Abstract

Salinity stress severely affects growth, nodulation and yield of chickpea (Cicer arietinum L.). However, inoculation with Mesorhizobium strains containing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase improves the plant growth by reducing the level of ethylene induced by salt stress. Fifty (50) Mesorhizobium isolates were obtained from nodules of chickpea plants on yeast extract mannitol agar (YEMA) medium. Mesorhizobium isolates were screened for ACC utilization and growth at different salt concentrations in YEMA medium. Six salt tolerant Mesorhizobium isolates were checked for their role in plant growth promotion under pot house conditions in chillum jar assembly. Mesorhizobium strains having ACC utilization ability caused an increase in the nodule number, nodule weight and shoot dry weight after plant growth for 50 and 80 days, both with and without NaCl. Mesorhizobium isolate MBD26 showed 294 mg/plant shoot dry weight without salt condition after 50 days of plant growth. Mesorhizobium isolate MBD26 increased shoot dry weight by 49.52% (without salt) and 41.53% in the presence of salt (40 mM NaCl) after 80 days of plant growth. It was observed that inoculation with Mesorhizobium isolates containing ACC-deaminase improved nodulation and plant growth of chickpea over ACC deaminase lacking isolates. Thus, inoculation with Mesorhizobium strains possessing ACC utilization ability could be a sustainable approach to improve plant growth under salinity stress.

Key words: 1-Aminocyclopropane-1-carboxylic acid (ACC) utilization, salt stress, Mesorhizobium, chickpea, nodulation, plant growth.