General Commission of Scientific Agricultural Research-
Deir Ezzor Research Center
Faculty of Agriculture, Al-Ba’ath University,
The experiment was conducted at Al-Mreiyeh research station in Deir Ezzor during two growing seasons (2006- 2007) to study the effect of three levels of irrigation water salinity (F=0.9 dS/m, S1=6 dS/m, and S2=12 dS/m) on the number of microbiological population in and out rhizosphere of four forage crops. Two of these crops were winter grown namely barley Hordium vulgare var. ACSAD 176 and Triticale Triticosecale) and two summer grown namely sorghum Sorghum bicolor var. Izraa 7 and Millet Pennisetum glaucum var. 24.
The results showed that irrigating barley and triticale crops during the first season with medium salinity water and high salinity water reduced the number of the studied microorganisms in and out the rizhosphere insignificantly compared with the irrigation with low salinity water “F”. The continuation of irrigation with the medium salinity water “S1” and high salinity water “S2” during the second growing season on sorghum and millet reduced the number of microorganisms (Amonification bacteria, Bacteria using mineral nitrogen, Oligonitrophiles, Azotobacter) and Mesophilic cellulose decomposing microorganisms, and actinomycetes significantly, while the differences were not significant for Spore-forming bacteria Bacillus and fungi compared with “F” quality irrigation water.
The results also showed that irrigation with medium salinity water “S1” and high salinity water “S2” increased the salinity of the soil and salts were accumulated in the soil profile mainly under “S2” salinity conditions, which reduced the weight and length of barley and triticale roots insignificantly using medium salinity water “S1”, while the difference between “F” and “S2” treatments were significant.
On the other side, the results showed that irrigation with medium salinity water “S1” reduced barley and triticale yield (winter-grown crops) insignificantly compared with “F” treatment, while the
differences in yield were significant between “F” and “S2″ treatments. Barley grain weight decreased when irrigation with” S2″ treatment (25.81%) and triticale grain weight decreased (55.51%) when irrigation with “S2” treatment, which means that barley is more tolerant to salinity than Triticale.
On the other hand, the reduction of sorghum and millet yield (summer crops) were significant compared with “F” treatment after the continuation of irrigation with “S1” and “S2” water treatments. In terms of sorghum, fresh and dry matter decreased by increasing water salinity by (31.26%, 59.15%) respectively, using S1 water salinity, and by (59.15%, 68.62%) respectively, using S2 water salinity. Millet fresh and dry matter decreased by increasing water salinity by (31.26%, 59.15%) respectively, using S1 water salinity, and by (59.15%, 68.62%) respectively, using S2 water salinity, which means that millet is more tolerant to salinity than sorghum.