Effect of plant growth-promoting rhizobacteria inoculation on soil characteristics, nutrients uptake and growth of bell pepper (Capsicum annum L.)

Document Type : Research Paper


1 Department of Horticulturer Science, Faculty of Agriculture, University of Shahrekord, Charmahal-va-Bakhtiari, Iran

2 Soil Science and engineering Department, Faculty of Agricultural, Shahrekord University, Shahrekord, Iran

3 Department university of Sharekord


In order to investigate the effect of growth-promoting bacteria inoculation on soil characteristics, nutrients uptake and growth of bell pepper, a randomized complete block design with five species of growth-promoting bacteria (Bacillus subtilis, Azospirillum lipoferum, Azotobacter chroococcum, Enterobacter cloacae and Pseudomonas putida) with three repetitions was carried out in Isfahan Wheat Field greenhouse in 2021. The chemical and biological properties of the soil, NPK uptake, and the growth and yield characteristics were investigated. The results showed that the addition of growth-promoting bacteria effects on some soil characteristics and bell pepper growth. The treatments showed a significant difference in terms of total nitrogen, phosphorus and potassium available in soil, respiration and rhizospheric microbial population, NK uptake, yield and fruit number (p≤0.01). The best soil nitrogen content (0.44%), nitrogen uptake (28.8 g.m-2) and shoot dry weight (0.565 g.m-2) were observed in Azotobacter chroococcum treatment. The highest rhizospheric microbial population (7.6×106 cfu.g-1) and R/S ratio was 47.9 in Enterobacter cloacae treatment. Fresh weight and dry weight of plant shoot were higher in Azospirillum lipoferum treatment, which was not significantly different from Azotobacter chroococcum and Enterobacter cloacae treatments. In the treatment of Enterobacter cloacae, the yield (18.8 kg.m-2) and the fruits number (65.8/m2) were higher. The application of Enterobacter cloacae, Azotobacter chroococcum and Azospirillum lipoferum bacteria was higher effect on the growth indicators of pepper, which can be recommended for the use of these bacteria as biofertilizers in bell pepper cultivation.


Main Subjects



Plant growth promoting rhizobacteria (PGPR) are associated with plant roots, with metabolism and metabolic processes to increase plant efficacy and augment plant productivity and immunity by reducing fertilizer application rates and nutrient runoff. Studies were conducted to evaluate bell pepper transplants amended with some PGPR isolates in terms of soil characteristics, nutrients uptake and growth.


This research was conducted in a greenhouse in Isfahan, in form of a randomized complete block design with three replications in year 1400. The treatments included five genera of growth stimulating bacteria (Bacillus subtilis, Azospirillum lipoferum, Azotobacter chroococcum, Enterobacter cloacae and Pseudomonas putida) and control treatment without microbial inoculation. Chemical and biological properties of the soil, nitrogen, phosphorus and potassium uptake, and growth and fruit yield characteristics were investigated after harvest.


Results showed that addition of growth-promoting bacteria affects some soil characteristics and bell pepper growth. Treatments showed a significant difference in terms of total nitrogen, available phosphorus and potassium of soil, respiration and microbial population of rhizosphere, nitrogen and potassium uptake, yield and number of fruits (p≤0.01). The best soil nitrogen content (0.44%), nitrogen uptake (28.8 g/m2) and shoot dry weight (0.565 g/m2) were observed in Azotobacter crococcum treatment. Soil basic microbial respiration was higher in Pseudomonas putida treatment (272.4 µg CO2 .g-1.day-1), which showed a significant difference (p≤0.05) with Enterobacter cloacae and control (without inoculation). The highest rhizosphere microbial population and rhizosphere to non-rhizosphere population ratio (R/S) was in Enterobacter cloacae treatment (47.9). The shoot fresh and dry weight of the plant were higher in the Azospirillum treatment, which was not significantly different from the Azotobacter and Enterobacter treatments. Microbial inoculation effect (MIE) in Azospirillum and Azotobacter treatments were higher than the other treatments, which showed a significant difference (p≤0.05) compared to Bacillus subtilis and Pseudomonas treatments. Yield (18.8 kg/m2) and fruits number (65.8/m2) were higher in Enterobacter cloacae treatment.


