Root System Architecture and Its Association with Yield under Different Water Regimes in Durum Wheat

Durum wheat (Triticum durum Desf.) is a major cereal crop grown globally, but its production is often hindered by droughts. Breeding for adapted root system architecture should provide a strategic solution for better capturing moisture. The aim of this research was to adapt low-cost and high-throughput methods for phenotyping root architecture and exploring the genetic variability among 25 durum genotypes. Two protocols were used: the "clear pot" for seminal root and the "pasta strainer" to evaluate mature roots. Analysis of variance revealed significant segregation for all measured traits with strong genetic control. Shallow and deep root classes were determined with different methods and then tested in yield trials at five locations with different water regimes. Simple trait measurements did not correlate to any of the traits consistently across field sites. Multitrait classification instead identified significant superiority of deep-rooted genotypes with 16 to 35% larger grains in environments with limited moisture, but 9 to 24% inferior in the drip irrigated site. Combined multitrait classification identified a 28 to 42% advantage in grain yield for the class with deeper roots at two environments where moisture was limited. Further discrimination revealed that yield advantage of 37 to 38% under low moisture could be achieved by the deepest root types, but that it also caused a 20 to 40% yield penalty in moisture-rich environments compared with the shallowest root types. In conclusion, the proposed methodologies enable low-cost and quick characterization of root behavior in durum wheat with significant distinction of agronomic performance.