Evaluation of Lucerne Cultivars of Two Winter Activity Classes in Contrasting Pedo-Climatic Mediterranean Environments

Lucerne (Medicago sativa L.) forage production may be shifting towards the autumn-spring season, or in cooler environments, due to warmer and drier summers in Mediterranean Europe. This study aimed to evaluate the performance of lucerne cultivars with varying winter activity ratings (WAR) and hardiness in divergent environments of Greece: a cool highland versus a warm lowland. Highlywinter-active (HWA) cultivars were compared to semi-winter-active (SWA) ones for dry matter (DM) yield, seasonal harvest ratios, quality, and agronomic parameters. The SWA cultivars exhibited twice as many overwintered plants and higher summer yields, and were more productive (by 10.4%) in the cooler site. Conversely, HWA cultivars showed enhanced autumn yields and greater productivity (by 10.5%) in the warmer site. Notably, stability analyses revealed trade-offs between productivity and stability, with the most stable cultivar showing lower productivity (by 5.3-5.5%). Additionally, SWA cultivars exhibited higher crude protein content. Plant height and node number correlated with yields in the cool site but not in the warm, underscoring their effectiveness as indirect indicators in marginal environments. Outstanding temperature-specific cultivar responses fully justify the negative relation between winter activity and hardiness regarding productivity. This emphasizes the importance of matching cultivar winter activity and hardiness with specific microenvironments. Region-specific early screening could target the decoupling of the association between low winter activity and increased hardiness, enabling the optimization of cultivars for both traits, while interregional advanced line testing could capitalize on stability and resilience to address the challenges of climate change.