Detoxification of MG may be achieved through some metabolic activities present in the roots

According to those findings, there was an elevated nitrogen content in the shoot tissue of the plants, while plant growth was inhibited; in the current study the elevated level likely reflected an increase in stress responses upon exposure to MG. Several plants species have potential for dye decolorization. The decolorization of either the textile effluents or dye mixtures used can be achieved by adsorption and accumulation on plant surfaces, and mostly by phytotransformation or phytodegradationdthe mechanism that degrades or transforms the dye into non-toxic products. The degradation could be enhanced by rhizosphere-associated microorganisms, by enzymes excreted from or within roots  or even by enzyme extracted from leaves  and cell cultures. In the current study, the adsorption of the MG dye to root surfaces, as could be seen by the blue staining, particularly in the treatments with MG of 2 mg/L or 4 mg/L, could be one mechanism that accounts for the depletion of MG dye in the growth solution that occurred in this study. According to Davies et al.,adsorption of xenobiotics followed by its absorption, allows the binding of xenobiotics to plant roots. Retarded roots of B. chinensis growing with MG at 2 mg/ L or 4 mg/L suggests toxicity of MG to plant roots. It has been reported that B. juncea has great potential for Reactive Red 2 degradation which is supported by the activities of the enzyme laccase and NADH-DCIP reductase predominantly present in roots. Nevertheless, Mukherjee and Das  reported that the decolorized level of MG by Enterobacter asburiae Strain XJUHX-4TM decreased as the exposure time and concentration of the dye increased due to the toxicity of the dye to bacterial cells.However,hydroponic nft the 28 d of exposure used in the current study and at higher concentrations  may have caused a reduction in the detoxification ability of the plant and resulted in plant toxicity.

The results obtained from the FTIR analysis can be used as a tool to predict the changes in the functional groups of the original dye molecules. The ATR-FTIR analysis was performed in the study to detect whether or not there were functional groups possibly obtained from MG that had accumulated in the edible plant part. The ATR-FTIR spectra comparison between plant samples from the control and treatment groups suggested that at the concentration of 1 mg/L, MG may be transformed before either being taken up by the plants or translocated into the shoot tissue. Kagalkar et al.  showed that Blumea malcolmii Hook. could degrade MG dye and the degradation gave 4-dimethylaminocyclo-hexa-2,4 dienone as the transformed product. Fu et al.  found that transgenic Arabidopsis converted Crystal Violet to Lleucocrystal Violet,which is non-toxic to the plant, and LCV was then gradually degraded by other endogenous enzyme activities. The products obtained from the phytotransformation of MG were usually non-toxic to tested plant species in all phytotoxicity reports. Hence, this might explain the unaffected growth of B. chinensis in the growth medium with a concentration of 1 mg/L MG, whilst the ATR-FTIR spectra  suggest that there was a similar functional group in MG and in the shoot of plants grown at 2 mg/L MG. Although it might be possible that the functional group originated from MG or could have been obtained from MG degradation, it could also be the substance synthesized by the plant in response to MG. Hence, identification is still needed of the substances, using techniques such as high performance liquid chromatography mass spectrometry. Together with this result, the effects on root growth at MG concentrations of 2 mg/L and above suggested that these concentrations are toxic to root cells and may result in the accumulation of toxic substances in the shoot tissue of B. chinensis. The increased oxalate content in the shoot tissues of plants exposed to MG in the current study might be accounted for by an enhanced tolerance mechanism in the plant, as Nilratnisakorn et al.  suggested that the precipitation of metal-dye complexes in leaves and roots as calcium oxalate, calcium silicate and silica in Typha angustifolia Linn.  is the mechanism that avoids damage to plant cells.

With regard to the potential health risk of some bioaccumulated substances in food products, the accumulation of possibly toxic derivatives obtained from MG transformation such as Leucomalachite Green  in plant tissues still needs to be identified. In addition, as oxalate comprises 75% of kidney stones  and consumption of high oxalate foods can promote the risk of kidney stone formation  in the human urinary tract, B. chinensis grown with MG contaminated water in this study, having increased the oxalate content, may pose a risk of kidney stone formation as well. The results of plant growth revealed that B. chinensis was able to grow in water contaminated with MG at a concentration of 1 mg/L and had the ability to remove the dye from contaminated water through adsorption via its root surface. The tissue contents, total N and total oxalate concentrations, and the ATR-FTIR spectra analyzed in the current study indicated that the tolerance of the plant to low levels of MG could be achieved by increasing stress responses and the accumulation of toxic substances in oxalate form, which hamper toxicity to plant cells. However, the plant could not tolerate high concentrations  of MG resulting in the increased accumulation of toxic substances in plant tissue and the reduction of overall growth as a consequence. A conclusion from the current study is that although the integration of hydroponic plant production for wastewater management in aquaculture that is still using the dye at a low concentration can be applied without noticeable phytotoxicity symptoms, this might pose a potential health risk for humans. Hence, the detection and identification of substances accumulated in plant tissue is still needed.As one interviewee from the Ministry of Agriculture noted “is organic farming sustainable? We think conventional farming is producing sustainable as well and we will support this”. This can be further illustrated by the example of the continued manure problems in the livestock sector, which resulted in a strong exceedance of phosphate emissions in 2018. Based on EU rulings, the Dutch government had to decide reducing the dairy livestock sizes and numerous animals had to be slaughtered. However, organic farmers felt not to be responsible for this problem, while also an expected shortage of organic manure was expected.

