الفهرس 
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Abstract
Two laboratory and field experiments were conducted at 2021 and 2022 growing seasons. A Laboratory experiments were carried out at soil, Water, and Environment Research Institute (SWERI), Agriculture Research Center (ARC), Giza, Egypt and agronomy seed laboratory department of agronomy Faculty of Agriculture Ain shams university, Cairo Egypt. Field experiments were carried out at Ismailia Agricultural Research Station, Ismailia Governorate.
1. Laboratory experiments:
Using the plant extracts of Mentha viridis and Nutrient agar medium (NA) as media for growth of plant growth promoting rhizobactria.
Experiment included the following factors:
1.1. Bacterial strains
Bacillus subtilis (BSR-8), Pseudomonas fluorescens (PSR-11), and Bradyrhizobium japonicum, used in this study, were kindly given by the Soil, Water, and Environment Research Institute (SWERI), Agriculture Research Center (ARC), Giza, Egypt.
1.2. Media used for microbial cultivation:
Nutrient agar medium (NA) and mentha-based culture medium.
• In- Laboratory screening the production of indole acetic acid (IAA), gibberellins (GA), carbohydrate and phosphorus solubilization on both plant-based culture media and synthetic media.
• Compare between the growth of microbial isolates in both natural and synthetic media.
1.3. The obtained results can be summarized in the following:
1.3.1. The three strains appeared their ability to successfully solubilize inorganic phosphate, showing a greater potency with P. fluorescens.
1.3.2. P. fluorescens followed by B. subtilis was higher than B. japonicum in the production of IAA, and total carbohydrates While, B. subtilis showed the maximum levels on gibberellic acid production.
1.3.3 Bacterial strains produce high amount of IAA, GA3 and phosphorus solubilization on Mentha-based culture medium. While produce high amount of carbohydrates on synthetic medium.
1.3.4 The economic study of the medium showed that the cost of natural liquid media is drastically less than the synthetic liquid media where the cost of 100 liter liquid natural medium is 100 Egyptian pounds (LE) or less and 600 LE for synthetic medium.
2. Field experiments:
Two field experiments were carried out during the two summer seasons of 2021 and 2022 at Ismailia Agricultural Research Station, Ismailia Governorate Egypt, to study the effects of Plant Growth –Promoting Rhizobacteria as bio fertilizers on growth, yield and quality of two soybean (Glycine max L.) cultivars.
Experiment included the following factors:
2.1. Bio- fertilizers treatments:
• Control
• Inoculation with Bacillus subtilis
• Inoculation with Pseudomonas fluorescens
• CO- Inoculation with Bacillus and Pseudomonas
2.2 Soybean cultivars:
• Giza 111
• Giza 21
2.3. The results obtained can be summarized as follows:
2.3.1. Growth; root and physiological traits after 60 and 90 days from sowing:
2.3.1.1. Effect of bio-fertilizers treatments on growth; root and physiological traits after 60 and 90 days from sowing:
The mixture (Bacillus and Pseudomonas) possessed higher values of plant height, number of leaves plant-1; number of branches plant-1; dry stem weight plant-1; dry leaves weight plant-1; number of pods plant-1; Root length, Root dry weight; Number of root nodules plant-1; Root nodules dry weight; CO2; chlorophyll (A) ;chlorophyll (B) and carotenoids compared to other treatments in both seasons.
2.3.1.2. Effect of soybean cultivars on growth; root and physiological traits after 60and 90 days from sowing:
Giza111cultivar showed maximum growth parameter for all vegetative growth traits and root traits except plant height compared to the Giza 21 cultivar at 60 and 90 days from sowing during both seasons.
2.3.1.2. The interaction between soybean cultivars and bio-fertilization:
Giza111cultivar was traits with co- inoculation (Bacillus and Pseudomonas) exhibited the maximum values of growth parameter for all vegetative growth traits and root traits except plant height. While Giza 21cultivar was traits with co- inoculation (Bacillus and Pseudomonas) recorded the highest value in plant height, exceeded the control by 24.2% & 27.8% and 25.4% & 46.4% in 2021 & 2022 seasons at 60 and 90 days from sowing respectively.
