## 1 Introduction
Grassland was quantitatively analyzed in terms of the physicochemical properties of soil, the multitude and diversity of plant species, and the soil seed bank. This work pointed out that a decrease in total soil nitrogen could explain 13% of the changes detected in plant abundance, while soil pH and 0.05 M Ethylene diamine tetraacetic acid (EDTA) extractable copper explained 10% and 7%, respectively. Furthermore, it was found that this pollution had affected the regeneration ability of the native plant species from the soil seed bank and the seed distribution in the soil [11]. For instance, [PERSON] et al. [12] determined copper concentrations in 22 different native species near the Ventanas smelter in order to compare copper concentration levels (200 and 600 mg kg\({}^{-1}\)) in these species, aiming at identifying the hyperaccumulator plants representative of Chilean conditions. Although no hyperaccumulator native plants were found, _Oenothera picensis_ (treated as _Oenothera affinis_ [12], hereinafter referred to as _Oenothera picensis_ [13]) was considered a good candidate for remediation initiatives in this area [12]. Moreover, [PERSON] et al. [14] monitored copper (9.3 and 8.6 mg kg\({}^{-1}\)) and selenium (0.1 and 0.4 mg kg\({}^{-1}\)) concentrations in rainwater, soils, and _Medicago sativa_ samples at various sites from three different zones of the Valparaiso region, including the Puchuncavi valley. In this case, a close correlation between copper concentrations in soil and _Medicago sativa_ samples was found as a function of the distance from the smelter [14]. Staying focused on phytoremediation purposes of Puchuncavi valley, [PERSON] et al. [15] studied the low molecular weight organic acid (LMWOA) root exudation pattern and Cu accumulation capability in the shoot and root tissues of two native Chilean metallophytes (_O. affinis_ and _Imperata condensata_) and two agricultural plants (_Lupinus albus_ and _Helianthus anmus_). These plants were grown under hydroponics conditions at increasing copper levels and analyzed after harvesting. All the plant species showed high Cu accumulation, among which the metallophyte _O. affinis_ was found to be the most tolerant species (116 and 2657 mg kg\({}^{-1}\) Cu in shoots and roots, respectively). Additionally, they stated that the LMWOA root exudation is a crucial Cu tolerance mechanism developed by metallophytes that should be considered as an important factor for plant selection in phytoremediation programs [15]. Regarding the _O. picensis_ species, further studies were carried out by [PERSON] et al. [16] to evaluate the effects of liming and nitrogen fertilization on its cotyledon emergence, survival, biomass production, and copper accumulation. In this case, _O. picensis_ (named _O. affinis_ in this work) was grown in soil from Puchuncavi valley, but in controlled conditions. These results showed that liming decreased Cu concentration and Cu\({}^{2+}\) activity in the soil solution, whereas nitrogen fertilization increased the concentration of Cu in roots and shoots in limed soils. Therefore, they concluded that liming is sufficient to improve soil conditions for the development of _O. picensis_ in acid- and metal-contaminated soils, allowing its potential use for phytostabilization [16]. Similarly, [PERSON] et al. [12] evaluated the effects of the biodegradable chelate of methylglycienediacetic acid (MGDA) on copper extraction by _O. affinis_ by [PERSON] et al. [12]) through acid soil samples from Los Maitenes (Puchuncavi valley). In this case, MGDA application, which was added at four different rates, 0 (control), 2, 6 and 10 mmol plant\({}^{-1}\), considerably increased biomass production and copper extraction from 0.09 mg plant\({}^{-1}\) (control) to 1.3 mg plant\({}^{-1}\) (in the 6 and 10 mmol plant\({}^{-1}\) treatments). In this sense, they demonstrated that applications of MGDA are an effective and environmentally safe way to improve copper extraction by _O. picensis_ in these soils [13]. Recently, [PERSON] et al.