Growth and Carbohydrate Compositions of Three Gossypium Species Inoculated with Rhizophagus intraradices under Salinity Stress

Expansion of salt stress in cultivable fields prevents plant physiological functions and reduces crop yield. Arbuscular Mycorrhizal Fungi (AMF), as a bio-amelioration of salt stress, protects cellular osmosis via disaccharide and polysaccharide metabolism changes. In this study, three Gossypium species (i.e., G. hirsutum, G. barbadense, and G. herbaceum) colonized with Rhizophagus intraradices [with AMF and without AMF] were cultivated under saline irrigation treatments (ECe 4 Ds m-1= S0, 8-9= S1, and 12-13= S2) as a factorial experiment. Salinity treatments were initiated at flowering. Generally, according to physiological traits, [+AMF] colonized with G. barbadense was more tolerant in exposure to 12-13 dS m-1 salinity, while G. hirsutum with [+AMF] was just tolerant until 8-9 dS m-1. This is because, the highest and the least leaf area were observed in G. barbadense [+AMF] under 8-9 and 12-13 dS m-1, respectively. In 12-13 dS m-1, the highest root volume, root dry weight, seed weight, and fiber weight were obtained in G. barbadense [+AMF]. Moreover, the highest sugar content in root and leaves and the highest starch content of root, leaves, and seed cotyledon were observed in G. barbadense [+AMF] under 12-13 dS m-1 treatment. Under 8-9 dS.m-1 salinity, the highest starch, Sucrose Phosphate Synthase (SPS) and Sucrose Phosphatase (SP) enzyme activities were in roots of G. barbadense [+AMF]. The present study suggests that despite dramatic physiological alterations under high-salinity in comparison with mild-salinity, AMF and G. barbadense showed the best symbiotic performance under 12-13 dS m-1.