The main aim of these investigations was to test the soybean inoculation with different Bradyrhizobium japonicum strains and application of Bioalgeen S90 as a growth regulator on photosynthetic pigments level and soybean yield in agroecological conditions of eastern Croatia. Regarding the main aim of investigations, greenhouse experiment as well as field trials were carried out in order to achieve the answers for more efficient use of biological nitrogen fixation. Greenhouse experiment pointed out positive effect of interaction between Bioalgeen S90 and seed inoculation with B. japonicum strain D344 on photosynthetic pigments level. Based upon these resuts, two factor field trials on two locations were established by split-plot method in randomised block design. In combined statistical analysis over locations, it was determined that Bioalgeen S90 had significant influence on chlorophyll b and a+b content. Application of this growth regulator resulted in significant increase of soybean yield as well. Regardless of B. japonicum strain used, inoculation had a significantly positive effect on chlorophyll a, b and a+b content. Statistical analysis showed superior effect of inoculation with D344 and USDA 110 B. japonicum strains compared to control, uninoculated variants. Soybean seed yield is the most significant indicator of succesfull agrotechnics and cultivar selection for certain agroecological area. Yield differences indicated that combination of Bioalgeen S90 as a growth regulator together with D344 and USDA 110 B. japonicum strains had the most important influence on yield increase.

Agronomija