Resistencia y resiliencia a la sequía en gramíneas forrajeras perennes c3 y c4

Native grasslands are an important source of biodiversity as well as the main forage basis for meat production in Uruguay. Within a context of increasing climatic variability, it is important to promote species capable of adapting to these conditions. An experiment was carried out under controlled conditions in a glass greenhouse, which began on 7^th January 2021 and ended on 1^st May 2021 at INIA Tacuarembó, Uruguay. The objective was to evaluate the drought resistance and post-drought resilience capacity in both native and exotic species: with C3 (Bromus auleticus, Festuca arundinacea) and C4 metabolisms (Andropogon lateralis, Paspalum dilatatum, Paspalum notatum). A completely randomised design was used with 6 treatment per species, where each of them was associated with a certain soil water availability (5, 10, 30, 50, 75, 90 % of SWA) and 4 replicates per treatment. The experiment was divided into two phases: Phase I of drought resistance, in which plants were exposed to the different SWA levels, and Phase II of drought resilience, in which all treatments were exposed to the same level of SWA (75%). Total biomass, green forage, N and crude protein (CP) contents, water consumption in both phases, daily evapotranspiration (ET) during the drought resistance phase and tillers´ survival at the end of the experiment were quantified. The most drought resistant species were P. dilatatum and P. notatum, followed by B. auleticus, while the least resistant were F. arundinacea and A. lateralis, measured both in biomass production and green forage. Under low SWA, CP content mas greater in all species except for P. notatum, which did not vary with different AD levels. The most drought resilient species was P. notatum. Greatest ET was observed in F. arundinacea, followed by B. auleticus; however, the latter was less efficient in water consumption per forage production unit. C4 species presented the least values for both variables.