Abstract The ubiquitous presence of nano plastics (NPx) and micro plastics (MPx) in the environment has been demonstrated, and as such, the exposure scenarios, mechanisms of plant response, and ultimate risk must be determined. However, the current literature reports ambiguous outcomes and provides limited mechanistic insight into critical governing processes. Here, we performed a meta-analysis of the most recent literature investigating the effect of MPx/NPx on plant species under laboratory and field conditions so as to evaluate the current state of knowledge. Toxic effects of MPx/NPx exposure in plants varies as a function of plant species and interestingly, generally non-significant responses are reported in staple crops. NPx (<100 nm) more negatively affected plant development parameters (n=341) (n is total number of observations), photosynthetic pigments (n=80), and biochemical indicators (n=91) than did MPx (>100 nm). Surprisingly, NPx exposure yielded negligible effects on germination rate (n=17), although root morphology (n=45) was negatively affected. Alternatively, MPx negatively affected on germination (n= 27) and generally non-significant affect with regard to root morphology (n=64). The effect of MPx/NPx on plant health decreases with increasing exposure time. No specific trends were evident for the production of biochemical enzymes as related to MPx/NPx concentration or size. Future work should include crop full life cycle studies to highlight the accumulation of MPx/NPx in edible tissues and also to investigate potential trophic transfer of MPx/NPx. Furthermore, we provide a framework for additional investigative work to address these and other knowledge gaps and to enable accurate assessment of the fate and risk of these materials to environmental and human health. Environmental significance Accumulation of plastic (MPx and NPx) particles is increasing in environmental compartments, and this might be threatened to agricultural plants. Graphical Abstract
