Effect of plant growth-promoting rhizobacterial composite culture on the growth of chickpea seedlings

Abstract

In the present study, 20 soil and plant samples from 13 villages of Raipur, Durg, and Balod District of Chhattisgarh (India) were collected from chickpea fields. From these samples, a total of 86 isolates including 16 Rhizobium, 40 Azotobacter, 29 Azosprillum, and one PSB were obtained on selective culture media. All the isolates were screened for their plant growth-promoting traits. Three (GmR8, ASL3 & ASL4) out of 86 were finally selected for further studies. One Azotobacter isolate, i.e., Azo137, was selected from the departmental culture collection. Finally, four isolates including GmR8 (Rhizobium), ASL3, ASL4 (Azospirillum), and Azo137 were selected for composite culture formulations. GmR and ASL4 were siderophore-producing isolates, whereas ASL3 and Azo137 were IAA producer along with their ability to fix nitrogen. Five composite cultures were prepared randomly and tested for effect on the growth of chickpea (the seedling test and the pot experiment). Among all the composite culture groups, C2 (GmR8, Azo137, ASL4) significantly increased the root (10.84 cm) and shoot (8.10 cm) length, whereas biomass (3.60 g) was the highest in the case of C1 (GmR8, Azo137, ASL3, ASL4) of seedlings as compared to the control (6.80 cm, 2.60 cm, and 3.30 g, respectively). Overall, the study revealed a better performance of composite or mixed culture over individual bacteria.