Abstract

Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth by a wide variety of mechanisms. The use of PGPR is steadily increasing in agriculture and offers an attractive way to replace chemical fertilizers and pesticides. Here, we have isolated and characterized PGPR traits from the rhizosphere soil of pigeon pea and tested for the growth enhancement of pigeon pea. Rhizosphere soils were collected from different areas of Samalkot, Pithapuram, Peddapuram and Kakinada in India. A total of 65 isolates have been identified and characterized for their morphological, cultural, staining and biochemical characteristics, of which 35 isolates have been selected for further screening of PGPR traits. Sixteen isolates were successfully characterized for the PGPR traits like indole acetic acid (IAA) production, phosphorus solubilization and 1-aminocyclopropane-1-carboxylate (ACC)deaminase. Among the sixteen isolates, seven were found to be high IAA producing. Six were found to be efficient phosphate solubilizers, two were shown to be promising in both IAA production, phosphate solubilization and mineralizing capacity. These isolates showed growth promotion in pigeon pea for seedling emergence, increase of shoot length, root length, dry matter production, nodule number and nodule mass. Furthermore, PGPR isolates remarkably increased seed germination of pigeon pea. The two promising isolates were identified for 16sRNA sequencing and found to be Bacillus cereus andEnterobacter cancerogens.

Key words: Indole acetic acid (IAA), plant growth promoting rhizobacteria (PGPR), phosphorus solubilization, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), seed germination.