Effects of genotype and bradyrhizobium inoculation on morphological traits, grain yield and protein content of soybean varieties

Soybean crop production in Serbia involves seed inoculation by N-fixing bacteria just before sowing time. The main objective of the current work was to assess the impact of the genotype and inoculation on range of morphological and yield traits of soybean (Glycine max L. Merrill), as well as the total protein content. The experiment was conducted on chernozem soil, where soybean was previously grown. The six local varieties were used, where each variety was sown, in three replicates for both inoculated and non-inoculated treatment. The following morphological traits were analysed: the plant height, number of lateral branches, distance to the first pod, number of pods per plant, pods (containing seeds) weight per plant, seed weight per plant, and the total grain yield. The total protein content in seeds was determined by standard analytical method, while subtle differences in qualitative protein composition were assessed using Raman spectroscopy. The total protein content varied from 39.6 to 42.15 %. Performance of inoculation resulted in an increase of the plant height and the distance to the first pod, although not in all tested varieties. The highest and the lowest plant height values were observed for non-inoculated variety Dana (59.23cm) and Sava (80.03cm), respectively. The effect of genotype was much more expressed causing differences in almost all tested characters, except for the total protein content. However, Raman spectroscopy analyses revealed distinct discrimination among surveyed varieties, and differences between inoculated and non-inoculated plants in qualitative composition of seed proteins.