Zeolite amendment reduces lead accumulation and improves growth and yield in tomato plants irrigated with sewage water

Although sewage water (SW) is a source of nutrients, it also causes heavy metal accumulation in soil; especially, lead (Pb⁺) contamination of soil is a serious concern in agriculture. Soil contaminants limit the bioavailability of nutrients to plants. So, they affect plant growth and produce quality. Therefore, a pot experiment was conducted to investigate the effect of zeolite soil amendment on the accumulation of Pb⁺ in tomato crop grown with SW irrigation. The pot media of SW-irrigated plants was amended with different concentrations of zeolite, viz., 0.75%, 1.50%, and 2.25%. The results showed that the application of 0.75% zeolite increased leaf area, plant height, fruit number, and plant fresh and dry biomasses by 37%, 17%, 14%, 24%, and 7% compared to freshwater irrigation. Moreover, the lowest zeolite dose also led to higher chlorophyll content (68.02 SPAD) compared to SW-irrigated plants (55.13 SPAD). Similarly physiological traits, such as A, gs, and E, were higher (17.68 µmol m^-2 s^-1, gs 0.28 mmol m^-2 s^-1, and 7.88 mmol m^-2 s^-1, respectively) in 0.75% zeolite-treated plants than in SW-irrigated plants (12.99 µmol m^-2 s ^-1, 0.19 mmol m^-2 s^-1, and 7.00 mmol m^-2 s ^-1, respectively). On the contrary, a reduced level of hydrogen peroxide and malondialdehyde and decreased activity of antioxidant enzymes were observed in low-dose zeolite applied plants. Zeolite reduced Pb⁺ accumulation in tomato plants as compared to SW-irrigated plants, whereby Pb accumulation in the fruits of SW-irrigated plants was 80% more than those of zeolite + SW-treated plants. Conclusively, this study has revealed the improvement in morphological and physiological growth attributes of the SW-irrigated tomato plant in response to zeolite application.