The Effect of Zinc Oxide Nanoparticles and Salicylic Acid on Controlling Powdery Mildew of some Barley Genotypes in Egypt

This study was carried out in two different agro- ecological zones, in terms of climatic conditions at Sakha and Giza Research Stations during season 2022/2023, on two different barley genotypes, Line 1 and Line 2, to evaluate the effectiveness of zinc oxide nanoparticle (ZnO-NPs) at three concentrations (100, 50, and 25 mg/L) and the organic acid, salicylic acid in managing powdery mildew caused by Blumeria graminis in barley. The systemic fungicide Raxil S was used as a reference treatment.The most effective treatment for reducing disease severity in the greenhouse was the fungicide, achieving a 92.50% for line2 and90.59% line 1 disease reduction, followed by the Zno100 ,50,25 mg/L concentrations and salicylic acid , Additionally, the highest chlorophyll levels were observed in the plants treated with the fungicide Raxil S, followed closely by ZnO100. Both treatments also led to increased levels of phenols and enzymes, further enhancing their protective effects against the disease. In field trials conducted, at Sakha and Giza Research Stations for the Line 2 genotype, the most effective treatments for achieving a good crop yield were the fungicide Raxil S, followed by the nano-zinc oxide compound at a concentrations of 100 .50 and 25ml/L and salicylic acid. The results revealed that the average disease severity percentages for the treatments, the fungicide Raxil S, Zno100 mg/L, and Zno50mg/L showed disease severities of 5, 5.4, and 5.9%, respectively, compared to control, which had a significantly higher severity of 21.8 %. Similar trends were observed for the Line 1 genotype.. Regarding genotype sensitivity, Line 1 demonstrated greater susceptibility to infection by powdery mildew compared to Line 2