Role of Different Additives on Survival of Serratia plymuthica HRO-C48 on Oilseed Rape Seeds and Control of Phoma lingam

For optimum inhibition of plant pathogens, biocontrol agents must be maintained at higher density and survive for a long time in the plant system. Biopriming of seeds with bacteria in the presence of different additives provide a promising technique that might improve the efficacy of biocontrol agents and their application. The aim of this work was to test different additives and stickers on the activity of Serratia plymuthica in oilseed rape in controlling Phoma lingam. Seeds were soaked in bacterial suspensions (log10 11 CFU ml-1) containing one of the following Stickers and additives in a ratio of 1:1:1 (w:v:v): Sodium alginate, Dextran T 40, Polyvinyl alcohol, Methylcellulose, Gum Arabic, Raffinose, Tween 20, and Paraffin oil. Seeds were stored either at room temperature or at 4°C. Number of bacteria inside the seeds was monitored over a period of 12 months. The effect of additives and stickers on bacterial efficacy in controlling Phoma lingam was evaluated in pot experiments. Number of bacterial cells inside the seeds was significantly higher in the seeds coated with GA+MgSO4, RF+MC and PA (log10 7.5 ± 0.2, log10 7.5 ± 0.2 and log10 7.4 ± 0.4, respectively). Interestingly, bacterial concentration in seeds stored at 4°C was higher than that in seeds stored at 20°C. Moreover, after storage for 8 months, Serratia plymuthica was able to control the black leg disease. Our results showed that some additives and stickers prolonged the shelf life of bacteria inside the seeds and improved the efficacy of bacteria in controlling the disease.