Phenotypic diversity of Tunisian durum wheat landraces

Tunisia is considered as a diversification centre of durum wheat ( Triticum durum Desf.) and barely ( Hordeum vulgare ). It is characterised by large genetic diversity; however, several genotypes are in the process of disappearance. The safeguard and rehabilitatation of this genetic inheritance requires genetic characterisation, evaluation and in-situ and ex-situ conservation. In this context, a local collection of thirty durum wheat accessions was evaluated using agronomical traits. Three other phenological traits: days to maturity, days to heading and filling period were evaluated. The phenotypic diversity was determined by the Shannon-Weaver diversity Index (H') revealing that number of kernel/spike (H'=0.91), yield (H'=0.89), plant height (H'=0.87) and thousand kernel weight (H'=0.86) had the highest diversity index. Flag leaf area (H'=0.32) showed the weakest index. This germplasm presented average diversity (0.77) showing a large genetic variability. Correlations between traits showed a significant positive relation between yield and spikeless tillers/plant (0.90), thousand kernel weight (0.39), plant height (0.35) and flag leaf area (0.36), suggesting the usefulness of these parameter for selecting for improving grain yield. The components analysis explained 59.61% of total variability and led to identification of a group of accessions Jeneh kotifa 1, Jeneh kotifa 2, Jeneh kotifa 3, Sbei glabre, Hamira 1, Hamira 2, Biskri glabre, Mahmoudi, Biskri glabre AP2, Swabaa Elgia, Sbei, and Mahmoudi glabre showing the best agronomical characteristics. These genotypes can, therefore, be used as parents for the improvement of durum wheat.La Tunisie est un centre de diversité génétique du blé dur ( Triticum durum Desf.) et de l'orge ( Hordeum vulgare ). En dépit de la large diversité génétique au niveau du germoplasme local, plusieurs génotypes sont en voie de disparition. La sauvegarde et la réhabilitation de ce patrimoine génétique nécessitent sa caractérisation, son évaluation ainsi que sa conservation in situ et ex situ. Dans ce contexte une collection locale de trente genotypes de blé dur a été évaluée utilisant des paramètres agronomiques. Trois autres paramètres phénologiques à savoir jours de maturation, jours de rétablissement et période de remplissage étaient aussi évaluées. La diversité phénotypique determinée par l'index de diversité de Shannon-Weaver (H') a révélé que le nombre de grains par épi (H'=0.91), rendement (H'=0.89), hauteur des plants (H'=0.87) et le poids de 1000 grains (H'=0.86) avaient un index de diversité le plus élevé. La surface foliare (H'=0.32) a montré un index le plus faible. Ce germplasm presentait un index de diversité moyen de 0.77 montrant ainsi une large variabilité génétique. Les corrélations entre les paramètres a montré une relation positive significative entre le rendement et le nombre de talles d'épillets par plant (0.39), le poids de 1000 grains (0.35) et la surface foliaire (0.36), suggérant ainsi l'utilité de ces paramètres de sélection pour l'amélioration du rendement en grains. L'analyse des composants a expliqué 59.61% de la variabilité totale et a conduit à identifier un groupe de genotypes entre autre kotifa 2, Jeneh kotifa 3, Sbei glabre, Hamira 1, Hamira 2, Biskri glabre, Mahmoudi, Biskri glabre AP2, Swabaa Elgia, Sbei, Mahmoudi glabre montrant les meilleures caractéristiques agronomiques. Ces génotypes peuvent donc être utilisés comme parents pour l'amélioration de blé dur

Genetic variation of salt-stressed durum wheat (Triticum turgidum subsp. durum Desf.) genotypes under field conditions and gynogenetic capacity

Agriculture has new challenges against the climate change: the preservation of genetic resources and the rapid creation of new varieties better adapted to abiotic stress, specially salinity. In this context, the agronomic performance of 25 durum wheat (Triticum turgidum subsp. durum Desf.) genotypes (nineteen landraces and six improved varieties), cultivated in two semi-arid regions in the center area of Tunisia, were assessed. These sites (Echbika, 2.2 g l−1; Barrouta, 4.2 g l−1) differ by their degree of salinity of the water irrigation. The results showed that most of the agronomic traits (e.g. spike per meter square, thousand kernels weight and grain yield) were reduced by salinity. Durum wheat landraces, Mahmoudi and Hmira, and improved varieties, Maali and Om Rabia showed the widest adaptability to different quality of irrigation water. Genotypes including Jneh Kotifa and Arbi were estimated as stable genotypes under adverse conditions. Thereafter, salt-tolerant (Hmira and Jneh Khotifa) and the most cultivated high-yielding (Karim, Razzak and Khiar) genotypes were tested for their gynogenetic ability to obtain haploids and doubled haploid lines. Genotypes with good induction capacity had not necessarily a good capacity of regeneration of haploid plantlets. In our conditions, Hmira and Khiar exhibited the best gynogenetic ability (3.1% and 2.9% of haploid plantlets, respectively). Keywords: Durum wheat, Genetic variation, Salinity, In vitro gynogenesi