Multiplication of Pseudomonas solanacearum in Rhizosphere and Root Tissue of Susceptible and Resistant Varieties of Solanum melongena

Abstract

AbstractThe population build‐up of Pseudomonas solanacearum in the rhizosphere, and root‐tissues of two egg plant varieties, susceptible and resistant, raised in infested soil was investigated at different stages of plant growth. There was no perceptible difference in the population build‐up of the pathogen in the non‐rhizosphere soils of both the susceptible and resistant plants. However, the soil 3 cm away from the tap root of the susceptible variety contained a higher population of the pathogen compared to the soil similarly drawn from the resistant plants. The pathogen population in the rhizosphere of the susceptible variety increased 1,000‐fold with increasing age of the plant and was highest at flowering. The rhizosphere of the resistant plant, showed only a 10‐fold increase in pathogen population. The trend was similar with the root tissue populations of the pathogen, but the differences in the root tissue populations of the resistant and susceptible plants were more pronounced. Considerable, buildup of the pathogen population in the susceptible variety was also seen in the above ground portions of the plants. Root extracts of the resistant variety had a marked inhibitory effect on the growth of the pathogen.