The interaction effect of inoculation of broad bean seeds with proper
strain of Rhizobium leguminosarum biovar viciae, on damping-off and root-rot
diseases caused by Rhizoctonia solani and viral infection by bean common
mosaic virus (BCM) was studied under sterilized and non-sterilized soil.
Data showed that R. solani when infested solely in sterilized soil caused
the highest percentage of post-emergence damping-off and root-rot disease.
While, rhizobial and viral inoculation reduced of studied fungal infection either
when used solely or in combination. Highest percentage of viral infected plants
was observed with viral inoculation solely whereas, viral infected plants were
decreased in other treatments specially in case of rhizobial inoculation in both
investigated soils. The highest values of fresh and dry weights of root nodules
were recorded with rhizobial inoculation treatrnent whereas, root nodules
weights were highly decreased when R. solani or BcM vwere inoculated with
Rh. leguminosarum either solely or in combination.
Total bacterial counts and actinomycetes were high in rhizosphere of
rhizobial inoculated plants either solely or in combination with viral infection
and this trend was observed at all gowth stages. Rhizosphere of inoculated
plants with Rh. leguminosarum and./or BCMV contained lower populations of
fungi than that of uninoculated plants.
Rhizobial inoculation treatments gave significant increase in plant
height, no. of leaves/plant, no. of flowers/plant, fresh and dry weights of root and
shoot system when inoculated solely as well as when associated either with R.
solani or BCMV regardless the type of soil. On the contrary, all growth
characters were decreased in case of viral or fungal infection each one solely, but
increased with their combination regardless the type of soil.
Also, total nitrogen and crude protein were increased with rhizobial
inoculation either solely or combined with R. solani or BCMV. Except the
control treatment, the lowest value of total nitrogen and crude protein was
observed with fungal infestation solely in sterilized soil. Total phosphorus was
the highest in case of fungus combined with virus or Rhizobium combined with
virus treatments in sterilized and non-sterilized soil, respectively. While, the
lowest value of total phosphorus was obtained with fungal infestation solely in
sterilized soil.
Chlorophyll a, b and c greatly increased with rhizobial inoculation
either solely or in combination with R. solani or BCMV regardless the type of
soil. Except the control, chlorophyll a, b and c levels were the largest in case of
R. solani, BCMV or R. solani +BCMV, respectively. in sterilized soil. with
chlorophyll b or c in case of viral inoculation solely was lower than other
treatments in non-sterilized soil.
Total carbohydrates level was the highest with rhizobial inoculation
solely in both soils, while, the lowest level of total carbohydrates was observed
with R. solani, BCMV each one solely in sterilized and non-sterilized soil,
respectively. On the other hand. rhizobial inoculation in sterilized soil combined
with either R. solani or BCMV showed increase in carbohydrates level compared
with inoculation with either R. solani or BCMV each one solely. |
