Effects of combined contamination with nanoplastics and copper on seed germination and seedling growth of tomato
In order to explore the effects of microplastics and heavy metals on crops,we investigated the effects of polysty-rene nanoplastics(NPs)with a particle size of 50 nm and also the combinatorial effect of NPs and Cu2+on the seed germi-nation and seedling growth of tomato(Solanum lycopersicum L.).The results showed that low concentrations of NPs promoted the germination rate of tomatoes,while high NPs concentration inhibited it.Further,soluble protein content of seedlings was increased,and soluble sugar content was decreased at low concentration(50 mg·L-1),increased at the medi-um concentration(100 and 250 mg·L-1),and decreased at the high concentration(500 and 1000 mg·L-1)again.Under Cu2+ stress alone,mean germination speed and vigor index decreased.Further,treatments with highest concentration(400 mg·L-1)decreased germination index significantly.Moreover,the reduction of bud length,fresh weight and water content of tomato seedlings were observed following Cu2+ treatment.In addition,the soluble protein content increased significantly and the soluble sugar content decreased significantly under Cu2+ stress.The results of combined pollution of NPs and Cu2+ showed that NPs could further reduce the germination index and root length and fresh weight of tomato under Cu2+ pollution,and enhanced the inhibition of Cu2+ on soluble sugar and the promotion of Cu2+ on soluble protein.Therefore,NPs and Cu2+ showed a synergistic effect.In conclusion,NPs could aggravate the toxic effect of Cu2+on tomato seeds and seedlings.
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