BIODIVERSITAS ISSN: 1412-033X Volume 22, Number 2, February 2021 E-ISSN: 2085-4722 Pages: 1025-1036 DOI: 10.13057/biodiv/d220259 Assessment of biological and agronomic diversity of seven durum wheat varieties cultivated in the Northeastern region of Algeria NABIL BOUDERSA 1,♥ , GHANIA CHAIB 1 , AICHA ATOUI 1 , RADIA CHERFIA 2 , HANANE BOUDERBANE 1 , LEILA BOUDOUR 1 1 Laboratory of the Development and Valorization of Plant Genetic Resources, Department of Biology and Plant Ecology, Frères Mentouri University. Constantine1, Route de Ain El Bey, Constantine 25017, Algeria. Tel. +213-671977482, ♥ email: nabil.boudersa@student.umc.edu.dz 2 Laboratory of Mycology, Biotechnology and Microbial Activity, Department of Applied Biology, Faculty of Nature and Life Sciences, Frères Mentouri University. Constantine1, BP, 325 Route de Ain El Bey, Constantine 25017, Algeria Manuscript received: 30 November 2020. Revision accepted: 25 January 2021. Abstract. Boudersa N, Chaib G, Atoui A, Cherfia R, Bouderbane H, Boudour L. 2021. Assessment of biological and agronomic diversity of seven durum wheat varieties cultivated in the Northeastern region of Algeria. Biodiversitas 22: 1025-1036. The present work was carried out during the 2017/2018 agricultural season, at the experimental station of the ‘Institut Technique des Gra ndes Cultures’ (ITGC) – El Khroub, Constantine, Algeria. The main objective of this study was the evaluation and the characterization of seven varieties of durum wheat (Triticum durum Desf.) in terms of their behavior and yield. For these reasons, several phenological, morpho-physiological, and biochemical traits, as well as the yield with its components were studied. The obtained results showed a significant variety effect, in particular, for the variables corresponding to the production and to the tolerance. The analysis of the correlation coefficients indicated that the number of spikes per m 2 , the number of grains spike -1 , and the rate of chlorophyll pigments in the leaves were the most related characteristics to grain yield. Indirect selection for breeding productivity through these traits could prove to be effective. Besides, it revealed that tall varieties displayed better resistance to possible hazards; had high relative water content (RWC), accumulated more soluble sugars and proline, as well as, they showed a low level of Malondialdehyde (MDA) compared to other varieties. In addition, this study allowed us to determine many relationships between the studied parameters, that can make a contribution in both the productivity and the adaptation improvement programs of the durum wheat. Keywords: Characterization, correlation, diversity, productivity and adaptability, Triticum durum INTRODUCTION Triticum durum Desf. is one of the most essential cereals that are cultivated worldwide on almost 17 million hectares (ha), with a global production of 38.1 million tonnes in 2019 (Xynias et al. 2020). In Algeria, durum wheat is the first cultivated cereal; it occupies 45% of the area designated for cereals, or 1.6 Mha (ONFA 2017). However, its production is still insignificant, it covers only 20 to 25% of the needs of an increasingly growing population, and the rest being imported (Chehili et al. 2017). This low production is often explained by the fact that the majority of the area sown to durum wheat is located on the high plains, where the rainfall and the temperatures are subjected to large intra and inter-annual variations, often combined with frequent spring frosts and the appearance of sirocco at the grain filling stage; which seriously affect the yields (Benniou et al. 2018). Indeed, this situation can only be unblocked by a real and an effective increase in yields through the application of better management of both adapted technical pathways (soil preparation, date and dose of sowing, irrigation, fertilization, weed control, and disease control), and genetic improvement allowing to create adapted varieties to environmental conditions of cultivation. The goal of genetic improvement in wheat has always been to increase productivity. Whereby, the success of this strategy is linked to the existence of favorable environmental conditions, which allow the expression of the different factors of the yield (Ghennai et al. 2017). For this reason, the study and the characterization of genetic resources to create new varieties with good quality, high yield, adapted to climatic variations, and resistance to diseases are essential (Amallah et al. 2016). Besides, these steps also make it possible to estimate the existing diversity in the studied material, and they are considered as a starting point for their use in breeding programs (Khennaoui 2018). Thus, this research requires studying, identifying, and verifying the phenological, morpho-physiological, and biochemical characteristics related to the yield. Therefore, a good understanding of all of these aspects during the life cycle of the plant and a well comprehension of the main links between the grain yield and these components can be useful in the identification and the selection of the interest traits. Indeed, several agricultural studies have confirmed that this information is used to guide the selection process in order to improve the characteristics capable of obtaining better performance (Aghaee et al. 2010; Zarkti et al. 2012; Sahri et al. 2014). The current study had two main objectives : (i) Evaluation of the variability of seven varieties of durum wheat, using measurements of agro-morpho-physiological and biochemical characters. (ii) Analyzing and highlighting the different links recorded between the studied parameters