Results of this study showed that inoculation of plant growth-promoting bacteria has the potential to increase the growth and nutrients uptake of bell pepper and affect biochemical characteristics of cultivated soil. This increase in growth and yield of the plant was positively correlated with the increase in nutrients uptake in plant shoot and to some extent with microbial inoculation effect. The effect of using strains of Enterobacter cloacea, Azotobacter crococcum and Azospirillum lipophrum on growth indicators of bell pepper in greenhouse conditions has been greater than the other strains, which can be recommended as bio-fertilizers in bell pepper cultivation. It is important to evaluate the adaptability of inoculated microorganisms to these culture conditions in order to achieve the maximum benefit from their application. Results of this study can be important in plant healthy and organic production systems.

Keywords: Azotobacter, Enterobacter, Nitrogen uptake, Soil biological properties, Yield.


Ademola, O. & Agele, OS. (2015). Effects of nutrient sources and variety on the growth and yield of three cultivars of pepper (Capsicum annuum L.) in Southwestern Nigeria. New York Science Journal. 8(10):21-29.
Adesemoye, AO. & Egamberdieva, D. (2013). Beneficial effects of plant growth- promoting rhizobacteria on improved crop production: Prospects for Developing Economies. Springer-Verlag Berlin Heidelberg, 45-63.
Akram, NA. & Ashraf, M. (2013). Regulation in plant stress tolerance by a potential plant growth regulator, 5-aminolevulinic acid (ALA). Journal of Plant Growth Regulation, 32, 663–679.
Alef, K. & Nannipieri, P. (1995). Methods in Applied Soil Microbiology and Biochemistry. Academic Press. pp. 214–216.
Ali-Ehyayi, M. & Behbahanizadeh, AA. (1993). Description of soil chemical analysis methods. Technical Journal No. 893, Soil and Water Research Institute, Tehran, 129 p. (InPersian).
Almadhoun, HR. (2021). Bell pepper classification using deep learning. International Journal of Academic Engineering Research, 5(1): 75-79.
Ashmawi, AE., Salem, GM., Ghazal, MF. & El-Emshaty, A. (2022). Effect of Some indigenous Bacilli and Cyanobacteria Strains inoculants on Growth Characteristics and Productivity of Sweet Pepper (Capsicum frutescens). Australian Journal of Basic and Applied Sciences, 16(6): 1-11. DOI: 10.22587/ajbas.2022.16.6.1.
Bagyaraj, DJ. (1992). Vesicular-arbuscular mycorrhiza: application in agriculture. In: Norris, JR., Read, DJ., Varma, AK. (Eds.), Methods in Microbiology. Academic Press, London, pp. 819e833.
Bakhshande, E., Rahimian, H., Pirdashti, H. & Nematzadeh GA. (2014). Phosphate solubilization potentail and modeling of stress tolerace of rhizobacteria from rice paddy soil in northen Iran. World Journal of Microbiology and Biotechnology, 30: 2437-2447.
Bidondo, LF., Silvani, V., Colombo, R., Pérgola, M., Bompadre, J. & Godeas, A. (2011). Pre-symbiotic and symbiotic interactions between Glomus intraradices and two Paenibacillus species isolated from AM propagules. In vitro and in vivo assays with soybean (AG043RG) as plant host. Soil Biology and Biochemistry, 43:1866-1872.
Bremner, JM. & Mulvaney, CS. (1982). Nitrogen total. In: Page A.L. Miller R.H. and Keeney D.R. (Eds). Methods of Soil Analysis, Part 2. Chemical and microbiological properties. American Society of Agronomy. pp. 595–624.
