Agriculture Reference
In-Depth Information
Figure 2.Shoot dry weight of
Pisum sativum
plants grown 30 days under 0 (A) and 90 (B) mM NaCl
and inoculated with different
Rhizobium leguminosarum
strains and isolates. Striped bars represent
unnodulated plants. Single colour bars represent nodulated plants. Colour is indicative of isolates and
strains salt tolerances: white- sensitive; grey- tolerant and black- extremely tolerant.
When no sodium chloride was added, all isolates established efficient symbiosis, as
judged by the formation of pink nodules, although growth responses varied greatly (Figure
2A). Shoot biomasses were significantly lower than controls supplied with nitrate. AWA 1-2
yielded a significant higher growth than the other isolates. In the presence of 90 mM NaCl,
few isolates were able to establish an efficient symbiosis (Figure 2B). Unsuccessful symbiosis
under salt stress may be due to a failure in the establishment of rhizobia in the rhizosphere, or
a failure of the infection process due to the effect of salinity (Singleton and Bohlool, 1984).
Under salt stress, none of the sensitive strains was capable to nodulate pea plants, but all
extremely tolerant strains were able to establish efficient symbiosis, except for strain AS 24-
