微塑料、镉对小麦种子萌发及生长生理的影响

Effects of microplastics, cadmium and their combination on seed germination and growth physiology of wheat

为探讨微塑料、镉及其复合胁迫对小麦种子萌芽和幼苗生长生理特征的影响,分别设计了7个质量浓度的聚苯乙烯微塑料(Polystyrene Microplastics,PS-MPs)和镉(Cadmium,Cd)处理对小麦种子发芽及幼苗生长的影响,进而研究了PS-MPs与Cd复合胁迫对小麦幼苗生长生理的影响。结果显示,与对照相比,在单一PS-MPs胁迫下,对小麦种子的萌发和幼苗的生长均表现为“低促高抑”的变化趋势;在单一Cd胁迫下,小麦种子的萌发也表现为“低促高抑”的变化趋势,而小麦幼苗的根长和芽长均被抑制。PS-MPs与Cd复合胁迫结果显示,较低质量浓度(100 mg/L和200 mg/L)的PS-MPs与Cd复合胁迫对小麦的芽长、超氧化物歧化酶和过氧化氢酶的活性起促进作用,而对丙二醛的活性起抑制作用;较高质量浓度(500 mg/L)的PS-MPs与Cd复合胁迫对小麦的芽长、过氧化氢酶和丙二醛活性无显著影响(p>0.05);PS-MPs与Cd复合胁迫显著抑制了小麦的根长,显著促进了过氧化物酶的活性(p<0.05)。这些结果表明,PS-MPs与Cd复合胁迫显著抑制了小麦幼苗的根长,而较低质量浓度(100 mg/L和200 mg/L)的PS-MPs可通过提高小麦幼苗抗氧化能力来促进Cd胁迫下小麦幼苗的芽长。

To investigate the impact of microplastics,cadmium,and their combination on the physiological characteristics of wheat seed germination and seedling growth,an indoor hydroponic experiment was designed to evaluate the effects of seven mass concentrations of polystyrene microplastics(PS-MPs)and cadmium(Cd)on wheat seed germination and seedling growth.The results indicated that the germination and seedling growth of wheat seeds followed a trend of initial increase followed by decrease with increasing PS-MPs concentration,as compared to the control group.In the presence of Cd stress,the germination of wheat seeds similarly displayed a pattern of initial increase followed by decrease with rising Cd concentration,accompanied by inhibition of root length and shoot length in wheat seedlings.When subjected to combined stress from PS-MPs and Cd,wheat seedlings exhibited enhanced shoot length,SOD,and CAT activities at lower mass concentrations(100 mg/L and 200 mg/L)of PS-MPs,while MDA was inhibited.At higher mass concentrations(500 mg/L)of PS-MPs,the combined stress of PS-MPs and Cd did not have a significant effect on the shoot length,CAT,and MDA activities of wheat(p>0.05),but it notably inhibited the MDA activity of wheat seedlings(p<0.05).The combined presence of PS-MPs and Cd significantly inhibited the root length of wheat while notably promoting POD activity(p<0.05).Meanwhile,the correlation analysis revealed a significant positive correlation between the shoot length of wheat seedlings and SOD and CAT.These findings indicate that the combined stress of PS-MPs and Cd significantly inhibited the root length of wheat seedlings,while lower mass concentrations of PS-MPs(100 mg/L and 200 mg/L)could promote the shoot length of wheat seedlings under Cd stress by enhancing the antioxidant capacity of wheat seedlings.