The impact of agricultural intensification on legume seeds with physical dormancy in sustainable farming systems. A review

Abstract Physical dormancy in seeds is caused by a water-impermeable seed coat. It plays a crucial role in the sustainability of ley farming systems in Mediterranean climates by enabling pasture legumes to regenerate from a soil seed bank. Sophisticated management of the pattern of physical dormancy break can synchronize germination of plants with the optimal growing season, essential to the sustainability of the system. The ability of the maternal plant to reproduce and provide its progeny (seed) with sufficient resources is influenced by both genetic and environmental factors. However, when abiotic (e.g., drought, temperature) or biotic (e.g., pests, diseases) stressors affect the maternal plant during its reproductive phase, the allocation of resources to seeds can vary, leading to variability in physical dormancy outcomes. This genetic × environment interaction is well documented; however, a third factor, management, is less understood. Herein lies a significant knowledge gap, and this is the first review that examines physical dormancy from an agricultural management perspective. In the manuscript, we explore the evolution of physical dormancy in pasture legumes in ley farming systems and how the intensification of agricultural management practices inadvertently affects physical dormancy development and the pattern of release. This intensification threatens the sustainability of ley farming by changing the timing of physical dormancy release, which concomitantly occurs under changed climatic conditions. Therefore, climate change combined with the intensification of agricultural management practices, including pesticide use, altered grazing regimes, and frequency of crop rotation, poses significant challenges to physical dormancy regulation and soil seed bank dynamics in ley farming. We suggest that to combat the impacts of agricultural intensification, detailed studies and breeding programs should focus on selecting legumes with both agricultural and climatic resilience for successful adaptation to evolving agricultural landscapes and ensure continued sustainable productivity.