PATTERNS OF MORPHOLOGICAL DIVERSITY IN TETRAPLOID WHEAT (TRITICUM-TURGIDUM L) LANDRACES FROM ETHIOPIA

Thirty-four tetraploid (2n = 4x = 28) wheat (Triticum turgidum L.) lan drace populations collected from four regions in Ethiopia, and consist ing of 4099 entries were characterized for glume colour, glume pubesce nce, beak awn, seed colour and spike density. The main objective was t o analyse the diversity and distribution of these traits on the basis of administrative regions and altitudinal gradients. The Shannon-Weave r Diversity Index (H') was used to estimate the magnitude of diversity . With the exception of spike density, all characters were polymorphic in all regions and most altitude groups. However, clinal patterns wer e observed in only a few cases. At the population level, the mean H' v aried from completely monomorphic (H' = 0.00) to highly polymorphic (H ' = 0.80 +/- 0.07). The highest diversity was found in regions with re latively better climatic conditions and in optimal altitude ranges. On country basis, seed colour (H' = 0.98) and spike density (H' = 0.43) displayed the highest and the lowest diversity indices, respectively. Spike density was the only character that exhibited significant differ ences (P < 0.01) both ''between regions'' and ''between altitude group s''. Across characters, most of the variance was due to the lowest hie rarchy, the ''within-population'' component. The ''between region'' an d ''between altitude group'' variances were significant, but spike den sity alone was responsible for the differences. The overall mean H' fo r Ethiopia was 0.77 +/- 0.09 and did not seem to have reduced apprecia bly within the past 25 years or so, when compared to previous estimate s.