Screening of Tomato Genotypes for Resistance to Early Blight (Alternaria Solani)

Early blight disease caused by Alternaria solani has been a serious problem in tomato growing areas particularly at humid tropical, subtropical and temperate regions of the world. An investigation was carried out at Horticulture Experimental farm, AAU Jorhat with forty-five genotypes of tomato. The experiment was conducted consecutively for two years during Rabi seasons of 2012-13 and 2013-14 in replicated trails. The site of the experiment was a sick plot where tomato was grown continuously for three years before testing the genotypes. Recommended package of practices were followed to raise the crop. Blight incidence was evaluated from the disease symptoms using Percent Disease Index (PDI) after the genotypes were artificially inoculated with isolates of A. Solani. The genotypes Sel-35 (TLBRH-6 X Konbilahi) and Sel-19 (TLBRH-6 X Konbilahi) were highly resistant, 7 were resistant, 14 were moderately resistant, 16 were susceptible and 6 were highly susceptible. The result was found to be similar for both the years. The loss in yield due to the disease ranged from 2.15 % in highly resistant genotype to 42.75 % for highly susceptible genotype. Disease resistant genotypes along with high productivity could be evolved by incorporating resistant trait present in highly resistant genotypes to high yielding genotypes.