Germination requirements of two sheep-preferred grasses (Hordeum comosum and Koeleria vurilochensis var. patagonica) from semiarid Patagonian steppes

Abstract

Grazing by domestic exotic herbivores on native vegetation in Patagonian steppes has led to the deterioration of forage resources, where grasses are replaced by shrubs, and preferred grasses by non-preferred ones. Therefore, attempts at breeding and regeneration should start by identifying species with potential forage capability. Two perennial high-preferred species are the focus of this paper: Hordeum comosum and Koeleria vurilochensis. For the first time, we studied their morphological traits, dormancy level, and their temperature and water germination requirements, through thermal- and hydrotime models. H. comosum seeds were solid, large and heavy, while K. vurilochensis seeds were soft, small and light. Neither light-quality nor alternating temperature affected the dormancy level in seeds of both species. Seeds of H. comosum and K. vurilochensis required, respectively, 768.74 °Ch and 2217.89 °Ch to germinate; alternatively, base temperature was higher for H. comosum than for K. vurilochensis. The hydrotime required by H. comosum was 26 MPah and 110 Mpah for K. vurilochensis but, base water potential was −0.99 MPa and −1.45 MPa, respectively. For all the conditions, H. comosum displayed a higher germination rate compared to K. vurilochensis seeds. Deeper knowledge on the morphological and germination traits of seeds is a key step toward breeding and restoration of forage potential species.