Amelioration of salt stress in chickpea (Cicer arietinum L.) by coinculation of ACC deaminase-containing rhizospheric bacteria with Mesorhizobium strains

Abstract

Chickpea is a major legume crop grown in the semi-arid tropics and its yields are adversely affected by salinity. In this study, 55 rhizobacterial isolates obtained from the chickpea rhizosphere soil were screened for their salt tolerance. At 3% NaCl concentration, 41.8% rhizobacterial isolates formed colonies varying from 0.5-10 mm size and only 10.9 per cent isolates showed growth at 4% NaCl concentration. Significant growth on ACC supplemented medium plates was observed in 32.7% rhizobacterial isolates. Coinoculation studies with ACC+ as well as ACC- Mesorhizobium and rhizobacterial isolates were made on chickpea under chillum jar conditions containing sloger’s broth with salt (EC, 4dS/m) and without salt. Coinoculation of Mesorhizobium isolate MBD26 (ACC+) and rhizobacterial isolate RHD18 (ACC+) formed 59 nodules/plant and caused 112.9% increase in plant dry weight as compared to uninoculated control plants at 50 days of plant growth, whereas in the presence of salt, only 31.2% increase in plant dry weight was observed in comparison to uninoculated plants. At 80 days of plant growth, coinoculation of Mesorhizobium isolate MBD26 (ACC+) with rhizobacterial isolate RHD18 (ACC+) further increased the nodule number (78 nodules/plant) and 141.9% increase in shoot dry weight was observed as compared to uninoculated plants. Thus, it was concluded that coinoculation of ACC+ Mesorhizobium and rhizobacterial isolates showed more stimulatory effect on nodulation and plant biomass under normal and salt amended treatments.