ABSTRACT
Soybean (Glycine max L.) plays an essential role in human nutrition as a protein source, and in
plant nutrition as a N source. The rate of N fixation varies depending on the cultivars and compatibility
between the inoculated Rhizobium strain and the host cultivar. Characterizing the nodulation
regulatory (Rj) genes is necessary to determine the compatibility of cultivars and Rhizobium
strains. Rj genes were previously identified based on inoculation tests and PCR analyses. The six
cultivars Yezin-3, Yezin-7, Yezin-11, Shan Seine (Local), Madaya (Local), and Hinthada (Local)
were identified as harboring the Rj4 gene. Two cultivars, Yezin-6 and Yezin-8, were classified as
non-Rj-gene harboring. Two other cultivars, Yezin-9 and Yezin-10, were identified as Rj3- and
Rj2Rj3-gene harboring, respectively. Ours is the first report on Rj3- and Rj2Rj3-gene harboring cultivars
in Myanmar. We evaluated Myanmar soybean cultivars for symbiotic effectiveness, relying
on the standard strain Bradyrhizobium japonicum USDA110. In our first experiment, the soybean
cultivar Yezin-11 (Rj4) showed the highest N fixing potential. Based on their potential for fixing N
and nodulation, the top six soybean cultivars were Yezin-11 (Rj4), Yezin-9 (Rj3), Yezin-6 (non-Rj),
Yezin-8 (non-Rj), Yezin-3 (Rj4) and Yezin-10 (Rj2Rj3). These cultivars were selected for a second
experiment, which revealed that the N fixation, nodulation, and plant growth of Yezin-11 (Rj4)
*Corresponding author.
A. Z. Htwe et al.
2800
were superior to the other cultivars. We conclude that Yezin-11 (Rj4) is the most efficient cultivar
for nodulation and N fixation when inoculated with B. japonicum USDA110.