Systematic Evaluation of Groundnut Genotypes for Resistance to Cercospora Leaf Spot Disease

Abstract

The present study assessed peanut genotypes for resistance to Cercospora leaf spot (CLS), with a focus on disease severity and defoliation across different growth stages. Based on Percent Incidence Data (PID) and defoliation scores, genotypes were classified as susceptible, moderately resistant, or resistant. Disease progression was measured through the Area under the Disease Progress Curve (AUDPC), revealing significant variation in resistance among the genotypes. Most genotypes, including 21CG001, 21CG002, 21CG003, 21CG004, 21CG006, ATTOCK 19, and 20AK012, exhibited high PID and defoliation levels, with AUDPC values indicating susceptibility. Their PID ranged from 23.96 to 31.72 at 50 days after sowing (DAS) and from 44.84 to 56.97 at 70 DAS. Genotypes 21CG005, 20AK004, and ATTOCK 19 showed the highest PID and defoliation levels, with AUDPC values over 320, categorizing them as highly susceptible. Conversely, genotypes 21CG007, 21CG008, 20AK001, and 20AK010 demonstrated the lowest PID, minimal defoliation, and AUDPC values below 250, indicating strong resistance. In vitro trials further highlighted variability in lesion characteristics, with genotypes 20AK012, BARI 16, and 20AK010 showing the most severe symptoms, including rough lesion textures and types ranging from minute chlorotic spots to mature black lesions. Overall, genotypes 21CG007, 21CG008, 20AK001, and 20AK010 exhibited high resistance, while ATTOCK 19, 20AK004, and 21CG005 were highly susceptible. These findings underscore the importance of selecting resistant genotypes for effective CLS management in peanut cultivation.