Abstract

Arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) have been proposed as biofertilizers for sustainable agriculture. Nevertheless, many of the delivery approaches for these beneficial microorganisms have the disadvantage of limited applicability. The study aim was to evaluate the fertilizing potential of seed coating with microbial fertilizers on growth and yield parameters of maize and sorghum. Field trials were conducted using a seed coating technique where AMF spores (Rhizophagus fasciculatus and Rhizophagus aggregatus) and PGPR (Leifsonia sp.) were applied around the seeds of maize (Early-Thai) and sorghum (Nganda). Experiments included the following treatments: Coated seed, coated seed in combination with mineral fertilizer (NPK, 15-15-15) at 75 kg/ha, uncoated seed without fertilizer and NPK fertilizer applied at 150 kg/ha. Data were collected on root AMF colonization, plant growth, yield parameters and soil AMF spore richness and density. Research in this area suggests that there is little likelihood of a significant response from seed coating, despite high root AMF colonization rates. However, plants treated with microbial fertilizer in combination with 50% NPK fertilizer achieved significantly higher final heights and yields for both maize and sorghum. Plant production achieved reached that of NPK fertilizer at 150 kg/ha, suggesting that in our case of poor soils, the application of microbial fertilizer alone is not sufficient to achieve significant improvements in plant production. We also found that neither microbial fertilizer, nor mineral treatments had any effect on spore morphotype richness. However, seed coating further increased the spore density.

Key words: Zea mays, Sorghum bicolor, seed coating, arbuscular mycorrhizal fungal, plant growth promoting rhizobacteria, fertilizers, growth and yield, field trial.