The investigation of Pseudomonas bacteria on some morpho-physiological traits of two cultivars of potatoes (Solanum tuberosum L.) with different irrigation intervals

The use of biological fertilizers can be effective and beneficial in abiotic environmental stresses specially in drought stress, arid and semi-arid regions of the world.

An experiment was conducted to investigate the effect of deficit irrigation stress and Pseudomonas bacteria on some morpho-physiological traits of two potato cultivars at the research farm of Shahroud University of Technology located in Bastam region in 2010. Treatments included irrigation cycles as the main factor at three levels (7, 10, and 14-days), Pseudomonas bacteria (inoculation and non-inoculation) and cultivar at two levels (Savalan and Agria) as the sub-factor with three replications.

The results showed that the highest dry matter accumulation in the aerial part was observed in the 7-day irrigation cycle and inoculation with Pseudomonas bacteria. The number of tubers was increased about 12.66% because of inoculation with Pseudomonas fluorescens per square meter. Savalan cultivar interaction and 7-day irrigation cycle also obtained the highest number of tubers with an average of 166.39 per square meter. The application of inoculation with Pseudomonas fluorescens increased chlorophyll A by 9.3%. It compared with non-bacterial inoculation. Chlorophyll B had the highest chlorophyll content in the main treatments of the 7-day irrigation cycle and Agria cultivar. The highest amount of potassium content was obtained at the rate of 2.06% at the highest irrigation cycle (14-day). The application of inoculation and non-inoculation with Pseudomonas caused the highest amount of proline at 14-day irrigation cycle. Inoculation with Pseudomonas bacteria increased the final tuber yield about 22.85%. Furthermore, Savalan cultivar increased the final tuber yield about 110.09% in the 7-day irrigation cycle compared to the 14-day. Finally, the 7-day irrigation cycle was the best irrigation cycle to increase the morpho-physiological traits, chlorophyll, number of tubers, and the final tuber yield. Inoculation with Pseudomonas bacteria increased the effectiveness of these traits. Also, the production of compatible osmolytes (proline and potassium) improved drought stress tolerance in 14-day irrigation cycle. Growth-promoting bacteria improves seed germination, root propagation, shoot and root weight, leaf area, chlorophyll content, hydraulic conductivity, protein, nutrient absorption and plant yield (Batool et al., 2020). Growth-promoting bacteria of polysaccharides increases biomass production under drought stress conditions (Daffonchio et al., 2015). Potassium is one of the most important osmolytes under drought stress conditions and adverse conditions (Anschütz et al. 2014). Cellular and physiological responses are carried out through organic salts as proline to reduce cellular damage during drought stress. It is an osmotic regulator (Merwad et al., 2018)

The 7-day irrigation cycle was the best irrigation cycle to increase the morpho-physiological traits, chlorophyll, number of tubers, and the final tuber yield. Inoculation with Pseudomonas bacteria increased the effectiveness of these traits. Also, the production of compatible osmolytes (proline and potassium) improved drought stress tolerance in 14-day irrigation cycle.