In 2018 organic farmers’ associations started a lawsuit against the Dutch government, supported by positive findings of the EU commission on Environment. However, strong resistance came from the conventional Dutch agricultural association which led to the governmental decision not to handle organic livestock differently . As a result, also many organic dairy cows were slaughtered. Regarding the 19 reported barriers, two barriers were identified as high priority , eight barriers a medium priority and seven barriers a low priority . Within the function market formation that accounted for 37% of all barriers, the barrier ‘lack of demand’ was mentioned most often; by 10 of the 13 respondents, and with 77% of high priority. Within the function guidance of the search, one barrier had a high priority , and four had a medium priority. The barrier of the ‘vision on economic growth and export’ was mentioned by 9 of the 13 respondents. Within the function resource mobilization three barriers were identified; two with medium priority and one with low priority. Function F1 accounted for only one medium priority barrier. The functions F2 and F3 had one medium priority barrier and the function F7 one low priority barrier.The observed barriers may lead to systemic problems in the upscaling of organic dairy farming, since they relate both to soft and hard institutional failures . From the first national organic memorandum the Dutch policy vision was to develop the demand side while regular market mechanisms would result in a larger supply and hence an increase of organic dairy farmers. Newspaper articles published at that time were very critical regarding the implementation of the policy. Those articles stated that the Minister of Agriculture relied heavily on market forces and it was questioned whether it could lead to upscaling while price differences between organic and conventional goods remained high. A hard institutional failure can be found in the interplay between the Ministries of Agriculture and Environment . While the Ministry of Environment embraced the sustainability targets of organic farming it did not support this with policy instruments, while within the Ministry of Agriculture the incumbent socio-technological regime blocked specific support to organic farming .

Moreover within the functions ‘market formation’ and ‘entrepreneurial activities’ persistent capacity and capability problems can be identified. First, the lack of consumer demand and lack of stimulation of the consumer were strong barriers. Although earlier organic products could only be purchased through a few specialty shops, this was no longer the case in the second half of the 1990s. Yet from 2010 onwards, newspaper articles also reported a lack of organic supply, and supermarkets had to import organic dairy from other EU countries. Despite this imbalance, some newspaper articles as well as a number of respondents indicated low consumer willingness to purchase organic products due to higher prices. Second, the ‘free-market’ approach also led to a capacity problem of farmers or how Smith states it, a transition problem. This problem was mainly enforced by a hard-institutional failure of lacking transition subsidies, and a soft institutional failure of lacking moral support to farmers during the transition stage. Danish respondents rated the factor ‘goals and initiatives’ an 80% priority as the Danish government has facilitated strongly the development of the sector. By 1986, the Danish Ministry of Agriculture showed an explicit interest in organic farming. This led amongst others to administering of the red Ø-label, hydroponic channel providing subsidies for farmers and a strong support for development and innovation initiatives . Farmers not only received subsidies for the transition phase, but also received environmental subsidies . In 1995 Denmark introduced its first national action plan to promote organic farming. The progress of this action plan was monitored closely and led to a considerable increase in cultivated areas. In 1999 a second action plan was announced with the main goal obtaining a 10% share of cultivated agricultural land . In 2011 ‘The Organic Action Plan 2020’ was introduced. The main goal of this action plan was to double the organically cultivated area by 2020. To realize this plan stakeholder involvement was a necessity. By 2007 this led to a gradual shift from only ‘supply side’ subsidies towards more ‘demand side’ subsidies. More funding was allocated to research, sales promotion, and purchase subsidies for local government canteens, kitchens and hospitals to supply 60% with organic products . Moreover, on the ‘supply side’ also pesticide taxes were introduced that had a direct but moderate effect on the organic sector . Since the implementation, organic farmland has grown by 57% and organic retail sales doubled . Due to these implementations the organic sector went from a small group of self-regulated farmers to a large group of strong legally regulated farmers . Also Austrian respondents rated the factor ‘goals and initiatives’ key in the development of the organic sector . Austria joined the EU in 1995, and faced a low competitive agricultural sector . This was due to the less productive mountainous environment that also resulted in relatively small household farms. The government therefore prepared the sector by “promoting conversion to organic farming as a general strategy for the survival of Austrian agriculture”. Well before the EU accession, farmer organizations, such as the ‘Ernte’ association, developed organic principles independently from the EU regulation . Since its accession and from 2001, Austria continuously implemented organic action programs. These action plans were established to enhance the development of the Austrian organic agriculture sector. Currently the 5th action plan is in place to maintain Austria’s largest share of organic farmland within the EU . In 1987, Denmark introduced conversion subsidies for organic farmers. According to 80% of the respondents, these subsidies enhanced the growth of the organic dairy sector in Denmark. Between 1989 and 1994 the subsidies were mostly aimed at livestock producers .