The Effect of Cutflower-Rose Waste Biochar on Morphological Traits and Heavy Metals in Lettuce (Lactuca sativa L. cv. Syaho)

Biochar reduces the bioavailability of a wide range of pollutants, especially heavy metals (HMs).To evaluate the effects of waste biochar of cutflower rose on growth characteristics and accumulation of lead (Pb) and cadmium (Cd) HMs of in lettuce, a factorial experiment, based on completely randomized design, with four replications was conducted. The amount of rose biochar at 3 levels (0, 5 and 10 g/kg), Cd at 3 levels (0, 10 and 20 mg/kg) and Pb at 3 levels (0, 300, 600 mg/kg) were tested. Results showed that the highest amount of leaf area, fresh and dry weight of shoots, and root volume were observed at 5 g/kg level of rose biochar. Increasing the rose-biochar level from 5 to 10 g/kg decreased all traits except height and diameter of shoots. Application of 600 mg/kg Pb decreased the number of leaves, fresh and dry weight of the shoots, fresh and dry weights of roots, and root length by 6.92, 13.38, 18.04, 22.44, 12.66 and 8.61%, respectively, compared to the control treatment. The highest amount of fresh and dry weight of shoots and root volume was observed in 5 g/kg rose biochar and 300 mg/kg Pb treatment, and the least amount of all of the abovementioned traits was observed at the highest levels of biochar and Pb. Increasing the level of biochar from zero to 5 and 10 g/kg and 20 mg/kg of Cd reduced the loss of root Cd by 92.9 and 24.17 percent, respectively. In fact, rose biochar (especially at 5 g/kg level) has improved the lettuce growth characteristics by reducing the bioavailability of Pb and Cd in the soil.