DISTRIBUTION AND PHENOTYPIC VARIABILITY ASPECTS OF SOME QUANTITATIVE TRAITS AMONG DURUM WHEAT A CCESSIONS

A durum wheat (Triticum durum Desf.) collection with 111 accessions represents a large part of the collection of Triticeae species in Tunisia were evaluated for six qualitative traits: seed colour, seed size, glume colour, glume pubescence, spike density and beak length. Distribution of traits showed that this germoplasm was dominated by dense spike, white and glabre glume, long beak, brown and large grain. Phenotypic diversity is determined by the index Shannon-Weaver (H’). This index calculated for each parameter revealed that spike density (H’ =0.86), glume pubescence (H’ =0.80) and glume colour (H’ =0.79) showed the best diversity index. Seed size showed the weakest index (H’ =0.69) which indicated a low phenotypic variability for this parameter. This durum wheat germoplasm presented an average of diversity index about 0.77, showing a large diversity of this collection. These values showed that the germoplasm has a relatively important diversity, confirming that Tunisia is one of the principal durum wheat secondary centres of diversification. This genetic diversity can be exploited in improvement programmes.