Influence of Seedling Age on the Susceptibility of Tomato Plants to Ralstonia solanacearum during Protray Screening and at Transplanting

Pious  Thomas; Reshmi  Upreti

doi:10.4236/ajps.2014.512190

Pious Thomas^*, Reshmi Upreti

Abstract: The study was undertaken to assess whether seedling age played any role in governing the vulnerability of tomato to the bacterial wilt pathogen, Ralstonia solanacearum, based on the preliminary observations that the extent of mortality during seedling-stage screening was relatively less in older seedlings. Employing the virulent strain ‘NH-Av01’ isolated from tomato, 2-, 3-, 4- or 5-week-old seedlings of susceptible ‘Arka Vikas’ raised in organic cocopeat in 98 cavity protrays were inoculated with the pathogen through root-injury inoculation approach. Disease symptoms appeared earlier and with more severity in 2-week-old seedlings followed by 3-, 4- and 5-week-old saplings recording 74%, 68%, 63% and 49% mortality, respectively, after four weeks of inoculation suggesting that older the seedlings, less the susceptibility to the pathogen. The growth characteristics of seedlings (shoot height, shoot and root weights) showed a significant increase with seedling age (0.21, 0.54, 1.14 and 2.09 g gross weight/seedling at 2, 3, 4 and 5 weeks, respectively) indicating healthier saplings with delay in inoculation time. In subsequent trials, seedlings of 3, 4, 5 or 6 weeks were transplanted to field-sick soil in protrays or in pots with monitoring for 1 - 4 months which indicated a significant reduction in disease incidence and severity with increase in seedling age. The observations suggested that seedling age should be considered as a major factor influencing the susceptibility of tomato seedlings to R. solanacearum with the chances of variations in the extent of disease incidence or inconsistent results during seedling-stage screening and the possibility of escapes with older seedlings. Two-week seedlings formed the best when the aim is to induce maximum disease incidence, while transplanting at 5 - 6 weeks stage appeared the best when the objective is minimal disease incidence or formulating disease management strategies.

Keywords: Bacterial Wilt, Disease Resistance, Screening Methodology, Seedling Vigor, Solanum lycopersicum, Tomato Breeding

Cite this paper: Thomas, P. and Upreti, R. (2014) Influence of Seedling Age on the Susceptibility of Tomato Plants to Ralstonia solanacearum during Protray Screening and at Transplanting. American Journal of Plant Sciences, 5, 1755-1762. doi: 10.4236/ajps.2014.512190.

References

[1] Hayward, A.C. (1991) Biology and Epidemiology of Bacterial Wilt Caused by Pseudomonas solanacearum. Annual Review of Phytopathology, 29, 65-87.
http://dx.doi.org/10.1146/annurev.py.29.090191.000433

[2] Genin, S. and Denny, T.P. (2012) Pathogenomics of the Ralstonia solanacearum Species Complex. Annual Review of Phytopathology, 50, 67-89.
http://dx.doi.org/10.1146/annurev-phyto-081211-173000

[3] Jyothi, H.K., Santhosha H.M. and Basamma (2012) Recent Advances in Breeding for Bacterial Wilt (Ralstonia solanacearum) Resistance in Tomato—Review. Current Biotica, 6, 370-398.

[4] Ji, P., Momol, M.T., Rich, J.R., Olson, S.M. and Jones, J.B. (2007) Development of an Integrated Approach for Managing Bacterial Wilt and Root-Knot on Tomato under Field Conditions. Plant Disease, 91, 1321-1326.
http://dx.doi.org/10.1094/PDIS-91-10-1321

[5] Vanitha, S.C., Niranjana, S.R., Mortensen, C. N. and Umesha, S. (2009) Bacterial Wilt of Tomato in Karnataka and Its Management by Pseudomonas fluorescens. BioControl, 54, 685-695.
http://dx.doi.org/10.1007/s10526-009-9217-x

[6] Ramesh, R. and Phadke, G.S. (2012) Rhizosphere and Endophytic Bacteria for the Suppression of Eggplant Wilt Caused by Ralstonia solanacearum. Crop Protection, 37, 35-41.
http://dx.doi.org/10.1016/j.cropro.2012.02.008

[7] Thomas, P., Sadashiva, A.T., Upreti, R. and Mujawar, M.M. (2014) Direct Delivery of Inoculum to Shoot Tissue Interferes with Genotypic Resistance to Ralstonia solanacearum in Tomato Seedlings. Journal of Phytopathology, In Press.

[8] Kelman, A. (1954) The Relationship of Pathogenicity of Pseudomonas solanacearum to Colony Appearance in a Tetrazolium Medium. Phytopathology, 44, 693-695.

[9] Elphinstone, J.G., Hennessey, J., Wilson, J.K. and Stead, D.E. (1996) Sensitivity of Different Methods for the Detection of Ralstonia solanacearum in Potato Tuber Extracts. EPPO Bulletin, 26, 663-678.
http://dx.doi.org/10.1111/j.1365-2338.1996.tb01511.x

[10] Thomas, P., Mujawar, M.M., Sekhar, A.C. and Upreti, R. (2014) Physical Impaction Injury Effects on Bacterial Cells during Spread-Plating Influenced by Cell Characteristics of the Organisms. Journal of Applied Microbiology, 116, 911-922.
http://dx.doi.org/10.1111/jam.12412

[11] Mew, T.W. and Ho, W.C. (1977) Effect of Soil Temperature on Resistance of Tomato Cultivars to Bacterial Wilt. Phytopathology, 67, 909-911.
http://dx.doi.org/10.1094/Phyto-67-909