Effectiveness of Bradyrhizobium japonicum inoculation on nodulation dynamics in Glycine max (L.) roots

Abstract

Bradyrhizobium japonicum bacteria on the intensity of nodulation during nine phenophases (R1-R7) in relation to the isoflavone content in soybean seeds. Nine domestic soybean varieties were sown in three replicates, with Bradyrhizobium japonicum inoculated and non-inoculated seeds. The different morphological characteristics of nodules, the number and mass of nodules were studied during plants’ ontogenesis. The content of individual isoflavones in the sowing seed material was determined using high performance liquid chromatography mass spectrometry (HPLC-MS). The most abundant isoflavone was acetylgenistin in the variety Galeb (2741.4 μg/g), and the highest content of all isoflavones was recorded in the variety Gorštak (8117.7 μg/g). The variety Sava of the inoculated treatment exhibited the highest average values of the nodule mass (21.1 mg) and the highest number of nodules (23.3) in the phenophase, in which 10% of pods reached full length (R4). The average values of mass and number of nodules were calculated for the entire vegetation period, being higher in the inoculated treatment. There was no positive correlation between the content of isoflavones in seeds and the number and mass of nodules. The impact of quantity of isoflavone on nodulation intensity in soybeans was not significant,, which could be related to already saturated soil with nitrogen-fixing bacteria.

Keywords

• Bradyrhizobium japonicum
• isoflavones
• nitrogen fixation
• nodule
• soybean