Biotechnology

Permanent URI for this collection

http://etd.aau.edu.et/handle/12345678/146

Browse

Browsing Biotechnology by Author "Adal Musa"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Phenotypic and Symbiotic Characterization of Grass Pea (Lathyrus Sativus) Rhizobial Isolates from Some Major Growing Areas Of South Wollo and West Shoa , Ethiopia
    (Addis Ababa University, 2009-07) Adal Musa; Assefa Fassil (PhD)
    Grass pea (Lathyrus sativus) is the most widely distributed and the third most important pulse crop in Ethiopia. It grows in a wide range of altitudes and survives in scarce moist conditions and fixes nitrogen with rhizobia and performs well in less fertility soils. However, the effectiveness in nitrogen fixation varies depending upon the host varieties, type of strain and different environmental characters. It is, therefore, necessary to evaluate the efficiency of different isolates from different sampling areas. Thus, 68 grass pea rhizobial isolates (47 from South Wollo and 21 from West Shoa) were isolated and characterized on the basis of different characters. These isolates were reinoculated on pouch culture using “Wasse” variety of grass pea to authenticate nodulation and determine their symbiotic effectiveness. All but 5 isolates were authenticated as root nodule bacteria with their capacity to infect and nodulate their parent host. Most of the isolates displayed fast doubling time (1.2-4hrs) and large colonies (2-6.0 mm) and changed the BTB-YEMA media to yellow which showed that they are fast growing rhizobia and then categorized into R. leguminosarum bv. viceae. The preliminary screening of the isolates for symbiotic effectiveness on pouch culture showed that isolates AAUGR (31, 37, 41 and 47) of South Wollo and AAUGR (48, 49, 52, 59, 60, 61, 66 and 67) of West Shoa that comprised of 19% of the isolates were highly effective whereas, 43% were found to be effective. Three highly effective isolates from South Wollo (AAUGR 31, AAUGR 37, and AAUGR 41) and four highly effective isolates from West Shoa (AAUGR 48, AAUGR 59, AAUGR 61, and AAUGR 67) were reinoculated into soil culture to evaluate their performance in the natural environment (soil). All the selected isolates were found to accumulate 112-149 % of SDM that was higher than the controls. Isolate AAUGR 37 (SW) accumulated the highest SDM of all the inoculated treatments and the controls. All the selected isolates were found to perform better on pot culture than on pouch culture. Almost all of the isolates were able to grow at extremely low and high pH, low and high salt, low and high temperature, and utilized a wide range of carbohydrate and nitrogen sources and displayed high resistance to several antibiotics indicating that the isolates can compete in their natural environment. The result of the numerical analysis also showed the existence of diversity among the tested isolates.