The microbial density in soil and rhizosphere of two broad bean varieties Giza 2 and Rebaya 40 was estimated at the different stages of plant growth. The results of the investigation showed the following: The total microbial counts, actinomycete and fungi counts were found to be higher in the rhizosphere than in soil apart in all investigated samples at different stages of plant growth for the two broad bean varieties. The rhizospheric total microbial counts increased with the increase of plant age till the flowering stage, where maximum counts were attained, then decreased. This was true for both broad bean varieties. The rhizosphere effect (R/S ratio) on the total microbial counts and the R/S ratio of Fungi counts were higher in Rebaya 40 than Giza 2 in the early stages of plant growth up to the flowering stage. The opposite was found in the later stages of plant growth. The R/S ratio of actinomycets counts was found to be positive, but not very high, for both the two broad bean varieties. The number of nodules and their dry weight increased with the increase of plant age up to the late pod-formation stage than decreased. Both the broad bean varieties showed the same trend. |
