Bacterial consortia inoculation mitigates the water shortage and salt stress in an avocado (Persea americana Mill.) nursery

Chile is among the largest avocado producers worldwide; however, currently, its production has diminished mainly attributed to abiotic stresses such as drought and soil salinity. Here, we evaluated the contribution of halotolerant bacterial consortia to water shortage and salt stress tolerance of avocado seedlings ( Persea americana Mill.) under field conditions. Inoculation trials were conducted in a commercial nursery to study the effects of two endophytic (C1 and C2) and two rhizosphere (C3 and C4) halotolerant bacterial consortia on growth, biomass, superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS) of avocado seedlings under salt (2% NaCl) stress and water shortage (50% less irrigation). Ours results revealed that avocado inoculation with C4 significantly ( P ≤ 0.05) increased aerial and root length; aerial and root fresh weight and chlorophyll content of salt-stressed seedlings; and the aerial length and root fresh weight of seedlings under water shortage. Similarly, the C4 significantly ( P ≤ 0.05) increased SOD activity in leaves of both the control and seedlings grown under salt stress and water shortage and also decreased TBARS content in leaves of control plants and of seedlings grown under salt stress. Whereas, C3 increased significantly ( P ≤ 0.05) aerial and root length and root fresh weight of salt-stressed seedlings; and also increased the trunk diameter and chlorophyll content of seedlings under water shortage. Similarly, C3 significantly ( P ≤ 0.05) stimulated SOD activity of leaves as compared to the control seedlings and also reduced the TBARS content of leaves and roots of avocado seedlings under salt stress. In contrast, the endophytic consortia were less efficient than rhizosphere consortia. Thus, C1 only increased the trunk diameter and chlorophyll content of salt–stressed seedlings and C2 increased the chlorophyll content of avocado seedlings under water shortage. Our study showed the favorable effect of bacterial inoculation on avocado nursey in nursery conditions under water shortage and salt stress, and identified consortia that potentially could be used as avocado biofertilizers.