Abstract
Background and aims
Inoculation of legumes at sowing with rhizobia has arguably been one of the most cost-effective practices in modern agriculture. Critical aspects of inoculant quality are rhizobial counts at manufacture/registration and shelf (product) life.
Methods
In order to re-evaluate the Australian standards for peat-based inoculants, we assessed numbers of rhizobia (rhizobial counts) and presence of contaminants in 1,234 individual packets of peat–based inoculants from 13 different inoculant groups that were either freshly manufactured or had been stored at 4 °C for up to 38 months to determine (a) rates of decline of rhizobial populations, and (b) effects of presence of contaminants on rhizobial populations. We also assessed effects of inoculant age on survival of the rhizobia during and immediately after inoculation of polyethylene beads.
Results
Rhizobial populations in the peat inoculants at manufacture and decline rates varied substantially amongst the 13 inoculant groups. The most stable were Sinorhizobium, Bradyrhizobium and Mesorhizobium with Rhizobium, particularly R. leguminosarum bv. trifolii the least stable. The presence of contaminants at the 10−6 level of dilution, i.e. >log 6.7 g−1 peat, reduced rhizobial numbers in the stored inoculants by an average of 37 %. Survival on beads following inoculation improved 2–3 fold with increasing age of inoculant.
Conclusions
We concluded that the Australian standards for peat-based rhizobial inoculants should be reassessed to account for the large differences amongst the groups in counts at manufacture and survival rates during storage. Key recommendations are to increase expiry counts from log 8.0 to log 8.7 rhizobia g−1 peat and to have four levels of inoculant shelf life ranging from 12 months to 3 years.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Albareda M, Rodriguez-Navarro DN, Comacho M, Temprano FJ (2008) Alternatives to peat as a carrier for rhizobia inoculants: solid and liquid formulations. Soil Biol Biochem 40:2771–2779
Biederbeck VO, Geissler HJ (1993) Effect of storage temperatures on Rhizobium meliloti survival in peat- and clay-based inoculants. Can J Plant Sci 73:101–110
Brockwell J (1980) Experiments with crop and pasture legumes—principles and practice. In: Bergersen FJ (ed) Methods for evaluating biological nitrogen fixation. Wiley, Chichester, pp 417–488
Bullard GK, Roughley RJ, Pulsford DJ (2005) The legume inoculant industry and inoculant quality control in Australia: 1953–2003. Aust J Exp Agric 45:127–140
Bushby HVA, Marshall KC (1977) Some factors affecting the survival of root nodule bacteria on dessication. Soil Biol Biochem 9:143–147
Catroux G (1991) Inoculant quality standards and controls in France. In: Thompson JA (ed) Report on the expert consultation on legume inoculant production and quality control. FAO, Rome, pp 113–120
Catroux G, Hartmann A, Revellin C (2001) Trends in rhizobial inoculant production and use. Plant Soil 230:21–30
Date RA, Roughley RJ (1977) Preparation of legume inoculants. In: Hardy RWF, Gibson AH (eds) A treatise on dinitrogen fixation. Wiley, Chichester, pp 243–276
Deaker R, Roughley RJ, Kennedy IR (2004) Legume seed inoculation technology—a review. Soil Biol Biochem 36:1275–1288
Gemell LG, Hartley E, Herridge DF (2005) Point-of-sale evaluation of preinoculated and custom-inoculated pasture legume seed. Aust J Exp Agric 45:161–169
Hartley E, Gemell LG, Slattery JF, Howieson JG, Herridge DF (2005) Age of peat-based lupin and chickpea inoculants in relation to quality and efficacy. Aust J Exp Agric 45:183–188
Hartley EJ, Gemell LG, Deaker R (2012) Some factors that contribute to poor survival of rhizobia on preinoculated legume seed. Crop Pasture Sci 63:858–865
Herridge DF (2008) Inoculation technology for legumes. In: Dilworth MJ, James EK, Sprent JI, Newtown WE (eds) Nitrogen-fixing leguminous symbioses. Springer, Dordrecht, pp 77–105
