Physiological and Biochemical Characteristics of 4 Farmland Weeds Under Zn and Cd Stress and Accumulation Characteristics of Heavy Metals

Four kinds of farmland weeds were used as test materials, and hydroponic experiments were carried out to analyze the physiological and biochemical properties and heavy metal enrichment of 4 kinds of farmland weeds under different stress conditions of zinc and cadmium. The subordinate function method was adopted to improve the plant resistance to carrying capacity comprehensive evaluation. The results showed as follow under the single stress of Zn and Cd, with the increasing of the concentration of Zn and Cd, the contents of free proline and malondialdehyde of the 4 plants increased, while the activities of chlorophyll, soluble sugar, soluble protein and peroxidase increased first and then decreased. Under the single stress of Zn and Cd, the accumulation of Zn and Cd in the aboveground parts and roots of 4 kinds of farmland weeds increased with the increasing of the concentration of Zn and Cd. At the same treatment level, the accumulations of Zn and Cd of 4 plants were Silence conoidea > Cirsium setosum > Buglossoides arvensis > Descurainia sophia. The evaluation of subordinate function showed that the order of the pollution resistance of 4 plants under Zn stress from strong to weak was B. arvensis > S. conoidea > C. setosum > D. sophia. Under the Cd stress, the pollution resistance of 4 plants was as follows: B. arvensis > C. setosum > S. conoidea > D. sophia. On the whole, all 4 kinds of farmland weeds have certain tolerance and resistance to heavy metal stress, while B. arvensis has the strongest anti-pollution ability to Zn and Cd, and D. sophia has the weakest.