Fetene Masresha (PhD)Asfaw Zemede (PhD)G/ Egziabher Yemane2018-07-172023-11-082018-07-172023-11-082001-03http://etd.aau.edu.et/handle/123456789/8998Physiological investigations were made on 25 barley (Hordelllll vulgare L.) landraces and acceSSIOns to screen for fi'ost resistance. Samples were collected fi'om three sites, in Amhara administrative rcgion, north Wolo and Tigrai administrative region, south and east Tigrai (north Ethiopia) in November 1999. Experimental work was conducted fi'om January to March after the seedlings have been grown for about a month in an open field at the Science Campus, Addis Ababa University. Accessions fi'om mCR were included for altitude ranges from which field collections were not made. Etlmobotanical study was also conducted in order to get infOimation on the indigenous practices that may be enabling fanners to continue barley cultivation in fi'ost prevailing areas. In the surveyed areas, at least half of the fatmlands of the peasant fanners were prepared for barley cultivation during the main rainy season, the rest being for legumes as well as wheat. The interviewees indicated enviroillnental stresses such as insufficient rainfall, low soil fertility and fi'ost effect as main limiting factors of barley production. They also responded that none of them had ever practiced selection of barley for resistance to fi·ost. However, early maturing barley types are cultivated in higher altitudes when there is scarcity ofrainfall, which also escape severe fi·ost. The late bariey landraces were neglected by the fatmers due to the unreliable rainfall. The ethnobotanical investigation indicated that barley is used as a major food grain alone or in combination with other cereals utilized in different forms of foodstuffs. Moreover, it has both religious and cultural values. A total of 25 samples were evaluated using conductivity and chlorophyll a fluorescence methods. Based on membrane stability and fluorescence studies, the potential survival temperature of the samples rangcd from -6.48 °C to -8.64 °C. Barley landraces from Abune-Yosef, Smp3 (Tedowasha) and Smp13 (Awarye), which were collected from altitudes of 3270 and 3300m as\. as well as accessions AccS (Kokufa) and Acc2 (Chellka) from Bale altitude of2430m and l6S0m as\., respectivel y were found to be relatively the most frost resistant in both methods. Samples Smp21 (Saeda-Shewa) from Tsibet-Embahasti altitude of3100m as\. as well as Acc\3 from Arsi altitude of 2800m as\. were found to be relatively the most susceptible in conductivity and fluorescence analysis methods, respectively. The study showed that -5°C (using conductivity method) and -4 °C (using fluorescence analysis) were the highest sub-zero temperatures at which the samples could be differentiated easily. Altitude of site of sample collection had a slight positive correlation with fi'ost resistance. The two methods had consistency and showed variations among the samples and are thus recommended for screening barley landraces and accessions. Fluorescence analysis was found to be a more sensitive method.enBiologyThesis