Employing different parameters of disease epidemics for screening and assessment of tomato genotypes against early blight disease

Early blight is the most devastating fungal disease that infects tomato (Solanum spp.) caused by Alternaria spp. Screening of a panel of fifty-one tomato lines comprising some wild relatives for resistance against early blight was carried out under uninoculated natural field conditions and under artificially controlled conditions where the latter was found to be more informative. Disease intensity was recorded at different time intervals under both conditions following Pandey's 5-point scale to find out the percent disease intensity (PDI) and area under disease progress curve (AUDPC). Under the influence of constant inoculum load, disease intensity was found to increase with the age of plants. A positive association was shared between PDI and AUDPC while resistance was found to be negatively correlated with AUDPC. A parallelism in genotype performance was found for screening results and AUDPC under both conditions. Resistant genotypes can be utilized in future breeding schemes for producing hybrids resistant to early blight.