Effect of temperature on survival and efficiency of root nodule bacteria
1987
Yousef, A.N. (Scientific Research Council, Baghdad (Iraq). Agriculture and Water Resources Research Centre, P.O. Box 2416) | Abdul-Ridha, H.A. (Basrah Univ., Basrah Province (Iraq). Coll. of Agriculture)
The effect of five incubation temperature lavels, ranged from 25-55 deg C, on the survival and N2-fixation efficiency of Rhizobium japonicum strains (sb-16) and (61A18) and R. leguminosarum, nodulating mung beans, strain (M-10) and a local isolate (M-1) was studied under controlled conditions. All the bacterial cultures were unable to survive one week at 55 deg C. The same effect was noticed at 45 deg C with the R. japonicum strains but not with the R. leguminosarum cultures. Isolate (M-1) and strain (M-10) were able to survive at this temperature for two and six weeks, respectively, despite the marked decrease in their viable cell counts. The highest population density of all examined cultures was found at the incubation temperature of 25 and 35 deg C. Generally, inoculation of soybean and mung bean seeds with the specific Rhizobium, previously incubated in a sterilized soil at 35 or 45 deg C, improved their ability to fix N2 throughout increasing the number of nodules, shoot dry weights and nitrogen content of the plants. The response to inoculation was more obvious when the cultures were added as rock phosphate coated inoculants than mounted on a river sediment base carrier
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