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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.

Durum wheat is the most widely grown cereal in Tunisia, but its production is threatened by drought, which is exacerbated by climate change. This study aimed to identify drought-tolerant durum wheat genotypes from five modern varieties and six landraces in a multi-environment trial at two sites (Kef and Siliana, Tunisia) during three growing seasons under rainfed and irrigated conditions. Six drought tolerance indices (mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), tolerance index (TOL), stress tolerance index (STI), and yield stability index (YSI)) were used to evaluate the 11 genotypes. The environment was the dominant source of variation for grain yield (GY; 94.27%), followed by the environment × genotype interaction (4.06%) and genotype (1.65%). Cluster analysis based on GY identified four environment-based groups with distinct water treatments, extreme minimum/maximum temperatures, and rainfall. Principal component analysis and a correlation matrix revealed that drought tolerance indices significantly correlated with GY in non-stressed and stressed conditions and could be separated into four groups. Based on STI, MP, and GMP, G6 and G8 (landraces) were the most drought-tolerant genotypes attaining high GY in both conditions. TOL was able to discriminate G1, G3, and G5 (modern varieties) as well as drought-susceptible genotypes, all of which were suitable for irrigation. Genotypes G7, G9, G10, and G11 (landraces), which had high SSI and lowest STI, MP, GMP, and YSI values, were susceptible to drought and were thus not suitable for cultivation in both conditions. Finally, G2 and G4 (modern varieties), which had an intermediate rank for different indices, were classified as semi-tolerant or sensitive genotypes. Drought tolerance indices and genotype ranks were helpful tools to screen drought-tolerant genotypes with a large adaptation to a range of environments, namely irrigated and rainfed conditions (landraces G6 and G8), or genotypes with the ability to adapt (modern varieties G1, G3, and G5) to irrigated conditions.