Effect of inoculum load and duration of exposure to Macrophomina phaseolina on disease incidence of sesame

Abstract

An experiment was conducted to critically evaluate the impact of inoculum load as well as duration of exposure to pathogen on disease incidence. The maximum germination percentage (27.5%), minimum seed rot (72.5%), maximum seedling mortality (20%) was found at lowest inoculum level of 2g/kg. In contrast to that, lowest germination% (12.5%), maximum seed rot (87.5%), less seedling mortality (12.5%) and no survival of plants was obtained at high inoculums level of 10g/kg of soil. Seed soaking of 24 hours in culture filtrate registered minimum germination (5.0%), maximum diseased seed (95%), short seedling length (3.8 cm) and low vigour index (18.6). The lowest hour of seed soaking of 4 hours recorded maximum germination (11.0%), minimum disease (86.0%), high seedling length (5.9cm) and high vigour index (64.0). It is evident from experiment that, Germination per cent of test plant was gradually decreased with increasing inoculum level and duration of exposure to pathogen. The seed rot and seedling mortality increases with increasing inoculums load. It also affects the survival of seedling as well as reduce seedling length and vigour index.