The effect of a suspension of the strain Pseudomonas sp. GEOT18 on growth and productivity of spring barley with additional application of phosphorus fertilizers

The purpose of the current work was to study the effect of a suspension of the strain Pseudomonas sp. GEOT18 on growth and productivity of spring barley variety Sonet with application of phosphorus fertilizers in the Non-Blackearth Zone of Russia (using the Vologda Region as an example). The study was conducted during the vegetation periods of 2020–2024, at the same time in 2023–2024 the study included examining the effect of the strain suspension on barley plants with additional application of phosphorus fertilizer. The study was conducted at the experimental plots of the Vologda Research Center of the Russian Academy of Sciences (Vologda Oblast, Non-Blackearth Zone of Russia). During the study, bacteria were introduced twice, by pre-sowing seed soaking and by spraying the phyllospheres with a working solution of the suspension during the tillering stage. The working solution of the studied strain was obtained by diluting the suspension (cell density 10 9 CFU/ml) with tap water at a ratio of 1:20. Tap water was used as a control. Superphosphate was used as a phosphorus fertilizer at doses of 25, 50, and 100 g/m². The study has demonstrated the growthpromoting effect of the suspension of the strain Pseudomonas sp. GEOT18 with an increase in the assimilatory surface area, photosynthetic pigment content in leaves, and weight parameters of the experimental barley varieties compared to the control. While application of phosphorus fertilizers significantly increased barley growth parameters, the crop achieved even greater results when both phosphorus fertilizer and the suspension of the studied strain were applied simultaneously. Grain productivity from the suspension of Pseudomonas sp. GEOT18 alone exceeded the control by 16– 40%, depending on seasonal conditions. Phosphorus fertilizers increased barley grain yield per area unit by 48–100%, and their combined use with the suspension of the studied strain by 72–109% (5–12% increase relative to variants with the exclusive use of phosphates), depending on the conditions of the season and the dosage of fertilizer application.