Effects of Fly Ash Amended Soil on Biochemical Attributes and Antioxidant Responses of Medicinally Potent Plant Calendula Officinalis

Abstract

Phytoremediation of fly ash (FA) deposits using metal tolerant plant species has become an important eco-friendly technique for reclamation nowadays. The present study was carried out to determine the impact of FA application on photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids), biochemical parameters (soluble protein, reducing sugar, nitrate and nitrate reductase (NR) activity), metal accumulation (Fe, Zn, Cu, Co, Cd, Cr, and Mn) and antioxidant defense activity (SOD, CAT, POD, and APX) of Calendula officinalis. With this aim in mind, under pot culture conditions, Calendula officinalis was grown in different combinations of FA and soil which include: Control, 10%, 20%, 40%, 60%, 80%, and 100% FA. The results from the study indicated that the addition of FA (40%) in soil not only improved the physico-chemical properties of soil but also increased the photosynthetic pigment and other biochemical parameters in plants, however, these parameters declined under high FA applications. On the other hand, antioxidant enzyme activities (SOD, CAT, APX and Peroxidase) of Calendula increased with increasing FA application to combat heavy metal stress from fly ash. At high FA applications, antioxidant enzyme levels increased in leaves thereby reflecting heavy metal stress and mitigation of reactive oxygen species.