Alleviation of soil salinity on physiological and agronomic traits of rice cultivars using Arbuscular mycorrhizal fungi and Pseudomonas strains under field conditions

Rice cultivation in Iran has a special place and its cultivation area is about 640,000 ha. Soil salinization is one of the most factor in reducing of grain yields and cultivation of paddy rice. Currently, half of Iran's cultivated lands (9.5 million ha) are affected by salinity, which has a major impact on crop yields. For this purpose, an field experiment conducted with the use of microorganisms (Pseudomonas putida strain S34, Pseudomonas fluorescens strain R167, Arbuscular mycorrhizal fungi (AMF) (Rhizophagus irregularis), co-inoculation of P.putida + P.fluorescens + AMF, and a non-inoculated treatment as control) on two rice cultivars (Hashemi and Gilane) in saline and normal soil in north of Iran during the 2018 and 2019. The results showed interactions of microorganisms and soil condition could alleviate the adverse effects of salinity by decreasing H2O2 (14-71% in normal soil and 44-281% in saline soil) and increasing catalase (CAT) activity (39.5-65% in Gilane and 45-61% in Hashemi), proline (17-46% in Gilane and 13.5-52% in Hashemi) and nitrogen (N) concentrations (12-27% in normal soil and 7-23% in saline soil) of leaves. Also microorganisms significantly increased tiller, panicle and grain number plant(-1), and biological and grain yield (23-44.5% and 32.5-56% in normal and saline soil, respectively). Furthermore, the greatest mitigating effects were observed in treated by P.putida + P.fluorescens + AMF plants. This study indicated that P.putida + P.fluorescens + AMF synergistically mitigate harmful impacts of soil salinity in rice cultivars.