Accumulation characteristics of cadmium in farmland soil by Pueraria thomsonii

The selection of rich plants with high growth, high biomass, and high economic value is a new breakthrough in the bioremediation of heavy metals. To study the accumulation characteristic of cadmium (Cd) by Pueraria thomsonii in farmland soil, field experiments were conducted to investigate Cd contents in tuber (radix pueraria and arrowroot), basal part of stem, main vine, lateral branch, and leaf of Pueraria thomsonii under three pollution levels. The results showed that Cd contents in different parts of Pueraria thomsonii were lateral branch (8.96 mg/kg) > main vine (6.85 mg/kg) > leaf (5.22 mg/kg) > basal part of stem (2.80 mg/kg) > radix pueraria (1.36 mg/kg)> tuber (1.21 mg/kg)> arrowroot (0.16 mg/kg). Cd contents increased with the increase of soil pollution, showing that Cd contents in medium and high pollution were significantly higher than in low pollution (P < 0.05). Except for tuber, the accumulation coefficient of Cd in other parts of the plant was higher than 1 (1.09-8.65), and the transport coefficient was 2.59-8.98. The distribution rates of Cd content in various parts of Pueraria thomsonii were as follows: lateral branch (35.64%-43.81%) > main vine (21.55%-25.49%) > leaf (15.40%-23.63%) > tuber (7.03%-9.94%) > basal part of stem (5.99%-9.57%). The biomass in various parts of Pueraria thomsonii was tuber > lateral branch > leaf > main vine > basal part of stem. The removal amount of Cd increased with the pollution level, which was high pollution (45.39 g/hm²) > medium pollution (39.96 g/hm²) > low pollution (16.56 g/hm²). In general, Cd contents in various parts of Pueraria thomsonii were significantly positively correlated with soil organic matter, available Cd, and total Cd, but negatively correlated with soil pH. In the treatment of Cd contaminated farmland soil, Pueraria thomsonii (used as arrowroot) has application value for Cd contaminated farmland soil remediation.