Abstract：
Photosynthesis provides carbon sources and energy for crop growth and development, and the widespread presence of microplastics and plastic plasticisers in agricultural soils affects crop photosynthesis, but the mechanism of the effect is not clear. This study aims to investigate the effects of different microplastics and plasticizers on cucumber photosynthesis. Using polyvinyl chloride (PVC), polyethylene (PE), polystyrene (PS), and di-n-octyl phthalate (DOP) as representative microplastics and plasticizers, we assessed their impact on cucumber photosynthesis. Our results reveal significant alterations in key parameters: intercellular CO2 concentration (Ci) and transpiration rate (Tr) increased across all treatments, whereas stomatal limit value (Ls) and water use efficiency (WUE) decreased. Notably, PS + DOP treatment led to a significant reduction in the maximum efficiency of photosystem II (Fv/Fm) and ATP accumulation. Furthermore, PE and PS + DOP treatments decreased lycopene and ɛ-carotene synthesis rates, as well as abscisic acid (ABA) accumulation. All treatments inhibited the conversion of β-carotene into strigolactone (SL) and decreased chlorophyll synthesis rates, with PS + DOP exhibiting the most severe impact. Regarding chlorophyll degradation pathways, PVC and PE treatments reduced chlorophyll decomposition rates, whereas DOP with PS promoted degradation. PE and PS treatments also impaired light energy capture, electron transport, and the structural stability of photosystems I and II, as well as photosynthetic capacity and NADPH and ATP synthesis rates. Our findings underscore the differential impacts of microplastics and plasticizers on cucumber photosynthesis, with PS + DOP having the most detrimental effect. These results shed light on the complex interactions between microplastics and plant physiology, highlighting the urgent need for mitigation strategies in agricultural practices to safeguard crop productivity and environmental sustainability.
摘要：
光合作用为作物生长发育提供碳源和能源,农业土壤中广泛存在的微塑料和塑料增塑剂会影响作物的光合作用，但其作用机制尚不清楚。本研究旨在研究不同微塑料和增塑剂对黄瓜光合作用的影响。使用聚氯乙烯（PVC），聚乙烯(PE),聚苯乙烯（PS），和邻苯二甲酸二正辛酯（DOP）作为代表性的微塑料和增塑剂，我们评估了它们对黄瓜光合作用的影响。我们的结果揭示了关键参数的显着变化：细胞间CO2浓度（Ci）和蒸腾速率（Tr）在所有处理中增加，气孔极限值（Ls）和水分利用效率（WUE）下降。值得注意的是,PSDOP处理导致光系统II的最大效率（Fv/Fm）和ATP积累显着降低。此外，PE和PS+DOP处理降低了番茄红素和胡萝卜素的合成率，以及脱落酸（ABA）的积累。所有处理均抑制了β-胡萝卜素转化为分离金内酯(SL)并降低了叶绿素合成速率,PS+DOP表现出最严重的影响。关于叶绿素降解途径，PVC和PE处理降低叶绿素分解率，而DOP与PS促进降解。PE和PS治疗也损害了光能捕获，电子传输,以及光系统I和II的结构稳定性，以及光合能力和NADPH和ATP合成速率。我们的发现强调了微塑料和增塑剂对黄瓜光合作用的不同影响，其中PS+DOP具有最有害的影响。这些结果揭示了微塑料和植物生理学之间的复杂相互作用，强调迫切需要在农业实践中采取缓解战略，以保障作物生产力和环境可持续性。
