Root Colonization vs. Seedling Growth, in Two Azospirillum-Inoculated Wheat Species

Abstract

Data evaluating the growth promoting effects of Azospirillum on wheat seedlings according to the inoculum level/root colonization effectiveness (number of bacterial cells), is scarce. Uniform 1-cm size, 72-h old wheat seedlings grown in the dark at 22 °C were inoculated with: i) 103, 105, 107 and 108A. brasilense cells per T. aestivum cv. ProINTA Federal seedling; ii) 102, 105 and 108A. brasilense cells per T. durum cv. Buck Topacio seedling; iii) 106 heat killed bacteria (HKB) cells per cultivar seedling; iv) phosphate buffer pH 6.8 (NI) as control seedlings for both cultivars. Afterwards, seedling growth proceeded in water in the dark at 22 °C for another 48 h. Alive or dead Azospirillum cells were suspended in phosphate buffer pH 6.8. Root and shoot growth were determined measuring the length and projected area of their digitalized images. When treated with inocula concentrations ranging from 102 to 105 cells per seedling, both Triticum species reached a maximum level of colonization harboring 106 to 107 cells per seedling. No differences could be detected between NI and HKB treated seedlings for both Triticum species. Triticum aestivum cv. ProINTA Federal seedlings reached the maximum growth promotion when roots were colonized with a number of bacterial cells ranging from 5 · 106 to 1.5 · 108 per seedling. Triticum durum cv. Buck Topacio seedlings showed maximum growth promotion when 3.3 · 107 cells were present in their roots. Higher values of colonization showed no growth promoting effects with respect to the controls. It may be concluded that in these experimental conditions the optimum inoculum concentration is 5 · 105 cells per seedling for both T. aestivum cv. ProINTA Federal and T. durum cv. Buck Topacio.

References

  1. Alvarez, M.I., Sueldo, R.J., Barassi, C.A. 1996. Effect of Azospirillum on coleoptile growth in wheat seedlings under water stress. Cereal Res. Comm. 24:101–107.

    Google Scholar 

  2. Arunakumari, A., Lamm, R.B., Neyra-Estens, C.A. 1992. Changes in cell surface properties of azospirilla in relation to cell pleomorphism and aggregation. Symbiosis 13:291–305.

    Google Scholar 

  3. Bashan, Y. 1993. Potential use of Azospirillum as biofertilizer. Turrialba 43:286–291.

    Google Scholar 

  4. Bashan, Y., Holguin, G., de-Bashan, L.E. 2004. Azospirillum -plant relationships: physiological, molecular, agricultural, and environmental advances (1997–2003). Can. J. Microbiol. 50:521–577.

    CAS  Article  Google Scholar 

  5. Casanovas, E.M., Barassi, C.A., Sueldo, R.J. 2002. Azospirillum inoculation mitigates water stress effects in maize seedlings. Cereal Res. Comm. 30:343–350.

    Google Scholar 

  6. Casanovas, E.M., Barassi, C.A., Andrade, F., Sueldo, R.J. 2003. Azospirillum -inoculated maize plant responses to irrigation restraints imposed during flowering. Cereal Res. Comm. 31:395–402.

    Google Scholar 

  7. Chen, C., Bauske, E.M., Musson, G., Rodríguez-Cabaña, R., Kloepper, J. 1995. Biological control of Fusarium on cotton by use of endophytic bacteria. Biol. Control 5:83–91.

    Article  Google Scholar 

  8. Creus, C.M., Sueldo, R.J., Barassi, C.A. 1997. Shoot growth and water status in Azospirillum -inoculated wheat seedlings grown under osmotic and salt stresses. Plant Physiol. Biochem. 35:939–944.

    CAS  Google Scholar 

  9. Creus, C.M., Sueldo, R.J., Barassi, C.A. 1998. Water relations in Azospirillum -inoculated wheat seedlings under osmotic stress. Can. J. Bot. 76:238–244.

    Google Scholar 

  10. Creus, C.M., Sueldo, R.J., Barassi, C.A. 2004. Water relations and yield in Azospirillum -inoculated wheat exposed to drought in the field. Can. J. Bot. 82:273–281.

    Article  Google Scholar 

  11. De Troch, P., Vanderleyden, J. 1996. Surface properties and motility of Rhizobium and Azospirillum in relation to plant root attachment. Microb. Ecol. 32:149–169.

    Article  Google Scholar 

  12. Dobbelaere, S., Croonenborghs, A., Thys, A., Vande Broek, A., Vanderleyden, J. 1999. Phytostimulatory effect of Azospirillum brasilense wild type and mutant strains altered in IAA production in wheat. Plant Soil 212:155–164.

    CAS  Article  Google Scholar 

  13. Dufrêne, I.F., Vermeiren, H., Vanderleyden, J., Rouxhet, P.G. 1996. Direct evidence for the involvement of extracellular proteins in the adhesion of Azospirillum brasilense. Microbiology 142:855–865.

    Article  Google Scholar 

  14. Gan, Y., Stobbe, E.H., Moes, J. 1992. Relative date of wheat seedling emergence and its impact on grain yield. Crop Sci. 32:1275–1281.

    Article  Google Scholar 

  15. Guddanti, S., Chambers, J.L. 1993. GSRoot, Version 5.00. Automated Root Length Measurement Program. Users Manual. Lousiana State University, Agricultural Center.

  16. Hallmann, J., Quadt-Hallmann, A., Mahaffee, W.F., Kloepper, J.W. 1997. Bacterial endophytes in agricultural crops. Can. J. Microbiol. 43:895–914.

    CAS  Article  Google Scholar 

  17. Jacoud, C., Faure, D., Wadoux, P., Bally, R. 1998. Development of a strain-specific probe to follow inoculated Azospirillum lipoferum CRT1 under field conditions and enhancement of maize root development by inoculation. FEMS Microbiol Ecol. 27:43–51.

    CAS  Article  Google Scholar 

  18. Okon, Y., Itzigsohn, R. 1995. The development of Azospirillum as commercial inoculant for improving crop yields. Biotech. Adv. 13:415–424.

    CAS  Article  Google Scholar 

  19. Okon, Y., Labandera-González, C.A. 1994. Agronomic applications of Azospirillum brasilense: an evaluation of 20 years worldwide field inoculation. Soil Biol. Biochem. 26:1591–1601.

    CAS  Article  Google Scholar 

  20. Postgate, J.R. 1969. Viable counts and viability. In: Norris, J.R., Ribbons, E.W. (eds), Methods in Microbiology. Academic Press, New York, pp. 611–628.

    Google Scholar 

  21. SAS Institute, 2000. The SAS OnlineDoc system for Windows. Release 8.2. SAS Institue Inc., Cary, New Carolina.

    Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to C. A. Barassi.

Rights and permissions

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Cite this article

Pereyra, M.A., González, R.L., Creus, C.M. et al. Root Colonization vs. Seedling Growth, in Two Azospirillum-Inoculated Wheat Species. CEREAL RESEARCH COMMUNICATIONS 35, 1621–1629 (2007). https://doi.org/10.1556/CRC.35.2007.4.9

Download citation

Keywords

  • Azospirillum colonization
  • wheat
  • seedling growth
  • growth promotion