No crops of any kind had previously been grown in the field. Organic manure, rock phosphate and an organic nitrogen fertiliser were added as required according to the results from soil analyses. Raised beds with black plastic mulch were then created and plants of Fern, a day-neutral strawberry cultivar, were grown on them.
The PGPB tested were Bacillus M3 (applied by dipping the plant roots into the bacterial suspension), and Pseudomonas BA-8 and Bacillus OSU-142, which were sprayed onto the foliage. Cultures containing 109 colony-forming units per millilitre of each of the three PGPB were applied separately or in combination.
The PGPB treatments all produced significant increases in cumulative fruit number and total yield, although most other fruit characteristics were unaffected. The highest yield was obtained when a combination of Bacillus M3 and Pseudomonas BA-8 was applied. The PGPB treatments also increased the availability of phosphorous and other elements in the soil.
Effects of Plant Growth Promoting Bacteria on Yield, Growth and Nutrient Contents of Organically Grown Strawberry by Esitken, Yildiz, Ercisli, Donmez, Turan and Gunes (2010). Scientia Horticulturae 124 (1): 62-66. Contents of Scientia Horticulturae and abstracts of papers are provided at www.elsevier.com/locate/scihorti
Dr Ken Cockshull is emeritus fellow at Warwick HRI