Potential impacts of two types of microplastics on <em>Solanum lycopersicum</em> L. and arbuscular mycorrhizal fungi

Abstract

Microplastics (MPs) in agricultural soils are a major concern. Relatively few studies have been carried out to explore its potential impacts on crops and soil microbiota. The study investigates the effects of two different types of MPs (microfiber, MFB and microfilms, and MFL) on the growth of Solanum lycopersicum L. (tomato) and Arbuscular Mycorrhizal Fungi (AMF). A pot experiment was conducted with MFB and MFL concentrations viz., 0.4, 2.4, 4.4, 6.4, and 8.4% (w/w) and control without MPs (n = 6). Plant height was measured weekly for 13 wk before plants were harvested destructively. Growth increment, relative growth rate (RGR), and root: shoot ratio (RSR) were calculated. Leaf chlorophyll levels were measured. AMF spores were quantified using the wet sieving and decanting method. Plants showed a concentration-dependent decline in growth, regardless of the MP type. RSR demonstrated a decline with increasing MP concentration. Compared to the control, plants declined the allocation of shoot biomass by 40-74% and root by 6-75%. Plants in MFBs reported a higher chlorophyll content than in MFLs (F = 18.33; p ≤ 0.000). MPs significantly reduced AMF spore abundance in soils, indicating adverse effects on the soil microbiota. The study concluded that MPs impose negative effects on both vegetative growth of tomato and AMF spores. Further studies are imperative to explore the link between MPs and, crop growth and AMF.

Keywords

• microfibers, microfilms, vegetative growth, tomato, amf spores