[Effects of Polyethylene Microplastics on the Growth and Quality of Brassica campestris L. in a Three-season Consecutive Cultivation].

Abstract

In order to investigate the effects of polystyrene （PS） microplastics with different particle sizes on the growth, development, and quality of Brassica campestris L. （Chinese cabbage） in consecutive seasons, we studied the effects of PS plastics with different particle sizes （<25, 25-48, 48-150, and 150-850 μm） on the growth and development of B. campestris L. and on the supply of nutrients to the soil in a potting experiment in three consecutive seasons. The results showed that PS microplastics had a significant inhibitory effect on the growth of Chinese cabbage in three consecutive seasons, and the fresh weight, chlorophyll b, and total chlorophyll content of Chinese cabbage were reduced by 9.22%-30.4%, 51.5%-88.9%, and 25.3%-67.1%, respectively. PS microplastics also affected the quality of Chinese cabbage in three seasons and significantly reduced cabbage starch （20.6%-73.2%）, Mn （23.9%-56.3%）, Zn （18.8%-23.2%）, and Cu （18.9%-35.1%） and increased its soluble sugar content （18.9%-220%）. Soil quick-acting phosphorus and quick-acting potassium content under the influence of PS microplastics showed the largest decreases of 26.0% and 55.8%, respectively, but had no significant effect on the effective Cu, Fe, Zn, and Mn contents. Overall, the effect of PS microplastics on the growth and quality of Chinese cabbage increased with the decrease in particle size and decreased with the increase in consecutive planting seasons； however, there was no obvious pattern of change in the effect of PS microplastic particle size on the soil fast-acting nutrient content.