الفهرس 
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Abstract
Two field experiments were carried out during successive agricultural season (2021-2022) on a private farm at Abu-Zabal County, El- Qalyubia Governorate (N 30° 14’ 58” and E 31° 21’ 16”), Egypt. Spinach experiment was conducted to test the effect of isolated heavy metals-resistance bacteria (soil application) as well as foliar spray with silicon dioxide nanoparticles (Si-NPs) and moringa leaf extract (MLE) on production, antioxidant defenses, and physio-biochemical characteristics of spinach plant grown on heavy metal contaminated soil. Bacteria and MLE or Si-NPs have been applied in single or combined treatments. Data revealed that all single or combined additions increased (p <0.05) plant height, shoot dry and fresh weight, leaf area, number of leaves/plant, leaf contents of photosynthetic pigments, total soluble sugars, free proline, membrane stability index, ascorbic acid, relative water content, α tochopherol, glycine betaine, glutathione, and antioxidant enzyme activities (i.e., peroxidase, glutathione reductase, catalase, superoxide dismutase and ascorbate peroxidase) compared to the control treatment. However, plant leaves content of contaminants (Fe, Mn, Zn, Pb, Cd, Ni, and Cu), malondialdehyde, electrolyte leakage, O2•−, and H2O2 were significantly decreased. Wheat experiment was conducted to study the effect of isolated heavy metals-resistance bacteria as well as application of vermicompost, biochare and potassium silicate on plant growth, yield, antioxidant defenses, and physio-biochemical characteristics of wheat plant grown on heavy metal contaminated soil. Single application of bacteria strain Bacillus subtilis (Bs) resulted in the highest plant height, leaf area, straw yield and grain yield as compared with all single applications of other bacteria strains; Paenibacillus jamilae (Pi) and Pseudomonas aeruginosa (Psa). Combined applications of bacteria strains and other soil amendments improved plant growth attributes, straw and grains yield and antioxidant defenses more than single application. The application of Bacillus subtilis accompanied with potassium silicate was the best treatment in the maximum Ch a (2.16 mg g-1), Ch b (0.98 mg g-1), Carotenoids (0.44 mg g-1), RWC (81.7 %) and MSI (62.4%), while these parameters recorded their lowest values (1.09, 0.31, 0.28, 58.8 and 33.6, respectively) as comparing with other combined applications. All soil amendments even single or combined with Bs, Pi, Psa, vermicompost, biochar and potassium silicate reduced soil content of heavy metals (Fe, Mn, Zn, Pb, Cd, Ni, and Cu) significantly. The combined application of Bs and potassium silicate resulted in the minimum contents of Fe, Zn, Cu, Mn, Pb, Cd and Ni in straw and grains of wheat plants. A pot experiment was carried out on lettuce (Lactuca sativa L.) for growing 2021 season to study the effect of various water sources i.e., fresh water (FW), agricultural drainage (ADW), sewage (SW) and industrial drainage water (IDW) after treated with moringa seed extract (MSE) on removing water and soils contamination and its effect on yield and heavy metals content of lettuce plants. The lowest values of SSP, SAR, SCAR, RSC, RSBC, PI, PS, KR and MAR were obtaind in fresh water followed by industrial drainage water, sewage water and agricultural drainage water when treated with MSE. The classification of all water sources indicates before treated with MSE of high salinity-low sodicity (C4S1) and moderate low sodicity (C2S1) after treated with MSE. Addition of MSE to water soureces reduced water turbidity, NO3-N, BOD, COD, DO and heavy metals compared with untreated water. The highest values of fresh and dry weight, N, P and K- uptake of lettuce plants obtainted in different water sources treated with MSE. Addition of MSE to different water sources gave the lowest accumulation of Pb, Cd, Ni, Fe, Cu, Zn and Mn in soil and lettuce plants compared to untreated water.