@article{LI2026, 
author = {Min LI and Ying CHEN and Hailong LIU and Yiqun XU and Dongying LI and Xiaozhi WANG},
title = {Design for the experimental teaching of the toxicity of novel pollutants in crops: Microplastics as an example},
year = {2026},
journal = {Experimental Technology and Management},
volume = {43},
number = {7},
pages = {283-291},
keywords = {polystyrene microplastics, UV aging, seed germination, photosynthesis, oxidative stress},
url = {https://www.sciopen.com/article/10.16791/j.cnki.sjg.2026.07.033},
doi = {10.16791/j.cnki.sjg.2026.07.033},
abstract = {ObjectiveTo improve the scientific thinking, innovation awareness, and practical ability of undergraduate students majoring in environmental science and engineering, an innovative experimental course was launched. The toxicity assessment of novel pollutants is one of its key points.MethodsIn this study, polystyrene microplastics (PS MPs), which are ubiquitous in daily life and new pollutants, were chosen as the research object. Rice (Oryza sativa L.) is a crop widely cultivated across the country, and was the test material. An experiment on the toxicity effects of original and aged PS MPs on rice seed germination and seedling growth was designed. Seed germination rate, germination potential, and germination index served as critical indicators of seed germination. The effects of PS MPs on seedling growth were characterized by phenotypic (i.e., biomass, plant height, and root length) and physiological biochemical indicators (i.e., chlorophyll contents, photosynthetic parameters, and antioxidant enzyme activities). By comparing variations in crop toxicity between the original and aged PS MPs at the same concentration, the influence of aging on such adverse effects is clarified.ResultsThe original as well as the aged PS MPs at 100, 200, and 500 mg L−1 inhibited the three seed growth indicators. The germination rate declined significantly from 76.3% in the control to 31.7%, 26.7%, and 20.0% in the 500 mg L−1 original and 200 and 500 mg L−1 aged PS MP treatments, respectively (p < 0.05). Further, the degree of inhibition showed a dose–effect relationship. However, at the same concentration, the effects of the original and aged PS MPs on the above indicators (p > 0.05) did not differ significantly. The plant height declined from 30.3 cm in the control to 27.1 cm and 27.7 cm in the 50 and 100 mg L−1 aged PS MP treatments, respectively (p < 0.05). Compared to the control, the original PS MPs at 100 mg L−1 and the aged PS MPs at 50 and 100 mg L−1 markedly reduced the chlorophyll content of rice leaves (p < 0.05). Upon exposure to 100 mg L−1 aged PS MPs, the intercellular CO2 concentration, the net photosynthetic, and transpiration rates of rice leaves reduced by 45.2%, 58.1%, and 58.1% (p < 0.05); however, at the same concentration, the original PS MPs did not significantly affect these indicators (p > 0.05). The trends in oxidative stress-related indicators suggested that 100 mg L−1 original and 50 and 100 mg L−1 aged PS MPs induced oxidative stress in rice roots, which partially explained the inhibition of photosynthesis in rice seedlings by PS MPs. Compared with the original PS MPs, the aged ones were more potent in inhibiting height and photosynthesis in rice seedlings and inducing oxidative stress.ConclusionsThese results provide useful information for understanding the toxicity of aged MPs on crops and for a comprehensive assessment of the long-term ecological risks of MPs. This innovative experiment integrates theoretical knowledge and experimental skills for environmental toxicology, biology, and analytical chemistry in two stages of rice seed germination and seedling growth, and intuitively clarifies the toxicity of aged PS MPs against crops via multiple indicators. It not only deepens the students’ knowledge and comprehension of the toxicity of novel environmental pollutants, but also promotes their integration and flexible application of the learning, further strengthening their practical innovative ability.}
}