الفهرس 
: Importance and Productivityugar beetII.
Evaluation the resistance of sugar beet cultivars to powdery mildewOnly 14 pages are availabe for public view
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Abstract
Sugar beet (Beta vulgaris L.), is one of the most important crops for human nutrition and sugar production all over the world. Powdery mildew which is caused by Erysiphe betae, is one of most important disease which attacked it. It is considered the most serious disease-causing yield losses. The present study was conducted to investigate the potential role of some chemical inducers for inducing resistance in sugar beet plants against powdery mildew disease through two experiments. The first experiment was conducted under greenhouse conditions to investigate the susceptibility of the sugar beet cultivars to powdery mildew. The cultivar Puma was the most resistance. While cultivar Top, was the most susceptible one. The second experiment was carried out to investigate the effect of some chemicals in inducing the resistance to powdery mildew. Fungicide ”Opera” at (1cm) concentration, zinc-oxide nanoparticles (ZN) at concentrations of 100, 50 and 10 ppm and zinc sulphate (ZS) at concentrations of 100, 50 and 10 ppm were effective in reducing sugar beet powdery mildew caused by(E. betae) with comparison to systemic fungicide ”Opera”. Most treatments significantly increased levels of chlorophyll a, b and total chlorophyll, total soluble sugars, endogenous H2O2, and activity of peroxidase (POD) and polyphenol oxidase (PPO). In contrast, were obtained lipid peroxidation (as malondialdehyde ”MDA”), phenolics concentrations and catalase activity significantly decreasing in response to exogenous elicitors. Furthermore, all treatments significantly reduced the severity of powdery mildew disease with a remarkable enhancement of sugar beet yield compared to infected control. ZN at concentrations of 100 and 50 ppm was perior in this respect. The physiological role of these elicitors for inducing resistance against powdery mildew disease may be due principally to relate production andaccumulation of reactive oxygen species (ROS), and oxidative reactions of phenolic compounds catalyzed by PPO and/or POD. In conclusion, ZnO nanoparticles at 100 and 50 ppm could be recommended as foliar spray for reducing the deleterious effects of biotic stress caused by E. betae in sugar beet plants through inducing resistance to this pathogen. Keywords: Sugar beet, Powdery mildew, Nano zinc-oxide, Zinc sulphate.