Abstract:
Plant Growth Promoting Microorganisms (PGPMs) are beneficial organisms found in the plant eco-systems and enhance plant growth. Their ability to solubilize the unavailable soil phosphorus, increase the uptake of nitrogen and synthesize growth promoting hormones such as auxins puts them in a good position to be utilized as bio-fertilizers. It has been documented that the rice plant rhizosphere is a habitat for various microorganisms which act as bio-fertilizers. It has been reported that inoculation of rice plants with these microbes resulted in increased plant growth. The present study was undertaken to assess the effectiveness of selected microorganism isolates as rice seedling promoters under field conditions. Prior to inoculation, the microbial isolates had been screened for their physiological properties as PGPMs. To investigate the effects of PGPMs inoculants on the growth of Basmati 317 rice plants, field experiments were conducted at Jomo Kenyatta University of Agriculture and Technology in the period 2013 to 2014. The experimental design was split-plot with four replications. Data was collected on growth attribute parameters including plant height, root length, tiller numbers, shoot dry weight and root dry weight. Analysis of variance procedure for split-plot design was done, and the Duncan multiple range test was used for separating the treatment means. The main-plots (concentrations) as well as the sub-plots (inoculants) treatments were significantly different at p<0.005 in all the parameters tested. Interaction between concentrations and inoculants was only found in the root length. Plants inoculated with Bacillus, Enterobacter, Staphylococcus, Brevudimonas, Pseudomonas, Trichoderma, Penicillium, Aspergillus and mixed bacteria performed better than the uninoculated plants whereas best results were obtained with plants applied with chemical fertilizers. From the results, we can conclude that the use of these PGPMs as inoculant bio-fertilizers is therefore beneficial for rice production since they enhanced the growth of rice plants.
