Plastic debris can break down into smaller particles due to different environmental factors, and become micro-nanoplastics (MNPs). Foliar accumulation of MNPs in leafy crops could negatively affect plant productivity and nutritional value and therefore poses a direct threat to plants.

A group of researchers from Xishuangbanna Tropical Botanical Garden (XTBG) recently investigated the accumulation of polystyrene nanoplastics (PS-NPs) in leafy vegetable leaves and its ecological consequences. They also explored the impact of PS-NPs on plant leaf cuticles and trichomes, and analyzed the potential ecological effects.

Results of their study were published in Journal of Hazardous Materials.

The researchers examined the foliar uptake of PS-NPs in four common leafy vegetable species: Brassica rapa var. chinensis, Amaranthus viridis, Brassica rapa var. parachinensis, and Allium tuberosum and exposed them to different concentrations of PS-NPs under controlled experimental conditions.

Through microscopy observation, the researchers found that PS-NPs can accumulate in the leaves of leafy vegetables, with accumulation varying by species, leaf side and their interactions. Plants with smooth surfaces and lacking trichrome andepicuticular wax exhibited higher capacity to accumulate particles compared to plants with trichomes.

Smaller particles had a great ability to penetrate the cuticle and epidermis cells of leaves, the study found. Foliar exposure to PS-NPs resulted in physiological effect and growth reduction of leafy vegetables.

Exposure to PS-NPs via foliar spray has significant impact on the chlorophyll content and photosynthesis rate of leafy vegetables, subsequently affecting their growth, nutrition, and overall fitness, according to the study.

"We should take the accumulation of PS-NPs and potential ecological risks seriously, especially in agricultural production and environmental protection,” said XU Guorui, one of the corresponding authors of the study and a researcher from XTBG.

The study provides important insights into the potential risks posed by MNPs to plant health and food security, said XU.

XU Guorui Ph.D

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China

E-mail: xuguorui@xtbg.ac.cn  

Published: 29 October 2024