass tolerance to cadmium and cadmium absorption. Abbott was more suitable as a phytoremediation material for soil cadmium pollution.