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Variations in morphological and physiological traits of wheat regulated by chromium species in long-term tannery effluent irrigated soils
- Riaz, Muhammad, Yasmeen, Tahira, Arif, Muhamad Saleem, Ashraf, Muhammad Arslan, Hussain, Qaiser, Shahzad, Sher Muhammad, Rizwan, Muhammad, Mehmood, Muhammad Waqas, Zia, Afia, Mian, Ishaq A., Fahad, Shah
- Chemosphere 2019 v.222 pp. 891-903
- agricultural soils, bioaccumulation factor, carotenoids, chlorophyll, chromium, growth and development, organic carbon, organic fertilizers, physiological response, phytotoxicity, plant growth, pollution, soil sampling, tannery effluents, wastewater irrigation, wheat, Pakistan
- Tannery effluents are rich source of chromium (Cr) and organic carbon (C), however, hexavalent Cr (Cr6+) is many-fold more toxic than trivalent Cr (Cr3+). We examined the extent of total Cr, Cr3+ and Cr6+ pollution of agricultural soils under long-term tannery effluent irrigation in Kasur, Pakistan. Effects of Cr species on morphological and physiological responses of wheat including patterns of Cr3+ and Cr6+ uptake, their translocation factor (TF) and bioconcentration factor (BCF) were studied. Nine soil samples had significantly variable total organic C and total Cr, Cr3+ and Cr6+ contents. Pot study showed that morphological characteristics of wheat were largely unaffected by total Cr, Cr3+ and Cr6+ contents, however, physiological responses including contents of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids and total proteins; and chlorophyll a:b ratio were significantly affected by contents of Cr species. Results further suggested that the relationships between total Cr and physiological attributes of wheat were controlled by Cr6+ rather than Cr3+ contents and, hence, Cr3+:Cr6+ ratios determined the effects of Cr on wheat growth and development. Uptake, TF and BCF values for Cr3+ and Cr6+ showed significant variations and BCF values showed negative correlation with total organic C contents. Results of our study highlight the significance of understanding the effects of Cr species and Cr3+:Cr6+ ratios rather than the total Cr contents when assessing the Cr behavior in soils and its effects on plant growth, especially phytotoxicity of tannery-based organic fertilizers before its application in the field.