Growth And Accumulation Characteristics Of Xanthium Strumarium And Xanthium Sibiricum Under Cadmium Stress

Invasive plant has become a major concern in today's society.Cadmium is one of the main heavy metal elements currently causing soil pollution.To investigate whether invasive plants can invade areas contaminated with heavy metal cadmium,we use Xanthium strumarium and Xanthium sibiricum as research material,through seed germination and seedling growth experiments(0,10,40,80,120 mg·L^-1)and potted simulation experiments(0,2.5,5,10,40,80,120 mg·kg¹)to judge the tolerance and enrichment of the invasive plant X.strumarium to heavy metal cadmium,and further enrich the invasion mechanism of X.strumarium.The results of seed germination and seedling growth test showed that cadmium promoted the germination of X.strumarium and X.sibiricum seeds.The germination rate,germination potential and germination index of X.strumarium were significantly higher than that of X.sibiricum;The length and root length of X.strumarium were significantly higher than X.sibiricum;The chlorophyll content of X.strumarium seeding was higher than X.sibiricum at high concentration?80 and 120 mg/kg?,but the cotyledon guaiacol peroxidase activity was not higher than X.sibiricum.The above results indicated that the tolerance of X.strumarium seeds to heavy metal cadmium was higher than X.sibiricum under cadmium stress.On the one hand,this may be due to the action of other antioxidant enzymes in the antioxidant enzyme system;On the other hand,the seeds of X.strumarium are larger than X.sibiricum and can store more nutrients.In this experiment,the base liquid is distilled water,which eliminates the influence of different ions on the growth and development of the plant.The growth and development of the plant depends on the plant itself,it may enhanced its resistance to heavy metal cadmium.The results of pot experiment showed that the roots,stems,leaves and total dry weight of X.strumarium were significantly higher than X.sibiricum at seedling stage and flowering stage.The biomass characteristics of the two growth stages showed the same trend.High biomass can enhance the tolerance of plants;At the seedling stage and flowering stage,the specific leaf area of ?? X.strumarium was increased with the increase of cadmium stress,and X.sibiricum was decreasing.The high specific leaf area can help plants receive more light energy and improve the light and utilization efficiency of plants.At the seedling stage,the photosynthetic pigment content of X.strumarium was significantly higher than X.sibiricum under high concentration of cadmium stress(40,80,120 mg·kg¹).However,at the flowering stage,the chlorophyll content of X.strumarium was significantly lower than X.sibiricum at all concentrations.On the one hand,it may be due to the early flowering of X.sibiricum from the seedling to the flowering stage,and X.sibiricum lasted 66 days.X.strumarium is 88 days,so the leaves of X.sibiricum are poisoned by heavy metal cadmium for a short time,and the chlorophyll content is stillmaintained at a high level.Another reason is that the cadmium content in the leaves of X.sibiricum is very low,and the degree of toxicity is lower than X.strumarium.The Translocation Factor of X.strumarium and X.sibiricum were less than 1,and they were not hyperaccumulators of heavy metal Cadmium.Under the condition of high concentration of cadmium?80,120 mg/kg?,the transfer ability of X.strumarium to heavy metals was higher than X.sibiricum.In summary,the tolerance and transfer ability of X.strumarium to heavy metal cadmium is higher than X.sibiricum,which may invade areas contaminated with heavy metal cadmium.