## 1 Introduction  
In the era of climate change, one of the challenges for the modern world of science is to develop foundations which will enable the improvement of the physiological processes of plants, especially functional crops, and thus make better use of their biological potential. In recent years, there has been growing interest in legumes [1]. The greatest advantage of these crops is their ability to coexist with bacteria of the _Rrizobium_ genus, which can fix atmospheric nitrogen [2]. Due to the requirements of modern agriculture, it is necessary to search for new technologies that support the development and yield of legumes because these crops contain large amounts of protein and have a strong stimulating effect in crop rotation. Microorganisms have developed various mechanisms which allow plants to adapt to the changing environment [3]. Researchers focus on the development of bioinoculants based on plant growth-promoting rhizobacteria (PGPR) [4]. The use of organic biofertilisersand biopesticides containing PGPR isolates is an alternative strategy for reducing mineral fertilization [5; 6].  
The name _PGPR bacteria_ is more and more often used to describe the bacteria which live in the rhizosphere and colonise plant tissues, thus affecting the growth, development, and productivity of plants. Inoculation with bacterial consortia ensures more balanced nutrition and improves the uptake of nutrients by plants [7; 8]. Among the plant growth-promoting bacteria, _Bacillus_ sp. and _Pseudomonas_ sp. are important and dominant genera, which aggressively colonise the rhizosphere of various crops and exhibit a broad spectrum of antagonism against numerous pathogens [9]. Plant growth is directly stimulated in various ways, e.g., through the synthesis of phytohormones as well as the stimulation of the growth of the root system. Moreover, PGPR decompose organic compounds and thus provide essential nutrients to plants; they also reduce the level of harmful ethylene [10; 11; 12].  
There are numerous reports in reference publications which indicate that the coinoculation (double inoculation) of plants with symbiotic bacteria and endophytes improves the physiological development of legumes [13; 14]. In view of the challenges of modern agriculture, the search for methods supporting the development and yield of legumes, especially methods involving microbiological technologies, falls in line with the assumptions of the European Green Deal and the EU Biodiversity Strategy for 2030. These documents emphasise the significance of sustainable plant production, the need to develop agrobiology and environmentally friendly solutions, and they assume an increase in the area of plantations with crops grown in ecological production systems.  
This study emphasises the positive effect of microbial consortia composed of _Bradyrhizobium_ bacteria isolated from commercial preparations and selected endophytes on the biometric parameters of plants grown in a model experiment.  
The aim of the study was to assess interactions between the symbiotic bacteria (_Bradyrhizobium_ sp. isolated from commercial preparations Nitragina and Nitrolora) dedicated to white lupine and selected endophytes (_Pseudomonas fluorescens_ or _Bacillus subtilis_) used for seed coinoculation. In addition, selected morphological traits of the plants were measured (the weight and length of the aboveground and belowground parts) after the applied inoculation/coinoculation. The degree of root colonisation by selected endophytes used as single inoculants and in interaction with bacteria of the _Bradyrhizobium_ genus was also determined.