Interactions between Salmonella enterica subspecies Enterica serovar typhimurium and cowpea (Vigna unguiculata variety sinensis) seeds, plants and persistence in hay

Dynamics of persistence of Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium), a common food- and waterborne zoonotic serovar, on cowpea (Vigna unguiculata variety sinensis), a fodder and green vegetable plant, were studied. The findings revealed that S. Typhimurium not only reduced germination of cowpea seed (P < 0.01), but also caused defects in sprouts (P < 0.02). S. Typhimurium inoculation on seeds before sowing had a more pronounced effect (P < 0.01; i.e., loss in germination and appearance of defective sprouts) than sowing seeds in S. Typhimurium-inoculated soil. S. Typhimurium persisted in saplings and adult plants up to 45 days of plant age and up to 60 days in hay. The cowpea plants grown in sterile Salmonella-free soil did not support colonization of S. Typhimurium in different parts. A reduction in the population of Salmonella appeared as early as on the fifth day and decreased with advancing plant age. At 21 days of age, the cowpea plants had no Salmonella in their aerial parts and were free of the pathogen within 3 It of inoculation. Salmonella persisted in stumps of the plants throughout the observation, irrespective of age of the plants at the time of inoculation. The study revealed the persistence and the phytopathogenic potential of Salmonella on cowpea.