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

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.