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Rapid depletion of groundwater and climate change mediated shifting precipitation pattern is forcing farmers to look for alternative irrigation options like wastewater. However, routine irrigation with trace metal contaminated wastewaters could potentially pollute soil as well as cause health risks through the consumption of food products grown in contaminated soil. Thus, the present study aimed to investigate the trace metals build-up status in topsoil and potato (Solanum tuberosum L.) tubers upon continuous irrigation with coalmine effluent contaminated wastewater compared to irrigation with groundwater and surface water over three consecutive years. Soil pollution status and human health risk associated with consumption of potato tubers grown on wastewater-irrigated soil was also assessed in this study. Three separate experimental sites differing in irrigation source (groundwater, surface water, and coalmine wastewater) were selected near Barapukuria Coal Mining Company Limited located at Parbatipur upazilla of Dinajpur district, Bangladesh. Nine trace metals namely arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were estimated. Results showed significantly higher trace metal content in both soil and potato tubers due to wastewater irrigation. Wastewater suitability for irrigation regarding Cd, Cr, Cu, Fe, Ni and Pb were off the permissible level although the soil contamination with trace metals and their levels in potato tubers remained within the safety limit. Health risk assessment revealed that, consumption of potato tubers grown in wastewater-irrigated soil remained safe although health risk associated with Cr was almost at the border. The study exclusively highlighted the core massage that, trace metal contamination of both soil and potatoes cultivated in them was increasing alarmingly due to three years of wastewater-irrigation. Although the extent of contamination was below critical limit, it can potentially become hazardous in years to come unless wastewater-irrigation is checked. This study was successful to provide valuable insights regarding the potential environmental and human health threats that might arise due to unmindful irrigation of contaminated coalmine wastewater. Besides, this study should prove useful in strategizing safety measures for cropping under trace metal contaminated soils and for planning industrial effluent disposal to avoid agricultural soil contamination.

Potato (Solanum tuberosum L.), world's fourth most carbohydrate supplying crop is often challenged by numerous pathogens among which Sclerotium rolfsii remains one of the most damaging during both growth and storage. As biocontrol is being preferred for their safety and sustainability, the present experiment was conducted for testing the biocontrol effectiveness of microencapsulated Trichoderma harzianum application in combination with organic additives against S. rolfsii. Five combinations (no T. harzianum+no organic additive [control]; T. harzianum+no organic additive; T. harzianum+rice husk biochar; T. harzianum+mustard oil cake; and T. harzianum+tea waste) were tested against two levels of S. rolfsii (absence [control] and presence) under a polyhouse environment. Prior to that, hyper-parasitism of T. harzianum against S. rolfsii was tested in vitro which showed 63.2% growth inhibition for the later. Polyhouse study revealed 16%, 25%, 19%, 21%, 38%, 27%, 9%, 13%, 28%, 20% and 9% average increase in plant height, branch number plant–1, leaf number plant–1, shoot dry matter, root dry matter, healthy tuber, total tuber yield, leaf greenness, net photosynthetic rate, total phenolic content and total antioxidant activity respectively with a subsequent reduction of 49% unhealthy tuber and 32% disease severity index due to T. harzianum+organic additive treatments. Disease suppression and growth recovery of S. rolfsii inoculated potato plants were found significantly better when T. harzianum was applied with organic additives compared to solitary application. The results of this study would provide useful information in strategizing T. harzianum formulation preparation for effective biocontrol of potato stem rot caused by S. rolfsii.