Evaluation of three groups of plant growth-promoting extremophilic rhizospheric bacteria on induction of salinity and alkalinity tolerance in GN۱۵ almond (Prunus amygdalus L.) rootstocks

The use of indigenous extremophilic bacteria with plant growth-promoting haloalkaliphilic properties will help to cope with biotic and abiotic stresses. The present study focused to investigate the effect of these bacteria to induce salinity resistance in almond rootstocks under soil salinity and alkalinity and compare it with non-stress conditions. The roots of ۱۰۸ Garnem rootstocks in four different soils (۲, ۴, ۸, and ۱۶ dS m-۱) were inoculated with two bacterial strains and sterilized control from three groups of halophilic, alkaliphilic, and haloalkaliphilic isolated from the rhizosphere of almond’s cultivation sites. Plant growth-promoting properties, including tri-indole acetic acid production, phosphate mineral dissolution, and exo-polysaccharide production, were measured for alkaliphilic isolates (۲۱۳.۳۳, ۱۲۷.۵۵, and ۵۷۸.۱۱ mg L-۱), haloalkaliphilic isolates (۷۷.۱۳, ۷۳.۹۹, and ۲۸۴.۵۴ mg L-۱), and halophilic isolates (۱۵.۹۸, ۴۰.۱۹ and ۳۵.۹۰ mg L-۱, respectively). The inoculated plants with halophilic bacteria were found to better grow compared to other inoculated plants. In addition, these plants accumulated more chlorophyll, sugar, and proline. The root fresh and dry weights were maximum by the haloalkaliphilic bacteria inoculation. The alkaliphilic and halophilic bacteria also caused a higher increase in fresh and dry weights of shoots. As well, root and shoot moisture contents were the highest ones in the ۱۶ and ۸ dS m-۱ salinity by haloalkaliphilic inoculation. In general, the application of haloalkaliphilic bacteria was found to have a better effect on root growth and halophilic bacteria in the morphological and physiological properties of almond rootstocks. Compared with ۸ dS m-۱ and other salinity levels, extremophile bacteria had a stronger effect on soil salinity and alkalinity mitigation for almond rootstocks at ۱۶ dS m-۱ salinity.

کلیدواژه ها:

Exo-polysaccharide ، Haloalkaliphilic bacteria ، Prolin ، Root-to-shoot ratio ، Strain ، Tri-indole acetic acid. ، Exo-polysaccharide ، Haloalkaliphilic bacteria ، Prolin ، Root-to-shoot ratio ، Strain ، Tri-indole acetic acid