Evaluation of rhizosphere, rhizoplane and phyllosphere bacteria and fungi isolated from rice in Kenya for plant growth promoters

Rice (Oryza sativa L.) is the most important staple food crop in many developing countries, and is ranked third in Kenya after maize and wheat. Continuous cropping without replenishing soil nutrients is a major problem in Kenya resulting to declining soil fertility. The use of chemical fertilizers to avert the problem of low soil fertility is currently limited due to rising costs and environmental concerns. Many soil micro-organisms are able to solubilize the unavailable phosphorus, increase uptake of nitrogen and also synthesize growth promoting hormones including auxin. The aim of this study was to isolate and characterize phyllosphere, rhizoplane and rhizosphere micro-organisms from Kenyan rice with growth promoting habits. In this study whole plant rice samples were collected from different rice growing regions of Kenya. 76.2%, over 80% and 38.5% of the bacterial isolates were positive for phosphate solubilization, nitrogenase activity and IAA production whereas 17.5% and 5% of the fungal isolates were positive for phosphate solubilization and IAA production respectively. Hence these micro-organisms have potential for utilization as bio-fertilizers in rice production.