engleski

Symbiotic efficiency of indigenous Bradyrhizobium japonicum strains used in soybean production in agroecological conditions of Croatia

Success of soybean seed inoculation very often depends on competitive indigenous B. japonicum strains found in soils of favourable physical and chemical characteristics. The presence of adapted and highly competitive indigenous B. japonicum strains in soil can limit the inoculation response of commercial inoculants. The main goal of these investigations was to select the most efficient B. japonicum strains isolated from soils of Croatia. Geneticaly differentiated strains used for inoculum preparation were as follows: S3, S5, S6, S7, S8, S10, S13, S14, S15 (group Ib); S4, S9, S12 (group II) and reference strain D344 (group Ia. All strains are from collection of Department of Microbiology. For the genetic differention of strains RAPD analysis was used. During the three years investigations in field experiments, symbiotic efficiency of indigenous isolates and reference strain D344 was tested as well as their compatibility with soybean cultivars Nada and Tisa. In all three years of investigations, significantly lower values for number and nodule dry weight were determined on control variants in respect to all variants inoculated with indigenous strains as well as with D344 strain. Statistically significant differences between indigenous isolates were not determined during the certain years of investigations. Statistically verified influence of cultivar on number and nodule dry weight was determined. Inoculation with all tested B. japonicum strains caused significant yield increase. The highest seed yields were reached using indigenous S4, S12 and S9 strains which represent a very distinct and separate group of nodulating bacteria based on RAPD method results. Results of investigations clearly show significance of B. japonicum strains selection for succesful and cost effective soybean production in Croatia.

soybean; symbiotic efficiency; Bradyrhizobium japonicum

nije evidentirano