Response of two tomato cultivars differing in salt tolerance to inoculation with mycorrhizal fungi under salt stress

Abstract 

Effects of arbuscular mycorrhizal fungi (AMF) and salt stress on nutrient acquisition and growth of two tomato cultivars exhibiting differences in salt tolerance were investigated. Plants were grown in a sterilized, low-P (silty clay) soil-sand mix. Salt was applied at saturation extract (EC_e) values of 1.4 (control), 4.9 (medium) and 7.1 dS m^–1 (high salt stress). Mycorrhizal colonization occurred irrespective of salt stress in both cultivars, but AMF colonization was higher under control than under saline soil conditions. The salt-tolerant cultivar Pello showed higher mycorrhizal colonization than the salt-sensitive cultivar Marriha. Shoot dry matter (DM) yield and leaf area were higher in mycorrhizal than nonmycorrhizal plants of both cultivars. Shoot DM and leaf area but not root DM were higher in Pello than Marriha. The enhancement in shoot DM due to AMF inoculation was 22% and 21% under control, 31% and 58% under medium, and 18% and 59% under high salinity for Pello and Marriha, respectively. For both cultivars, the contents of P, K, Zn, Cu, and Fe were higher in mycorrhizal than nonmycorrhizal plants under control and medium saline soil conditions. The enhancement in P, K, Zn, Cu, and Fe acquisition due to AMF inoculation was more pronounced in Marriha than in the Pello cultivar under saline conditions. The results suggest that Marriha benefited more from AMF colonization than Pello under saline soil conditions, despite the fact that Pello roots were highly infected with the AMF. Thus, it appears that Marriha is more dependent on AMF symbiosis than Pello.