Table 2. Plant responses to inoculation of Glycine max cv. Osumi with S. fredii SMH12 and derivatives.

Inoculant	Number of nodules	Fresh mass of nodules (g)	Plant-top dry mass (g)
None	0±0*	0±0*	0.48±0.11*
SMH12	124.30±12.06	1.56±0.20	1.34±0.18
SVQ648	0±0*	0±0*	0.46±0.10*
SMH12 (pME6863)	76.20±16.02*	1.04±0.29	1.10±0.30
SMH12 (pME6000)	131.00±22.68	1.60±0.38	1.35±0.25

Data represent means ± sd of six soybean jars. Each jar contained two soybean plants. Determinations were made six weeks after inoculation. Mutant nodD1 and the lactonase strain parameters were individually compared with the parental strain SMH12 parameters by using the Mann-Whitney non-parametric test. Values tagged by * are significantly different at the level α = 5%.