Selection of salinity tolerant rhizobial isolates from wild and cultivated legumes in arid region of Libya (Fezzan)

Abstract

Eighty-four isolates were isolated from different legumes (Pisum sativa, Vicia faba, Cicer arietinum, Medicago sativa, Trigonella foenumgraecum, Lotus halophils, Astragalus fructicus, Hippocarpis, Viciae rvilla, V. narbonensis, Medicago polymorph and M. littoralis) Planted or wild in different locations of the dry zone of Libya (Fezzan) These isolates were tested for their ability to tolerate the salts of sodium, potassium and magnesium chloride on yeast extract and menthol, some rhizobia isolates of the fenugreek (Trigonella foenumgraecum) It was tested on alfalfa plant (Medicago sativa) This is to determine the level of sodium chloride salt which allows the formation of Symbiosis and nitrogen fixation, results of the salinity test on the steel medium were subjected to numerical analysis (Numerical Taxonomy), where three groups were formed. Three groups were formed. Most of the isolates of the first group were resistant to all tested salts. They grew at a salinity level of 8.5 to 9.5%. The isolates of the second group were sensitive to sodium and magnesium chloride salts and less resistant to potassium salt. Group III isolates were different in their response to salts tested, the results of the test of the growth of some saline resistant isolates in the liquid medium were similar to their growth on the middle of the agar, where the concentration allowed growing between 5-8% of sodium chloride, the growth-inhibiting focus was between 6-9%, effect of sodium chloride salt on the symbiosis between alfalfa plant and some isolates (T3 and T5) from the fenugreek showed that the maximum concentration allowed for the formation of Symbiosis was between 0.8 and 1% of chloride Sodium, the higher the concentration of salt, the smaller the number of nodes formed, and the 1.5% level was a disincentive to the Symbiosis process.