Increased tolerance of Mexican lime (Citrus aurantifolia Swingle) seedlings to salinity stress when inoculated with endophytes spergillus nigerA and Bacillus aquimaris extracted from seaweed

Endophytes play an important role in protecting plants. In this study, endophytic combination of Aspergillus niger and Bacillus aquimaris OD14 was used to improve tolerance of Mexican lime seedlings to salinity stress. Three months after inoculation, salinity stress of 0, 2000, 4000 and 6000 μs/cm was applied. After 8 weeks, morphological, biochemical and elements adsorption traits of seedlings were evaluated. The experiment was carried out as factorial in a completely randomized design with three replications. The results showed that in 6000 μs/cm water salinity, endophytic compound increased stem length (103.64%), trunk diameter (103.04%), number of leaves (444.41%) and root length and width (232.02% and 41.63% respectively). Endophyte increased 76.29% of SPAD chlorophyll content compared to control. Also, the uptake of root potassium (34.95%) and shoot calcium (115.15%) increased and the uptake of sodium elements was decreased (29.49%) compared to control. Endophytic combination could significantly reduce ion leakage (65.57%) and increase proline content (69.3%) in inoculated seedlings compared to control. In general, marine endophytes can be used as a suitable option to increase plant tolerance to salinity.