Abstracts |
Seedlings of black locust (Robinia pseudoacacia L.) were coinoculated with a
local effective strain Rhizobium species RpI1 and with Glomus deserticola. The effects of both
symbioses on plant growth were studied in a greenhouse experiment with four treatments: two
single inoculations, one double inoculation, and no inoculation, in a nonsterilized substrate
from a desurfaced soil. A synergic effect was observed because double inoculation produced
significantly higher shoot biomass, nodule biomass, and N-2 fixation, as measured by the
acetylene reduction assay (at least 93%, 50%, and 192%, respectively) than any single inoculation
treatment and than noninoculated controls, which were nodulated by soil-born rhizobia.
Mycorrhizal colonization did not improve the growth of control plants, but it did significantly
improve the specific nitrogenase activity of plants inoculated also with Rhizobiuln species RpI1
by 77%. We conclude that prenodulation of plants is necessary for better growth on harsh
substrates and that mycorrhizal colonization helps nodulated plants reach their P demand in
P-limited soils. |