Chittora, D., Meena, M., Barupal, T., Swapnil, P. & Sharma, K. (2020). Cyanobacteria as a source of biofertilizers for sustainable agriculture, Biochemistry and biophysics reports, 22:100737.
Emami, A. (1996). Plant analysis methods, Soil and Water Research Organization. Publication 982. Vol. 1: 128. (InPersian).
Enayatizamir, N., Noruzi-masir, M. & Ghadamkhanii, A. (2020). Effect of plant growth promoting bacteria on some biological indicators and soil organic carbon forms under wheat cultivation. Journal of Water and Soil Science, 23 (4):171-181 (InPersian).
Gupta, S., Kaushal, R., Sood, G., Bhardwaj, S. & Chauhan, A. (2021). Indigenous Plant Growth Promoting Rhizobacteria and Chemical Fertilizers: Impact on Soil Health and Productivity of Capsicum (Capsicum Annuum L.) in North Western Himalayan Region, Communications in Soil Science and Plant Analysis, 52(9): 948-963.
Homayi, M. (2002). Plants reaction to salinity. National Irrigation and Drainage Committee of Iran, Tehran, 97 p. (InPersian).
Jagnow, G., Hoeflich G. & Hoffmann, K.H. (1991). Inoculation of non-symbiotic rhizosphere bacteria: Possibilities of increasing and stabilizing yield. Angewandte Bottani,. 65: 97-126.
Ju, W., Jin, X., Liu, L., Shen, G., Zhao, W., Duan, C. & Fang, L., (2020). Rhizobacteria inoculation benefits nutrient availability for phytostabilization in copper contaminated soil: drivers from bacterial community structures in rhizosphere. Applied Soil Ecology, 150:103-150.
Katznelson, H. (1946). The rhizosphere effect of mangels on certain groups of microorganisms. Soil Science, 62: 343-354.
Kumar, A., Kumar, J. & Ram, B. (2007). Effect of inorganic and bio-fertilizers on growth, yield and quality of tomato (Lycopersicon esculentum Mill.). Progressive Agriculture, 7 (1and2):151-152.
Kumari, S., Bharat, N., Thakur, A. & Kaushal, R. (2019). Effect of PGPR and BCA on Quality Seed Production of Bell Pepper (Capsicum annuum L.) under Open Field Conditions. International Journal of Economic Plants, 6(4):172-180.
Mahato, P., Badoni, A. & Chauhan, JS. (2009). Effect of Azotobacter and nitrogen on seed germination and early seedling growth in tomato. Researcher, 1(4), http://www.sciencepub.net, sciencepub@gmail.com.
Mahmoudzadeh, M.; Sedqiani, M. & Askari Lejair, h. (2016). Effect of plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi on growth characteristics and concentration of macronutrients in peppermint (Mentha pipperita L.) under greenhouse conditions. Journal of Soil and Plant Interactions, 6 (4) :155-168. (InPersian).
Mohamed, EA., Farag, AG. & Youssef, SA. (2018). Phosphate solubilization by Bacillus subtilis and Serratia marcescens isolated from tomato plant rhizosphere. Journal of Environmental Protection, 9 (03):266.
Naiji, M. & Souri, MK. (2018). Nutritional value and mineral concentrations of sweet basil under organic compared to chemical fertilization. Acta Scientiarum Polonorum: Hortorum Cultus (Ogrodnictwo), 17(2), 167-175.
Nelson, DW. & Sommers, LE. (1996). Carbon, organic carbon and organic matter. In: Sparks, DL. (ed.) Methods of Soil Analysis. SSSA, Madison. pp. 961-1010.
Pandey, A., Palni, L.M. (2007). The rhizosphere effect in trees of the indian central Himalaya with special reference to altitude. Applied Ecology and Environmental Research, 5(1): 93-102.
Pinton, R., Varanini, Z. & Nannipieri, P. (2001): The Rhizosphere. Marcel Dekker, Inc. New York, Basel.