Herridge DF, Peoples MB, Boddey RM (2008) Global inputs of biological nitrogen fixation in agricultural systems. Plant Soil 311:1–18
Hiltbold AE, Thurlow DL, Skipper HD (1980) Evaluation of commercial soybean inoculants by various techniques. Agron J 72:675–681
Hume DJ, Blair DH (1992) Effect of numbers of Bradyrhizobium japonicum applied in commercial inoculants on soybean yield in Ontario. Can J Microbiol 38:588–593
Hungria M, Louro MF, Mendes IC, Campo RJ, Graham PH (2005) Inoculant preparation, production and application. In: Werner D, Newton WE (eds) Nitrogen fixation in agriculture, forestry, ecology, and the environment. Springer, Dordrecht, pp 223–253
Lupwayi NZ, Olsen PE, Sande ES, Keyser HH, Collins MM, Singleton PW, Rice WA (2000) Inoculant quality and its evaluation. Field Crop Res 65:259–270
Materon LA, Weaver RW (1985) Inoculant maturity influences survival of rhizobia on seed. Appl Environ Microbiol 49:465–467
Maurice S, Beauclair P, Giraud J, Sommer G, Hartmann A, Catroux G (2001) Survival and change in physiological state of Bradyrhizobium japonicum in soybean (Glycine max L. Merril) liquid inoculants after long-term storage. World J Microbiol Biotechnol 17:635–643
Olsen PE, Rice WA, Bordeleau LM, Biederbeck VO (1994) Analysis and regulation of legume inoculants in Canada: the need for an increase in standards. Plant Soil 161:127–134
Patrick HN, Lowther WL (1995) Influence of the number of rhizobia on the nodulation and establishment of Trifolium ambiguum. Soil Biol Biochem 27:717–720
Revellin C, Meunier G, Giraud JJ, Sommer G, Wadoux P, Catroux G (2000) Changes in the physiological and agricultural characteristics of peat-based Bradyrhizobium japonicum inoculants after long-term storage. Appl Microbiol Biotechnol 54:206–221
Rodriguez-Navarro DN, Temprano F, Orive R (1991) Survival of Rhizobium sp. (Hedysarum coronarium L.) on peat-based inoculants and inoculated seed. Soil Biol Biochem 23:375–379
Roughley RJ (1982) The storage, quality control and use of legume seed inoculants. In: Graham PH, Harris SC (eds) Biological nitrogen fixation technology for tropical agriculture. CIAT, Colombia, pp 115–126
Roughley RJ, Vincent JM (1967) Growth and survival of Rhizobium spp. in peat culture. J Appl Bacteriol 30:362–376
Roughley RJ, Gemell LG, Thompson JA, Brockwell J (1993) The number of Bradyrhizobium sp. (Lupinus) applied to seed and its effect on rhizosphere colonization, nodulation and yield of lupin. Soil Biol Biochem 25:1453–1458
Roughley RJ, Simanungkalit RDM, Gemell LG, Hartley EJ, Cain P (1995) Growth and survival of root-nodule bacteria in legume inoculants stored at high temperatures. Soil Biol Biochem 27:707–712
Singleton P, Keyser H, Sande E (2002) Development and evaluation of liquid inoculants. In: Herridge D (ed) Inoculants and nitrogen fixation of legumes in Vietnam, ACIAR Proceeding 109e, Brisbane, Australia, pp 52–66
Stephens JHG, Rask HM (2000) Inoculant production and formulation. Field Crop Res 65:249–258
Thompson JA (1991) Report on the expert consultation on legume inoculant production and quality control. FAO, Rome, 145 pp
Willems A (2006) The taxonomy of rhizobia: an overview. Plant Soil 287:3–14
Acknowledgments
We acknowledge the financial and operational support of the NSW Department of Primary Industries and the Grains Research & Development Corporation (GRDC) of Australia.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible Editor: Euan K. James.
Rights and permissions
About this article
Cite this article
Herridge, D.F., Hartley, E. & Gemell, L.G. Rhizobial counts in peat inoculants vary amongst legume inoculant groups at manufacture and with storage: implications for quality standards. Plant Soil 380, 327–336 (2014). https://doi.org/10.1007/s11104-014-2087-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11104-014-2087-8