2.3.2. Yield and yield attributes traits:
2.3.2.1. Effect of bio-fertilizers treatments on yield and yield attributes traits:
Statistically significant results recorded in co- inoculation (Bacillus and Pseudomonas) treatment increased the plant height by 7.9% & 7.01%, number of branches plant-1, by 19.3% & 24.54% ; number of pods plant-1 by 54.9%&41.5% ; 100 seeds weight by 22.1% & 29.7% ; biological yield by 18.15% & 26.01% ; seeds yield by30.4% &33.9 ; & 6.52 % ; Protein content in seeds by 14.9% & 15.5% and Nitrogen content in seeds by 14.9% &15.5% compared with control in 2021 & 2022 seasons respectively.
2.3.2.2. Effect of soybean cultivars on yield and yield attributes traits:
The assessed yield traits showed considerable variations between soybean cultivars, Giza-111 significantly outperformed Giza-21 in number of branches plant-1 by 11.77% &6.68%; Number of pods plant-1 by 8.18%, 6.3%;100 seeds weight by 5.3% and 6.5; Seeds yield by8.9% &8.6; number of seeds pod-1 by 3.6% and 7.14, While Giza 21 outperformed Giza-111 in plant height by0.8% and 0.75% in both seasons respectively.
2.3.2.3. Effect of interaction between bio-fertilizers treatments and soybean cultivars on yield and yield attributes traits:
Giza111cultivar was traits with co- inoculation (Bacillus and Pseudomonas) exhibited the maximum values of number of branches plant-1; number of pods plant-1; 100 seeds weight; biological yield; seeds yield. While Giza 21cultivar was traits with co- inoculation (Bacillus and Pseudomonas) recorded the highest value in plant height.
2.3.3. Chemical traits
2.3.3.1 Effects of bio-fertilizers treatments on chemical traits of two soybean cultivars:
CO- inoculation (P. fluorescens and B. subtilis) increased the seeds oil content by 6.46 % & 6.52 % and Protein content in seeds by 14.9% & 15.5% compared with control in 2021 and 2022 seasons respectively.
2.3.3.2 Effect of soybean cultivars on chemical traits
Giza-111 significantly outperformed Giza-21 in seeds oil content by 2.49% & 2.76% and phosphorus content in seeds by 6.5%, 4.3%in both season respectively.
While Cultivars, Giza-21 recorded the highest value in Protein content in seeds by 4.17% and 3.5% and Nitrogen content in seeds by 4.13%, 3.56% in both seasons respectively.
2.3.3.3 Effect of interaction between bio-fertilizers treatments and soybean cultivars on chemical traits
Treating Giza-111 and Giza-21 cultivars with co-inoculation (P. fluorescens and B. subtilis) was the most efficient interaction treatment for enhancing seeds oil content; Protein content; phosphorus content in seeds and Nitrogen content in seeds in both seasons.
Conclusion
Results cleared that Bacterial strains developed on natural medium (mint) which is able to produce multiple PGP activities like IAA, GA production, carbohydrate and solubilize the phosphate may improve the growth of plants. On comparison the production of plant growth-promoting substances on both natural and synthetic medium the natural medium gave better results and the alternative media was found to be highly cost effectively. According this results field experiment was carried out to study the effect of bio-fertilizer that resulted from laboratory experiment on growth and productivity of soybean under sandy soil conditions.
The present field study demonstrated a significant positive effect of Bacillus, Pseudomonas, and Co-inoculation (Bacillus and Pseudomonas), on growth parameters, yield and its components of two soybean cultivars .Where, Co- inoculation of (Bacillus subtilis and Pseudomonas fluorescens) showed higher vegetative growth, yield components, yield, and quality. Giza111 cultivar was traits with (Bacillus and Pseudomonas) must be taken into account for its high productivity.
Thus, according to this data Co-inoculation of (Bacillus and Pseudomonas) investigation as a good example of plant growth promoting rhizobacteria to increase the yield and quality of soybean plants with Giza 111 cv. of soybean