Festuca pallescens: a promising native forage grass under incipient domestication in Patagonia

MARCHELLI, P.; NAGAHAMA NICOLÁS; ALEJANDRO APARICIO; ALDANA LÓPEZ; VERÓNICA GUIDALEVICH; UGARTE CRISTINA; MARÍA MARTA AZPILICUETA; JUAN PABLO ANGELI

Córdoba

Simposio; First Plant Breeding Symposium; 2021

Instituto Nacional de Tecnología Agropecuaria (INTA)

The environmental heterogeneity, historical overgrazing, and current impacts of global change, impose strong selection pressures on native Patagonian grasslands. Particularly at arid and semi-arid regions, grasslands have a relatively low productivity, limiting the stocking rate. This promotes the overuse of lands and its consequent degradation. These natural grasslands are the main forage resource for sheep cattle (central productive activity of the region) and are largely dominated by grasses where Festuca pallescens (St. Yves) Parodi is a key species, with a wide distribution range and an outstanding participation in the diet of cattle. In recent years, studies revealed a decline in the grasslands of this species, which can be compounded by climate change predictions. Therefore, there is an interest in its domestication and breeding, as well as in the search for genotypes adapted to unfavorable or extreme environments to increase grassland productivity, mitigate degradation and promote their restoration. We combined field and nursery trials, both under optimal and stressful conditions, with genotyping at molecular markers to study the main characteristics of this native species along its whole natural distribution. Morphological and phenological traits evaluated in provenance and progeny trials showed variability among populations in growth characters (height, tussock shape, biomass, tillering) and phenological traits (flowering, fructification, seed production). To disentangle selection effects we compared the differentiation at these quantitative traits (Pst) with genetic differentiation at neutral microsatellite markers (Fst) observing divergent selection for traits related with tussock shape. In addition, populations under drought stress in controlled experiments, showed differential responses: origins from more arid environments having a better ability to use pulses of water. These populations resulted particularly relevant due to their tolerance to drought, but also for their molecular distinctiveness evidencing possible events of hybridization with other sympatric species (e.g. Festuca argentina, F. gracillima). Also, the species proved to behave well in productive systems. We evaluated survival and biomass production (forage) by sowing in two sites outside its natural distribution range with watering, and we observed a good recruitment (60% emergency), with a biomass production of 400 gr/m2 after two years in the field. Altogether, the information obtained for the moment highlights a great variation in this species, with populations from arid environments outstanding as more tolerant to harsh conditions. The high variation found, gives a good base for selection of promising genotypes. Moreover, some genotypes or populations proved to be promising for restoration proposes. In order to be able to grow the species in harsh environments without watering, best seeding conditions must be established. Ongoing studies focus on determining heritability of the most relevant traits for further selection and the exploration of new technologies to establish the species in extreme arid environments.