Qessaoui, R., Bouharroud, R., Furze, JN., Aalaoui, ME., Akroud, H., Amarraque, A., Vaerenbergh, JV., Tahzima, R., Mayad, EH. & Chebli, B. (2019). Applications of new rhizobacteria Pseudomonas isolates in agroecology via fundamental processes complementing plant growth. Scientific Reports, 9:12832. doi:10.1038/s41598-019-49216-8.
Rhoades, JD. (1996). Salinity: Electrical conductivity and total dissolved solids. In: Sparks, D.L. (ed.) Methods of Soil Analysis. SSSA, Madison. pp. 417-435.
Ruiz JL. & Sanjuan, MCS. (2022). The use of plant growth promoting bacteria for biofertigation; effects on concentrations of nutrients in inoculated aqueous vermicompost extract and on the yield and quality of tomatoes. Biological Agriculture and Horticulture, 38(3): 145–161. https://doi.org/10.1080/01448765.2021.2010596.
Sadeghi, S, Heidari, G. & Sohrabi, Y. (2015). Effect of biological fertilizer and fertilization management on some growth indices of two maize varieties. Journal of Agricultural Science and Sustainable Production, 25(3): 43-60. (InPersian).
Safirzadeh, S., Chorom, M. & Enayatizamir, N. (2019). Effect of Plant Growth-Promoting Rhizobacteria (Enterobacter cloacae) on Uptake and Uptake Efficiency of Potassium in Sugarcane (Saccharum officinarum L.). Iranian Journal of Soil and Water Research, 50(7): 1689-1699. (InPersian).
Sajedi, N., Madani, H., & Naderi, A. (2011). Effect of microelements and selenium on superoxide dismutase enzyme, malondialdehyde activity and grain yield maize (Zea mays L.) under water deficit stress. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 39, 153–159.
Sarikhani, M.R., Khoshru, B. & Greiner, R. (2019). Isolation and identifcation of temperature tolerant phosphate solubilizing bacteria as a potential microbial fertilizer. World Journal of Microbiology and Biotechnology, 35:126.
Seyed-Sharifi, R. & Khavazi, K. (2011). Effect of seed inoculation with plant growth promoting rhizobacteria (PGPR) on germination components and seedling growth of corn (Zea mays L.). Journal of Agroecology(Quarterly), 4(3):513-506. (InPersian).
Sharma, M., Sharma, V., Delta, AK. & Kaushik, P. (2022). Rhizophagus irregularis and nitrogen Fixing Azotobacter with a reduced rate of chemical fertilizer application enhances pepper growth along with fruits biochemical and mineral composition. Sustainability, 14, 5653. https://doi.org/10.3390/su14095653.
Spence, C. & Bais, H. (2015). Role of plant growth regulators as chemical signals in plant-microbe interactions: a double edged sword. Current Opinion Plant Biology, 27:52–58.
Thangavelu, M. & Arumugam, P. (2019). Influence of an arbuscular mycorrhizal fungus and phosphate-solubilizing bacterium inoculation at stem cutting stage on P uptake and growth of Impatiens walleriana plants in an unsterile field soil. Journal of Horticultural Research, 27(2): 11–22.
Thomas, GW. (1996). Soil pH and soil acidity. In: Sparks, D.L. (ed.) Methods of Soil Analysis. SSSA, Madison. pp. 475-490.
Vejan, P., Abdullah, R., Khadiran, T., Ismail, S., Nasrulha, Q. & Boyce A. (2016). Role of plant growth promoting rhizobacteria in agricultural sustainability- a review. Molecules, 21 (5):573.
Wang, J., Li, R., Zhang, H., Wei, G. & Li, Z. (2020). Beneficial bacteria activate nutrients and promote wheat growth under conditions of reduced fertilizer application. BMC Microbiology, 20. doi:10.1186/s12866-020-1708-z.
Zhang, L., Jing, Y., Xiang, Y., Zhang, R. & Luc, H. (2018). Responses of soil microbial community structure changes and activities to biochar addition: a meta-analysis. Science of the Total Environment, 643, 926–935.