Effect of plant growth-promoting rhizobacteria on growth and yield of sweet pepper under different levels of mineral fertilization

At Kaha Experimental Farm in Qalubia Governorate, two seasons of fieldwork (2024 and 2025) were carried out to examine how sweet pepper reacts to various mineral fertilizer rates in conjunction with plant growth-promoting rhizobacteria (PGPR). The experimental design was split-plot, where the mineral fertilizer by rates 50 percent, 75 percent and 100 percent of recommended practice were assessed in main plot, while PGPR inoculated (Bacillus subtilis, Pseudomonas putida, or a combination of them) applied to the secondary plots. Results showed that, the greatest sweet pepper growth parameters including fresh and dry weights; and leaf area) achieved with a 75 percent mineral fertilizer treatment. Also, the same treatment produced the highest values for important yield indicators as fruit weight, number of fruits per plant, early and total yield. Mixed PGPR inoculum has a beneficial effect which resulted in soil pH and electrical conductivity (EC) decreasing and consequently, improving plant performance. In order to achieve more sustainable sweet pepper, it is generally advise to use 75 percent of the mineral fertilizer in conjunction with the mixed of PGPR inoculum. This combination increased sweet pepper growth, yield, and fruit quality compared with lowering chemical fertilizer rates regardless of these lower rates considered more environmentally friendly farming practices.