## 4 Discussion
### Sinapis Alba L. Response to LDPE Microplastic: Pot Experiment  
In the pot experiment, seed germination of _S. alba_ was evaluated across three treatment groups: Control (0% LDPE) and two concentrations of LDPE MP (1% and 5%). After ten days, germination percentage was highest in the 1% LDPE treatment, followed by the Control and 5% LDPE. The GSI, reflecting daily germination dynamics over 10 days, showed slightly higher values in the control than in 1% and 5% LDPE treatments, indicating a minor delay in germination speed with LDPE presence. In both experiments, treatments with different MP concentrations resulted in a similar total germination percentage and GSI, indicating that the MP particles themselves probably have little or no effect on germination. A study on germination of _L. multiform_ exposed to MP particles and leachates showed similar results for germination [58]. The same statistical results were shown for two tomato varieties whose seeds were exposed to PP-MP, although the germination rate of both varieties was slightly higher compared to the Control, indicating a possible influence of PP-MP on alpha-amylase activity, which leads to the degradation of starch readily available for germination [40]. The slightly greater sprout length observed in both LDPE treatments, particularly the high variability in the 5% LDPE treatment, suggests that microplastics may influence early plant development in a non-uniform manner. While ANOVA indicated an overall significant difference among treatments, the marginal effect revealed by [PERSON]'s test and the lack of clear significance between 1% LDPE and the Control or between 1% and 5% LDPE imply that the observed trends should be interpreted with caution. These results may reflect species-specific resilience of _S. alba_ to LDPE particles at the tested concentrations, or they may be influenced by indirect factors such as altered substrate aeration or water retention caused by the presence of MPs [14; 33]. The non-significant result of the effect of MPs on shoot growth [40] was probably attributed to the insufficient exposure time of the plants to MPs, which could also be the reason for the non-significance of the differences in our study. In their work, Ref. [5] demonstrated that _Lepidium sativum_ exposed to high concentrations of polyethylene MPs exhibited reduced shoot length within the first 24-48 h of exposure. However, these effects were often transient and diminished after the initial period [5]. Over longer exposure periods (>7 days), plant responses to MPs can vary further. In some cases, plants recover, and sprout length differences become negligible, whereas in others cumulative negative effects emerge [14; 40]. On the other hand, the literature reports [59] that the positive effect of MPs on plant biomass may be attributed to improved soil aeration, which can enhance root penetration and nutrient uptake, as well as the potential role of microplastics as a carbon source that stimulates soil microbial activity. The relationship between MPs and plant development is further complicated by their interactions with soil properties. MPs can significantly alter physical and chemical properties of soil, thereby affecting factors such as water retention and nutrient availability--both of which are critical for seedling establishment and growth [11; 60]. For instance, MPs can modify soil structure, resulting in changes to pore connectivity and shifts in microbial activity, which can either alleviate or intensify stress conditions experienced by plants [9; 61]. Additionally, further literature [59] suggests that future research should encompass a wider range of plastic morphologies (e.g., fibers, foams, fragments) and polymer types (e.g., polystyrene, polyvinyl chloride) based on the vital impact of plastic particles on plant-soil systems. Investigating these variables across a spectrum of concentrations would better represent the gradient of MP pollution found in real environmental conditions.