GEOGRAPHICAL, ALTITUDE AND AGROECOLOGICAL DIFFERENTIATION OF ISOZYME AND HORDEIN GENOTYPES OF LANDRACE BARLEYS FROM ETHIOPIA - IMPLICATIONSTO GERMPLASM CONSERVATION

An analysis of the variability of genes encoding six isozyme systems ( 15 loci) and two storage proteins (2 loci) in landrace barley from Eth iopia is reported. The materials consisted of populations collected fr om sites as low as 1650 and as high as 3750 meters, covering a wide ra nge of agro-ecological conditions and geographical areas. Of the 17 lo ci 7 were polymorphic and 10 monomorphic when the 95% criterion of pol ymorphism was applied. Despite the disproportionate monomorphic loci, polymorphism was detected in all populations when this criterion is us ed. The populations were found to possess fairly low mean number of al leles per locus (A = 1.5), low mean value of expected heterozygosity ( H = 0.134) and a fairly high mean percentage of polymorphic loci (P = 35.3%). The mean F-ST = 0.474 for the populations is typical of inbree ding species. The result indicated that allelic richness is concentrat ed in altitude class 3 (2500-3000 m) followed by altitude class 1 (<20 00 m). Altitude class 2 (2000-2500) holds an intermediate place though it is the highest in terms of expected heterozygosity (H = 0.245). Hi gher genetic diversity is concentrated in some geographical regions su ch as Shewa, Arsi, Bale compared to others (Welo, Gamu Gofa, Gojam). G enetic differentiation among the agro-ecological zones was more profou nd than both among the altitudes and among regions. Correlation analys is between phenotypic diversity (Shannon-Weaver diversity index) and e xpected heterozygosity (H) for isozyme/hordein loci revealed non signi ficant associations except with respect to agro-ecological zones. Zn g eneral, it was detected that sites in highland areas in central and no rthern regions may be more desirable for in situ conservation than sit es in peripheral regions in terms of isozyme/hordein diversity and cur rent rate of varietal replacement.