The present work aimed to investigate changes in growth and some metabolic activities in salt-treated Oryza sativa plants by salt irrigation (100 mM) and assessing the role of presoaking of seeds by polyamine putrescine (4.0 mM) with soil treating by cyanobacteria (23 mg/pot) interaction to alleviate these changes. At 70-day old both putrescine and cyanobacteria had a clear effect on the fresh weight plants stressed by salt compared to the control, and the same result was also observed on the dry weight of stressed and unstressed rice plants with salt. Chl (a) and (b) were stimulated especially with the application of a high concentration of putrescine. However, carotenoids were slightly suppressive. The effect of cyanobacteria alone or interacted with putrescine in a significant increase in the photosynthesis activity compared to the control of stressed and non-saline-stressed rice plants at 70-day old.
The total carbohydrate and protein contents of the roots showed a significant increase. A decrease in proline content was observed in both shoots and roots under the influence of cyanobacteria and putrescine overlapped together in saline-stressed plants compared to the control.
The influence of cyanobacteria and putrescine together show a significant effect on nitrogen, phosphorus, potassium, magnesium, iron, and manganese shoot contents compared to the control. Exogenous application of putrescine and cyanobacteria succeeded in mitigating the harmful effect of salt on growth rate and various physiological metabolites.