effects of arbuscular mycorrhizal fungus and plant growth promoting rhizobacteria (pgpr) under drought stress on growth of ornamental osteospermum (osteospermum hybrida ‘passion mix’)

effects of arbuscular mycorrhizal fungus (glomus mossea ca) and plant growth promoting rhizobacteria (pgpr) of bacillus pantea and psedomonas putida were evaluated on growth parameters of osteospermum (osteospermum hybrida ‘passion mix’) under different watering conditions (field capacity, two and one third of field capacity). arbuscular mycorrhizal fungus (amf) and pgpr were applied as single or mixed. a factorial trial based on randomized complete block design with 3 replications per treatment and 4 replicates was carried out under greenhouse conditions. root colonization, growth parameters and p concentration in plant was measured. results showed that pgpr and mycorrhizal inoculated plants had better nutritional conditions than that of non-inoculated plants. moreover, there was a synergetic effect between amf and pgpr in this study. pgpr were as much effective as amf on alleviating the negative impacts of drought stress. according to the results, applied microorganisms were more effective on improving the growth parameters at 70% of field capacity, while at 40% of field capacity; their effective role was reduced, although the plants were persistent, yet. results revealed exploitation of amf and pgpr and administering an optimized irrigation regime can be effective on improving yield of this plant.