Abstract
In Mediterranean regions, the performance of durum wheat (Triticum turgidum L. var. durum Desf.) yield often varies due to significant genotype × environment interaction (GEI); therefore, yield stability is an important consideration in breeding programs. The aim of this research was to explore the GEI pattern and yield stability of 24 promising durum wheat lines, selected by ICARDA in several African countries (seven elites, four commercial varieties, and 13 durum wheat wide crosses, generated by hybridization of elites and Triticum dicoccoides Koern. ex Schweinf., Triticum araraticum Jakubz, and Aegilops speltoides Tausch) against a Tunisian local check variety ‘Salim’. Yield assessment was conducted across six environments under rainfed conditions, at the field station of Kef in a semi-arid region during four cropping seasons (2014–2015, 2015–2016, 2016–2017, and 2017–2018) and in a sub-humid region at the station of Beja during two cropping seasons (2015–2016 and 2018–2019). The analysis of variance showed that the environment is the main source of variation of grain yield (72.05%), followed by the interaction environments × genotypes (25.33%) and genotypes (2.62%). The genotype × genotype by environment model (PC) based on grain yield identified a mega-environment including Kef (2016–2017 and 2017–2018) and Beja (2015–2016 and 2018–2019) and elite line 22 as a widely adapted genotype. Combined analysis, computed using the average grain yield of lines and the yield stability wide adaptation index (AWAI), showed that elite lines 9 and 23 (2.41 and 2.34 t·ha−1, respectively), and wild relative-derived lines, 5, 1, and 10 (2.37, 2.31, and 2.28 t·ha−1, respectively) were more stable and better yielding than the national reference (2.21 t·ha−1). This finding supports the good yield potential of wild relative-derived lines. The five selections are recommended to be developed in multi-environments in several regions of Tunisia, especially in semi-arid area.
Highlights
The analysis of variance (ANOVA) for grain yield (GY) of the 25 genotypes tested over six environments revealed that the effect of environments (E), genotypes (G), and genotype × environment interactions (GEI) were significant (p < 0.01) for this attribute (Table 4)
A high heritability for GY was found over all environments with values ranging from 0.68 (Beja_19)
The results indicate that these genotypes responded differently to the environments, thereby confirming the phenotypic diversity among the assessed genotypes
Summary
The Mediterranean countries account for the largest production area of durum wheat, and North Africa represents the largest import market [3]. In these regions, the appreciation for durum wheat has a long history and is associated with many traditional foods [4], such as pasta and couscous, in addition to a number of other semolina products, such as frike, bourghul, and unleavened breads. The great selection pressure imposed on breeding programs has induced a genetic base narrowing of the wheat germplasm [8] This loss of diversity has caused a reduction in allelic plasticity, leading to a germplasm that is less adapted to climate change [9]
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