Effects of molybdenum and polystyrene microplastics on growth and antioxidant capacity of alfalfa seedlings

ZHU Ruo-lin; ZHU Wen-yan; YANG Yi-xin; WANG Bei-bei; SUN Ping

doi:10.13557/j.cnki.issn1002-2813.2024.20.019

Abstract：The experiment aimed to investigate the effects of single and combined stress of heavy metal molybdenum(Mo)and polystyrene microplastics(PS-MPs)on the growth and antioxidant capacity of alfalfa seedlings.Alfalfa was used as the research subject,and the effects of different concentrations of Mo(0,0.1,1.0,10.0,50.0,100.0 mg/L)and PS-MPs(0,5,10,20,50,100 mg/L)on the growth and antioxidant indicators of alfalfa seedlings were detected.The results showed that under single Mo stress,low concentrations of Mo(0.1,1.0 mg/L)promoted the synthesis of chlorophyll,and the content of chlorophyll A,chlorophyll B,and total chlorophyll increased.High concentrations of Mo(50 mg/L)inhibited the growth indicators,chlorophyll content,and antioxidant enzyme activity of alfalfa,and increased the content of malondialdehyde(MDA).Under single PS-MPs stress,the growth indicators and chlorophyll content of alfalfa seedlings in the PS20 group were lower than those in the PS0 group,and the MDA content was higher than other groups.The antioxidant enzyme activity in the PS100 group was inhibited.Under combined stress,the activities of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD),and the content MDA in the Mo-PS5 group of alfalfa were significantly lower than that in the Mo-PS0 group.Compared with the Mo-PS0 group,the growth indicators of alfalfa in the Mo-PS20 group were all reduced,and the MDA content was the highest,and the antioxidant enzyme activity in the Mo-PS100 group was significantly reduced(P＜0.05).The study showed that both single stress of Mo and PS-MPs,as well as their combined stress,could inhibit the growth of alfalfa seedlings.Under combined stress,low concentrations of PS-MPs could alleviate the oxidative damage caused by Mo stress,while high concentrations of PS-MPs would exacerbate the growth inhibition and oxidative damage caused by Mo stress.