The Potential of Using a Fungal–Bacterial Biofilmed Biofertilizer for Upland Cereals

A common constraint in growing coarse-grained cereals and upland rice in the dry zone of Sri Lanka is the inability of farmers to supply adequate plant nutrients to these crops, owing to poverty, high cost of chemical fertilizers, and the risk and uncertainty affiliated with such crops. A biofilmed biofertilizer (BFBF) developed for rice at the Institute of Fundamental Studies (IFS) contains soil microorganisms such as N2 fixing bacteria, fungi and cyanobacteria to improve the soil properties through the symbiotic relationships among these microorganisms. This has been tested as a biofertilizer for lowland rice production with very promising results. Present study was carried out to test the suitability of the BFBF, which was originally developed for lowland rice, as a biofertilizer for upland rice (BG 300) and two other cereals, finger millet and common millet, grown in the dry zone of Sri Lanka. The effect of the BFBF on germination and seedling growth of the three crops was studied in a plant house. Plant growth promoting effect with BFBF was also evaluated. Using a dry zone soil in pots, the crops were treated with BFBF + 50% of chemical fertilizers (CF) recommended by the Department of Agriculture, and 100% CF alone. BFBF was applied as a seed treatment and a soil surface spray and then a foliar spray. Two and half months after sowing, plants were harvested and biological nitrogen fixation (nitrogenase activity through acetylene reduction assay), and shoot and root dry weights were determined. All BFBF inoculated crops were found to have root hairs colonized by biofilms with significant plant growth promoting effects. The germination percentages over the controls increased significantly by ca. 74% and 14% for finger millet and rice, respectively. Rice and finger millet also showed positive responses to acetylene reduction assay. Results showed that the BFBF developed for rice are also beneficial for finger millet, which implies that the tested BFBF is not crop specific. However, crop-specific BFBFs should be developed for some crops, like common millet.