The Impact of Ecological Nano-Calcium from Eggshells as an Alternative Calcium Source on Calcium Nutrition and Oxidative Stress Mechanisms in Lettuce Grown Under Saline and Boron Toxic Conditions

Abstract Nano-fertilizers with higher efficacy compared to conventional fertilizers can provide advantage for plant cultivation in both productive and problematic soils. Therefore, this study aimed to determine the effect of nano-calcium (nano-Ca) on lettuce plants grown in saline-boron (B) toxic soil. Nano-calcium fertilizer was prepared from eggshells. Functional and structural properties of nano-Ca was determined by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) before plant experiment. The treatments was; control, 40 mM NaCl and 20 mg kg− 1 B (NaCl + B), and 40 mM NaCl and 20 mg kg− 1 B with 4 mM Nano-Ca (NaCl + B + nano-Ca). The nano-Ca significantly increased the dry weight and calcium (Ca) concentration of lettuce plants under saline-B toxic conditions. Although there was a decrease in the concentrations of sodium, chloride, and B with nano-Ca application, it was not statistically significant. Due to salinity and B toxicity, the level of malondialdehyde (MDA) as a measure of lipid peroxidation and hydrogen peroxide (H2O2) concentration decreased significantly with nano-Ca application. The catalase activity (CAT) increased with nano-Ca application, while the ascorbate peroxidase (APX) activity decreased, and there was no significant change in superoxide dismutase activity (SOD). The results obtained from the study indicate that nano-Ca plays a protective role for lettuce plants grown saline-B toxic conditions.