The aim of this study was to characterize fluorescent pseudomonads isolates of dryland wheat for salinity and drought tolerance and plant growth-promoting (PGP) traits in the presence or absence of salinity (4% NaCl) and evaluate the effect of two effective strains, Pseudomonas helmanticensis B30 and P. baetica B21, on phosphorus (P) uptake by wheat plant grown in a saline calcareous soil fertilized with rock phosphate (RP) and triple superphosphate (TSP) under water-deficit stress (55% of field capacity (FC) and 88% FC). All fluorescent pseudomonads isolates had the ability to grow at different drought stress levels and at salinity level of 4% NaCl. In addition, a significant percentage of these isolates retained their ability to produce PGP traits (especially P solubilization and indole-3-acetic acid production) in the presence of salinity. The results showed that 80% FC moisture level compared to 55% FC moisture level significantly increased plant growth indices and P uptake by wheat plant. In most of the measured parameters, RP treatment (8 mg P kg−1 soil) alone did not show any significant difference compared to negative control (without RP and TSP), but combination treatments with RP and TSP at all levels (3, 6, and 9 mg P kg−1 soil) increased these parameters compared to negative control. In non-stress and water-deficit stress conditions, bacterial strains significantly increased soil available P, growth indices (a 41.6% increase in root dry weight and an 11% increase in shoot dry weight), grain yield (a 17% increase), shoot P uptake of wheat plant as compared to control (without bacterial strains). Overall, the results of this study showed that dryland wheat rhizosphere harbors drought- and salinity-tolerant phosphate-solubilizing fluorescent pseudomonads isolates with potential of producing PGP traits in the presence or absence of salinity and improving P uptake by the plant under water-deficit stress.

中文翻译：

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缺水胁迫下根际荧光假单胞菌菌株改善小麦植物（Triticum aestivum L.）对磷的吸收

本研究的目的是表征旱地小麦荧光假单胞菌分离株在盐度（4% NaCl）存在或不存在下的盐度和耐旱性以及植物生长促进 (PGP) 特性，并评估两种有效菌株假单胞菌的效果helmanticensis B30 和 P. baetica B21，在缺水胁迫（田间持水量的 55%）下，在用磷矿 (RP) 和三重过磷酸钙 (TSP) 施肥的盐渍钙质土壤中生长的小麦植物对磷 (P) 的吸收和 88% FC）。所有荧光假单胞菌分离物都具有在不同干旱胁迫水平和 4% NaCl 盐度水平下生长的能力。此外，这些分离株中有很大一部分在盐度存在的情况下保留了它们产生 PGP 特性的能力（特别是 P 溶解和 indole-3-乙酸生产）。结果表明，80% FC 水分含量与 55% FC 水分含量相比显着提高了小麦植物的植物生长指数和磷吸收。在大多数测量参数中，与阴性对照（没有 RP 和 TSP）相比，单独的 RP 处理（8 mg P kg-1 土壤）没有显示出任何显着差异，但在所有水平（3, 6和 9 mg P kg-1 土壤）与阴性对照相比增加了这些参数。在非胁迫和缺水胁迫条件下，菌株显着增加了土壤有效磷、生长指数（根干重增加 41.6%，地上部干重增加 11%）、谷物产量（增加 17%）、与对照（无细菌菌株）相比，小麦植物的芽磷吸收。全面的，