Materials And Methods
The present study was conducted at two growing seasons from autumn to spring of 2008/2009 – 2009/2010 to screen six different genotypes of tomato against natural infection of early blight disease that caused by Alternaria solani. Seedling were sown in greenhouses and in the field of the experimental farm of Maryout Research Station, Desert Research Center, and Alexandria Governorate. Seeds of NCEBR-6 as a resistant cultivar to early blight were kindly provided by Dr. John I. Yoder, Professor of tomato breeding at the vegetable crops department, California University, Davis, USA and the other five seeds of varieties or inbreed lines were provided by Dr. R. Chetelat, Professor of tomato breeding at Tomato Genetic Resource Center, California University, Davis, USA, The pedigree of the tested six tomato genotypes are showed in Table 1.