Pre-colonized seedlings with arbuscular mycorrhizal fungi: an alternative for the cultivation of Jatropha curcas L. in salinized soils

The aim of this study was to test the hypothesis that Jatropha curcas L. seedlings previously inoculated with arbuscular mycorrhizal fungi (AMF) in non-salinized soil and later transplanted to salinized soil are more tolerant to saline stress. The experiment was conducted in greenhouse using a randomized block design in a 4 x 2 factorial scheme. The first factor consisted of salinized soil with electrical conductivity (EC) of 2, 5, 8 and 10 dS/m, and the second consisted of non-colonized plants, and plants that were pre-colonized with AMF, with eight replicates. Salt had a deleterious effect on plants non-inoculated with AMF, which showed reduced growth and photosynthetic activity and increased stress indicators, such as lipid peroxidation, proline accumulation, and high antioxidant enzymatic activity. On the other hand, pre-colonized plants were less affected by the presence of salt in the soil. Seedlings pr-einoculated with AMF presented the same growth rate and photosynthetic activity in all saline treatments. No increase in lipid peroxidation and antioxidant enzymatic activity was observed in seedlings pre-inoculated with AMF even under high saline concentration of 10 dS/m EC. The results suggest the existence of a mechanism to mitigate the effects of saline stress on pre-colonized seedlings. Therefore, pre-colonized J. curcas seedlings are an alternative for the cultivation of this species in salinized soils.