Mitigation of effect of salt stress on the nodulation, nitrogen fixation and growth of chickpea (Cicer arietinum L.) by triple microbial inoculation

Abstract

Plant-associated microorganisms play a critical role in agricultural productivity. Symbiotic microorganisms interact with each other and allow their host leguminous plants to maintain optimal nutrient levels and enhance their growth. Therefore, the goal of the current study was to investigate the synergistic interaction of different symbiotic microbes and its beneficial effect on the nodulation, nodule efficiency, and growth of salt-affected chickpea plants (Cicer arietinum L.). Rhizobium sp. (MK358859) was isolated from the root nodules of chickpea plants. In vitro, magnetite nanoparticles (Fe3O4-NPs) at a concentration of 150 μg/ml significantly enhanced the growth ofRhizobium compared with bulk FeCl3. The impact of seven soil salinity levels (0, 25, 50, 75, 100, 150, and 200 mM NaCl) on germination and subsequent growth was measured. The salinity levels ranging from 25 to 150 mM significantly inhibited the growth of chickpea plants, while the 200 mM level hindered their germination. The influence of triple microbial inoculation of chickpea plants grown in soil with 0, 75 and 150 mM NaCl was studied. Inoculation with mycorrhizal fungi, Fe3O4 NP-inducedRhizobium, and endophytic Stenotrophomonas maltophilia significantly improved the nodulation, leghaemoglobin content, nitrogenase activity, and growth of chickpea grown at salinity level of 75 and 150 mM compared with the controls. The mitigation of the destructive effect of salinity stress was due to improvement in the nutritional status of plants as determined by their K, P, carbohydrate and protein contents. Such triple microbial inoculation could be a successful bio-fertilizer that can contribute to protecting chickpea plants from salinity by attenuating salt-induced oxidative damage.