Isn't Rhizobium leguminosarum for leguminous plants?
In the past I did some reading on this. I know some strains are definitely beneficial to non-legumes. Here is one study I had bookmarked.
http://plato.acadiau.ca/isme/Symposium26/hoflich.PDF
Results
Plant growth promotion
Only one of 14 strains tested that stimulated the growth of clover or alfalfa also stimulated
the growth of non-legumes. In greenhouse experiments,
R. leguminosarum bv.
trifolii R39,
isolated from red clover nodules, promoted the shoot growth of wheat, maize, oil radish,
rape and mustard about 19 to 33 %, in comparison with non-inoculated controls. In field
experiments on loamy sand seed inoculations with peat formulations of strain R39
significantly and consistently stimulated the growth of red clover, clover-grass-mixtures (7
%), maize (10 %), spring wheat 8 %), spring barley (16 %) and oil radish (21 %)[1, 2, 3].
On sandy loam the effects on non-legumes were not significant. Also, not all maize varieties
reacted with a growth stimulation to
Rhizobium inoculation [2].
In field experiments both the uptake of nitrogen [15-16 %+], phosphorus [16-23 %+],
potassium [21-30 %+] in the juvenile stage of maize, and the yield of shoots [13-16 %+] and
roots [10-22 %+] was significant stimulated [2].
ABSTRACT
Rhizobium leguminosarum bv.
trifolii strain R39, isolated from red clover nodules, in field
experiments on loamy sand, stimulated not only the growth of red clover but also the
growth of maize, spring wheat, spring barley and oil radish. After seed inoculation, this
strain colonized the rhizosphere of these plants and migrated to nearby non-inoculated
spontaneous weed plants. Following crop harvest the
Rhizobium strain was able to re-
establish in the rhizosphere of plants subsequently grown in the same plots. Microbiological
and electron microscopical investigations on maize and wheat showed, that R39 had
colonized the rhizoplane of the active growing roots [zone of emerging laterals and root tip
mucigel]. The production of phytoeffective metabolites by strain 39 may be important for
the stimulation of root growth and nutrient uptake by plants.
