Enhancing Salinity Tolerance in Triticale via Synergistic Effect of Plant Growth Promoting Bacteria and Arbuscular Mycorrhizal Fungi

Background: Soil salinity is a major abiotic stress factor that severely limits crop productivity worldwide threatening the sustainability of modern agriculture. This study investigated the combined application of plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) in mitigating salt stress in triticale (×Triticosecale). Methods: Three salinity levels (0, 100 and 200 mM NaCl) and nine microbial treatments including two PGPB strains (KF58B Brevibacterium frigoritolerans and KF63C Paenibacillus xylanilyticus) and two AMF species (Glomus etunicatum and Funneliformis mosseae) were tested using under controlled conditions. Glutathione peroxidase (GSH), catalase (CAT) and malondialdehyde (MDA) alterations were investigated to observe plant stress responses. Result: Salinity had a significant inhibitory effect on plant growth. Average seedling fresh weight decreased from 0.759 g (control) to 0.393 g under 200 mM NaCl, while root fresh weight dropped from 0.687 g to 0.167 g. Root length declined by 48.2%, from 29.81 cm to 15.44 cm. Enzymatic activities and stress indicators showed notable variations. According to salinity x treatment interaction, the highest CAT (32.77 ng mL-1) and GSH (5.12 ng mL-1) activity were observed in the KF63C + F. mosseae and KF58B + F. mosseae under severe salinity, respectively. MDA reached a peak of 4.81 ng mL-1 under 200 mM NaCl conditions, but, it reduced by 74.6% with KF58B+G. etunicatum combination. Although no statistically significant differences were detected in morphological characteristics at the seedling stage, enzymatic observations indicated stress mitigation in plants. These findings supported the potential of co-inoculation with PGPB (Brevibacterium frigoritolerans and Paenibacillus xylanilyticus) and AMF (G. etunicatum and F. mosseae) on improving salt stress tolerance in triticale during early seedling stage. In paticular, combination of B. frigoritolerans and F. mosseae is recommended to mitigation of salinity stress in triticale during early seedling stage.