EFFECTS OF MAJOR SESAME PATHOGENIC FUNGI ON CHLOROPHYLL CONTENT AND FOLIAR DISEASE OCCURRENCE ON TWO SESAME

Abstract

This study evaluated the growth performance and responses of two sesame varieties, Ex Sudan and Gwagwalada Local, to three fungal pathogens under screenhouse conditions. The experiment was conducted in a screenhouse at the University of Abuja Teaching and Research Farm, Nigeria, using a 2 × 3 factorial arrangement in a Completely Randomized Design (CRD) with four replications. We inoculated two sesame varieties with Alternaria sesami, Cercospora sesami, and Helminthosporium sesami, along with control, which was the uninoculated plot. Growth, disease incidence, severity, and using Soil Plant Analysis Development (SPAD), chlorophyll were assessed periodically and analysed using ANOVA and correlation analysis. Following inoculation, disease incidence and severity increased from 7 to 21 days after inoculation (DAI). At 21 days, Helminthosporium produced the highest disease incidence (96.38%) and severity (85.38%), followed by Cercospora (77.00%; 62.38%) and Alternaria (60.75%; 45.63%), while controls remained minimally affected. All pathogens reduced chlorophyll content, with Helminthosporium causing the greatest decline (24.3%) in Gwagwalada Local Variety. There was no significant difference (p ≥ 0.05) in the disease infection responses between the two sesame varieties. Variety and variety × pathogen effects were non-significant, indicating comparable disease responses. Chlorophyll content at 21 days was strongly negatively correlated with disease incidence (r = - 0.824) and severity (r = - 0.803; p < 0.05). The findings demonstrate differential pathogenicity among the fungi and establish SPAD chlorophyll measurements as a useful nondestructive indicator of disease-associated physiological stress. Future investigations  should include field validation of the current findings.