Characterization of Plant Growth Promoting Rhizobial Isolates for Pigeon Pea (Cajanus cajan [L.] Millsp)

Abstract

Study was conducted to isolate and characterize Rhizobia from root nodules of pigeon pea from Vijayapur, Kalaburgi and Bagalkot districts of northern regions of Karnataka. Ten Rhizobial isolates and reference strain PPM35B were subjected for nodulation test. All the isolates showed positive result for nodulation. The number of nodules was ranging from 12 to 14.5 per plant. All these isolates were also subjected for functional characterization. The amount of IAA, GA production and ACC deaminase activity by different rhizobial isolates ranged from 16.60 to 22.85 g IAA/ ml of broth, 11.00 to 14.43 g/25ml of broth and 44.5 to 73.5 nmoles of α-ketobutyrate/mg/h of broth respectively. The diameter of P, Zn and Si solubilization by the rhizobial isolates was ranged from 4.5 to 10.3 mm, 9.5 to 20.5 mm and 5.5 to 6.5 mm, respectively. These isolates were further subjected for morphological and biochemical characterization. All the isolates were found to be rod shaped and gram negative. All the isolates were positive for citrate utilization, catalase, urease, oxidase, acid and gas production tests whereas negative for Voges proskauer’s and indole production test.