Symbiotic Activity of Lupin when Adding Zoohumus to the Substrate

The aim of the work was to study the effect of various fertilization technologies on the processes of growth, synthesis of photosynthetic pigments, nodule formation and the dynamics of changes in their nitrogenase activity in different varieties of lupine (white and narrow-leaved). The emphasis in the work was shifted to the additional positive effect obtained from the introduction of a liquid extract of black soldier fly zoohumus (Hermetia illucens) into the lupine-rhizobial agrocenosis. According to the biomass indicators, it was found that narrow-leaved lupine was more responsive to the organo-microbial effect, the increase in which, on average, by variants amounted to 36%, compared to the control. On white lupine, it reached only 9%. It should be noted that in terms of vegetative biomass accumulation, white lupine prevailed over narrow-leaved lupine in all experimental variants by an average of 3 times. However, with a relatively small increase in weight, narrow-leaved lupine showed an increased synthesis of total chlorophyll. On average, the increase in it from the effect of the organomicrobial consortium was 19%. Regarding the values of symbiotic activity, a positive effect of zoohumus was recorded against the background of inoculation, which was reflected in an increase in the number, weight and nitrogenase activity of formed nodules in the vegetation phases. A direct correlation was found between these indicators. The highest peak in fixation for both species occurred at the budding phase, amounting to 17 059 C₂H₄ /g^–1 h^–1 nmol for white lupine and 2719 C₂H₄ /g^–1 h^–1 for narrow-leaved lupine. As both lupine species matured, the number of nodules decreased and the process of symbiotic nitrogen fixation decreased. The results obtained indicate a positive effect of H. illucens zoohumus on the studied indicators and allow us to recommend the use of its liquid extracts in lupine cultivation.