Inoculation of plant growth promoting bacteria and arbuscular mycorrhizal fungi improve chickpea performance under water deficit conditions

Abstract Chickpea (Cicer arietinum L.) currently ranks second in the world's production of grain legumes and it is considered a cheap source of plant-based protein. In Mediterranean regions, predicted changes in climate are likely to further worsen drought stress and increase the economic vulnerability of chickpea production. Plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) have the potential to improve plant growth and ameliorate the adverse effects of drought stress. The aim of this study was to assess the effects of inoculation with PGPB (Mesorhizobium sp., Burkholderia sp. and Pseudomonas sp.) and AMF (Rhizophagus irregularis, Funneliformis geosporum and Claroideoglomus claroideum) on the growth, grain yield and protein content of chickpea in a field experiment under different irrigation regimes throughout the growing season (100% water requirements (WR), 50% WR, 25% WR, 100% WR only during reproductive stages, and rainfed). Based on two years of results, the beneficial effects of co-inoculation (PGPB+AMF) on plant growth parameters of chickpea allow a cumulative grain yield of about 13,838 kg ha−1, resulting in an increase of 6% when as compared to a single inoculation and 24% over the non-inoculated plants. Plants inoculated with PGPB+AMF, and irrigated only during the reproductive stages, had the highest cumulative grain yield (18,157 kg ha−1), resulting in an increase of 16% and 237% over fully irrigated plants inoculated with PGPB+AMF and non-inoculated plants under rainfed conditions, respectively. In water-scarce environments, deficit irrigation only during the reproductive stage allows farmers to achieve higher yields with less water consumption, which, when combined with microbial inoculation, has the potential to benefit agricultural production of chickpea.