Effect of beeswax waste biochar on growth, physiology and cadmium uptake in saffron

Abstract

Saffron (Crocus sativus L.) is a medicinal important plant with none information on cadmium (Cd) phytotoxicity. Therefore, this study for the first time elevated the effects of beeswax waste biochar (a novel organic amendment) on Cd uptake, biomass, antioxidant enzymes activities and some physiobiochemical characteristics in saffron exposed to Cd stress. The treatments were consisted four Cd concentrations (0, 3, 6 and 9 mg kg-1 soil) together with four biochar levels (0%, 1.5%, 3.0% and 6% w/w). The results showed that Cd uptake in saffron corm and leaf tissues was significantly elevated by increase in Cd stress, but this parameter in flower and stigma (as edible part of saffron) was unchanged. Application of Cd caused decrease in plant biomass which was found to recover with the amendment of biochar. The translocation factor values were less than 1 in all the treatments, demonstrating saffron can be considered as a candidate plant for cadmium phytostabilization. Cadmium-induced oxidative stress stimulated malondialdehyde content, and activity of superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase enzymes, while biochar application alleviated the oxidative damages. Crocin component was significantly raised along with increase in Cd concentration. Meanwhile, biochar application declined crocin and increased picrocrocin contents. In conclusion, beeswax waste biochar can mitigate Cd toxicity in saffron by inducing soil alkalinization, immobilizing Cd in soil, reducing Cd partitioning in the aboveground tissues and regulating Cd induced oxidative damage, consequently contributing to lowering the potential risks of Cd pollution.