DEEPTI KHATRI, ANJALA DURGAPAL*, PRASOON K. JOSHI AND AMIT PANDE
Defence Institute of Bio-Energy Research, Goraparao, P. O. Arjunpur, Haldwani-263 139, Nainital
(Uttarakhand), India
*(e-mail : anjala.69@gmail.com; Mobile : 9412991777)
(Received : October 15, 2019; Accepted : December 10, 2019)
ABSTRACT
Plant growth promoting rhizobacteria (PGPR) are a group of beneficial bacteria that actively colonize rhizosphere and plant roots, besides enhancing plant growth. Phosphate-solubilizing and N-fixing bacteria
were isolated from rhizospheric soil and root nodules of horsegram [Macrotyloma uniflorum (Lam.) Verdc.]. Isolated bacteria were screened for their efficiency. Solubilization of phosphate in broth was highest with strain D5 (2012), whereas D55 demonstrated the highest nitrogenase activity, response to indole acetic acid and siderophore production. The isolates D55 (2012) and D55 were identified as Bacillus and Rhizobium,
respectively, using biochemical and molecular methods. Seeds of horsegram were subjected to four different treatments. Under pot conditions, the treatments were : (i) seeds inoculated with Rhizobium (T1), (ii) seeds inoculated with Bacillus and soil supplemented with 50 g of tri-calcium phosphate per pot (T2), (iii) seeds inoculated with Bacillus (T3) and (iv) control (T4). Treatments T1, T2 and T3 significantly improved growth, yield, chlorophyll content, total protein content of seeds and nutrient uptake by plants, over the control. The seed yield increased by 105.39, 73.33 and 76.47% in T1, T2 and T3, respectively, over the control. Compared with the control, in treated plants, maturation period in horsegram was shortened by 15 days, which suggested that rhizobacteria could be used as potent bio-fertilizers. Treatment of seeds and soil with Rhizobium culture proved better than that with Bacillus.
Key words : IAA, horsegram, N-fixing bacteria, nitrogenase, PGPR, PSB