Co-inoculation of Achromobacter xylosoxidans and Pseudomonas fluorescens 5B1 to enhance the growth and nutrient uptake of two varieties of Solanum tuberosum

Water shortages limit potato (Solanum tuberosum L.) production in drought-prone areas, underscoring the need for low-input solutions to enhance crop drought resistance. Plant growth-promoting rhizobacteria (PGPR) are an environmentally friendly and promising solution. In this study, Achromobacter xylosoxidans and Pseudomonas fluorescens strain 5B1 were isolated and identified using microscopical, cultural, biochemical, and molecular techniques by 16S rRNA sequencing. A. xylosoxidans and P. fluorescens were assessed for their ability alone and in combination to increase drought resistance, growth, and nutrient uptake of Harry and Sefra potato under drought stress in Erbil Governorate, Kurdistan Region, Iraq. The results showed that Co-inoculation with (Achromobacter xylosoxidans and Pseudomonas fluorescens strain 5B1) bacteria had the highest effect on potato growth and nutrient uptake (plant length 47cm, root length 65.33cm, 30.33 tubers, weight of tuber 850g, carbohydrates 1.67 %, protein 31.75%, carotene 2.98% and total chlorophyll 0.422% ), while the lowest effect was recorded by Achromobacter xylosoxidans (plant length 34cm, root length 49.33cm, 23.33 tubers, weight of tuber 490.66g, carbohydrates 1.088%, protein 14.60%, carotene 2.47% and total chlorophyll 0.279%) and Pseudomonas fluorescens (plant length 39cm, root length 54.33cm, 26.33 tubers weight of tuber 644.66g, carbohydrates 1.6268%, protein 19.69%, carotene 2.65% and total chlorophyll 0.396%) compare to controlled treatment (untreated) that is (plant length 53.33 cm, root length 65.33cm, 27.66 tubers, weight of tuber 866.66g, carbohydrates 1.944%, protein 35.13%, carotene 2.66% and total chlorophyll 0.478%) . Depending on the above results, it can be concluded that Pseudomonas fluorescens5B1 and Achromobacter xylosoxidans. It can be used as a biofertilizer to enhance plant growth and nutrient uptake, instituting a more sustainable approach to chemical fertilizers.