Water scarcity in arid and semi-arid regions limits the sustainability of livestock systems, making it necessary to evaluate forage crops with greater water use efficiency. Lotus corniculatus L. has emerged as an alternative due to its nutritional value and tolerance to environmental stress conditions. The objective of this study was to evaluate the agronomic performance of five ecotypes and one variety of L. corniculatus grown under optimal soil moisture content (OSMC) and suboptimal soil moisture content (SSMC) conditions in open fields in Northern Mexico. During spring and under SSMC, ecotype 255301, and the Estanzuela Ganador (EG) variety showed significantly higher values in stem length and number; likewise, EG registered the highest leaf area index (LAI) under OSMC. In summer, ecotypes 255305 and 255301 showed the best performance in stem length and rhizome crown diameter (RCD) under OSMC, while EG stood out in LAI. Fresh biomass production per rhizome (FBPR) in spring showed slight variations among the genetic materials under OSMC, while under SSMC, EG, and ecotype 255301 recorded the highest FBPR values (577.3 and 547.6 g, respectively). In summer and under OSMC, ecotype 255301 and EG maintained the highest FBPR (321.6 and 303.5 g, respectively), while ecotype 255301 showed the highest productivity (333.6 g) under SSMC.