Effect of different strains of Pseudomonas bacteria on physiological traits and yield components of potato (Solanum tuberosum L.) under drought stress conditions

In order to investigate the effects of different Pseudomonas bacterial strains, including fluorescens, Chloraphis and Putida strains, on the morpho-physiological characteristics and performance of Sante variety potato under drought stress in the Jiroft region, an experimental study was conducted in the form of a split-plot design with a randomized complete block design with three replications for two years, 2019–2020 and 2020–2021. The main factor of the experiment consisted of three levels of drought stress (40, 65, and 90 mm of evaporation from the evaporation class A pan), while the sub-factor included four levels of Pseudomonas bacterial strains (control, strain T12 (Pseudomonas fluorescens RO7), strain T13 (Pseudomonas putida RO3) and strain T17 (Pseudomonas chlororaphis RO1). The results showed that the applied drought stress treatments had no effect on the chlorophyll a content. The use of Pseudomonas bacteria strains increased the content of chlorophyll b and total chlorophyll (a+b). The carotenoid content of leaves at 90 evaporation from the Class A pan with the application of bacteria strain T17 showed the lowest amount compared to the treatment without bacteria and strains T12 and T13. Application of bacteria strain T13 showed the highest superoxide dismutase (SOD) enzyme activity at different drought stress levels. There was no significant difference in peroxidase enzyme activity between different Pseudomonas bacterial strains and the treatment without bacterial application at various drought stress levels. The highest catalase enzyme activity in the leaves was observed in the application of Pseudomonas bacterial strains T12 and T17. The application of Pseudomonas bacterial strains led to a significant increase in shoot dry weight, tuber dry weight, and total tuber weight in potato plants compared to the treatment without bacterial application at all drought stress levels.