Relative efficacy of Pseudomonas spp., containing ACC-deaminase for improving growth and yield of maize (Zea mays L.) in the presence of organic fertilizer

This study was designed to assess the performance of plant growth promoting rhizobacteria (PGPR) containing ACC-deaminase for improving growth and yield of maize in the presence of organic fertilizer. Organic fertilizer was prepared by composting fruit and vegetable wastes in a locally-fabricated unit and enriched with N fertilizer applied @ 147 g kg -1 compost. This ‘organic fertilizer’ was used to formulate bio-fertilizers by using three PGPR strains containing ACC-deaminase, Pseudomonas putida biotype A (Q7), Pseudomonas fluorescens (Q14) and Pseudomonas fluorescens biotype G (N3), separately. The organic- and/or bio-fertilizers were applied to maize @ 300 kg ha -1 without/with 88 kg ha -1 urea-N in the field trials. A basal dose of P and K (100 and 50 kg ha -1 , respectively) was applied to all plots and also tested in the field trials in the absence of organic-/bio-fertilizer. Results of field study revealed that the organic fertilizer supplemented with 88 kg ha -1 N was equally effective to full dose of N-fertilizer (175 kg ha -1 ) in improving cob weight, fresh biomass and grain yield of maize. However, bio-fertilizer supplemented with 88 ha -1 N fertilizer significantly increased the growth and yield of maize over full dose of N-fertilizer and exhibited superiority over organic fertilizer. Organic-/bio-fertilizer application also significantly enhanced N, P and K uptakes. The Pseudomonas fluorescens biotype G (N3) containing biofertilizer was found best to increase grain yield and nutrient uptake both in the presence or absence of 88 kg N ha -1 . Results may imply that organic waste could be composted into value-added soil amendment by enriching/blending it with N and PGPR containing ACC-deaminase activity. This approach is based on using organic- or bio-fertilizers (N-enriched and inoculated compost) at lower rates (just 300 kg ha -1 ) instead of tons ha -1 of non-enriched composts. Moreover, this strategy could also be useful to protect our environments against threat posed by organic wastes.