TITLE:
Low-Density Co-Inoculation of Myanmar Bradyrhizobium yuanmingense MAS34 and Streptomyces griseoflavus P4 to Enhance Symbiosis and Seed Yield in Soybean Varieties
AUTHORS:
Khin Myat Soe, Takeo Yamakawa
KEYWORDS:
Bradyrhizobium yuanmingense; N2 Fixation; S. Griseoflavus P4; Seed Yield; Soybean
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.9,
August
30,
2013
ABSTRACT: This study examined whether low-density co-inoculation of Myanmar Bradyrhizobium yuanmingense strain MAS34 and Streptomyces griseoflavus P4 would enhance nodulation, N2 fixation, and seed yield in two soybean varieties. A field experiment was
conducted during the July to November 2012 growing season at Kyushu University
Farm, Japan, using a split-plot design with three replications and the
following four treatments: T1, an uninoculated treatment with peat moss
(uninoculated); T2, a single inoculation with S. griseoflavus P4 (P4); T3, a single inoculation of B. yuanmingense MAS34 (MAS34); and T4, a dual inoculation of P4 with MAS34 (P4 + MAS34). Two
varieties of soybean, Yezin-3 (Rj4) and Yezin-6 (non-Rj), were used. The N2 fixation activity of soybean was evaluated by the relative ureide method using
xylem solute from root bled sap at the early pod-fill stage (R3.5). Dry matter
production, N2 fixation, and seed yield were significantly (P 0.01) different between the inoculated treatments.
The effect of variety was also significant
(P 0.05) for nodule dry weight at
the V6 stage, percentage of N derived from the atmosphere at the R3.5 stage,
and seed yield at the maturity stage. The number of nodules on the tap roots
was significantly higher in Yezin-3 than in Yezin-6. The single inoculation of
P4 did not have a significant effect on dry matter production, N2 fixation, and seed yield in either soybean variety. The dry matter production,
relative ureide index, percentage of N derived from the atmosphere, and seed yield were
significantly (P 0.01) enhanced by a single
inoculation of MAS34 in Yezin-3 and by dual inoculation of P4 + MAS34 in Yezin-6. These results indicate that low
inoculum concentrations (105 cells seed-1) increase N2 fixation and seed yield in these soybean varieties under open field conditions.
Myanmar B. yuanmingense MAS34 and S. griseoflavus P4 are expected
to be useful biofertilizers for soybean production.