Comparison of application methods to prolong the survival of potential biocontrol bacteria on stored sugar-beet seed.
OBJECTIVE
To develop bacterial inoculation treatments on sugar-beet seed that will maintain a commercially acceptable degree of viability for a minimum of 4 months storage at ambient temperature.


RESULTS
Single rifampicin-resistant (Rif(+)) strains of both Gram-positive and negative bacterial isolates (mostly pseudomonads) were applied in turn to sugar-beet seed in a comparative study by seed soaking, encapsulation in alginate, pelleting using an inoculated peat carrier or seed priming. The treated seed was assessed for bacterial survival over a time course by plating out homogenized samples onto a selective medium. Priming inoculation offered a significant improvement over all the other application strategies tested. After pelleting with fungicides and drying at 40 degrees C, Pseudomonas marginalis/putida P1W1 maintained populations of >6.6 log(10) CFU g(-1) seed during 4 months storage at 15 degrees C. Subsequent experiments verified a stabilized population under these storage conditions with commercial pellets at <7% moisture content.


CONCLUSIONS
An inoculation method was established which allowed the survival on seed of a Gram-negative bacterium at ambient temperature with little loss in viability.


CONCLUSIONS
This has promising implications for the delivery of beneficial bacteria, especially Gram-negative strains, on sugar beet.
Walker
R
R
Broom's Barn Research Station, Higham, Bury St Edmunds, Suffolk, UK. r.walker@germains.com
Rossall
S
S
Asher
M J C
MJ
D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D027461:Beta vulgaris / Q000382:microbiology*; D015169:Colony Count, Microbial; D004352:Drug Resistance, Microbial; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005659:Fungicides, Industrial / Q000494:pharmacology; D010572:Pest Control, Biological / Q000379:methods*; D018517:Plant Roots / Q000382:microbiology; D011549:Pseudomonas / Q000187:drug effects / Q000502:physiology; D016958:Pseudomonas putida / Q000187:drug effects / Q000502:physiology; D012231:Rhizobium / Q000187:drug effects / Q000502:physiology; D012293:Rifampin; D012639:Seeds / Q000382:microbiology
D005659:Fungicides, Industrial; D012293:Rifampin