Effect of Rainfall Reduction and Competition on the Phenology of the Mediterranean Forage Perennial Legume Bituminaria bituminosa var. albomarginata cv. Lanza

Abstract

Tedera (Bituminaria bituminosa (L.) C.H. Stirt.) is a Mediterranean drought-tolerant species that shows potential as a forage perennial legume for Mediterranean livestock systems. This three-year study investigated the phenology of the newly developed variety of tedera (Lanza) in response to an annual 24% rainfall reduction and competition compared to alfalfa (Medicago sativa L.) in a typical Mediterranean environment of the Iberian Peninsula. Tedera showed early phenology for the reproductive stages from inflorescence emergence to ripening compared to alfalfa, with a long flowering period from early April to mid-May, overlapping with mature fruits. In general, tedera responded to a 24% reduction in rainfall with earlier inflorescence emergence and flowering, demonstrating plasticity to drier conditions. Competition affected the phenology through delayed start of inflorescence emergence and flowering, and especially by reducing the probability of plants reaching reproductive stages. Tedera exhibited overall later leaf shedding than alfalfa and even retained green leaves throughout the summer of the establishment year, whereas alfalfa shed its leaves in July. Low cold tolerance and competition from weeds affect the phenology of tedera and may limit its persistence. Further research and breeding efforts are needed to define suitable management strategies and ensure the provision of green forage during the summer season by this species, which may play a crucial strategic role in facing future, more arid scenarios in Mediterranean livestock systems.