Investigation of the usability of ornamental kale in rehabilitation of coal mine wastes

Mining activities are considered among the sources of environmental pollution, as they lead to the release of heavy metals and other toxic compounds into the environment. These activities pose significant ecological risks to soil, water and vegetation, thereby negatively affecting overall ecosystems. Therefore, the development of environmental strategies for monitoring, controlling and reducing mining-related pollution is a necessity. In this study, the ornamental kale (Brassica oleracea L. var. acephala) cultivars Kamome Red F1, Kamome Pink F1 and Kamome White F1 were used to investigate their potential for the remediation of coal mine waste. For this purpose, growth media containing different concentrations of coal mine waste (0, 10%, 20%, 40% and 60%) were prepared and a total of 60 pots were established with four replicates for each cultivar and each treatment. In all prepared growth media, analyses of saturation, lime content, salinity, pH, organic matter and macro and micro element concentrations were conducted. In the cultivated and harvested plants, analyses of shoot length, fresh and dry weight, chlorophyll pigment contents, proline level, lipit peroxidation and electrolyte leakage were performed; additionally, catalase (CAT) and superoxide dismutase (SOD) gene expression levels were determined from leaf tissue samples. The findings indicated that increasing the proportion of coal mine waste in the growth media led to pronounced changes in their physical and chemical properties. Among the cultivars, Kamome White F1 exhibited the most stable growth response and was identified as the most tolerant to stress conditions. Chlorophyll contents generally showed limited variation and the preservation of pigment levels particularly in the Kamome White F1 cultivar indicated that photosynthesis was less affected under stress conditions. While an increase in proline was observed in the Kamome Red F1 cultivar under high coal mine waste applications, the low malondialdehyde concentrations and electrolyte leakage values in the Kamome White F1 cultivar revealed that membrane damage was more limited. CAT and SOD gene expression levels reached their highest values in all cultivars, particularly in the environments containing 20% and 40% mine waste. When all data were evaluated together, it was concluded that the Kamome White F1 cultivar exhibited the most stable physiological, biochemical and molecular response to coal mine waste.