干旱区生态环境知识资源中心

Asteraceae is the most diverse family of vascular plants in the world and the most numerous in Argentina, with 26% of endemic species. Many Asteraceae are pioneer species facilitating the establishment of other species, and several have been employed in restoration. Knowing the characteristics of seeds and their germination is crucial to employ them in restoration projects; hence this study explored basic physiological aspects of the germination of Gutierrezia solbrigii Cabrera and Senecio subulatus D. Don ex Hook. & Arn. var. erectus Hook. & Arn., two endemic shrubs of Argentina, distributed in arid Patagonia. Seeds came from the Reserva Provincial Auca Mahuida (NE of NeuquEn Province), in the Phytogeografical District of Payunia (ecotone between Monte and Steppe). Hydrocarbon extraction activities in the reserve have originated degraded areas where these species could be employed with revegetation purposes. We evaluated germination percentage (G), time until germination (IG) and mean germination time (TMG) of control seeds and seeds subjected to pre-germinative treatments: cold moist stratification for 15 days (EHF15), mechanical scarification with sand and sandpaper (EML) for both species, and cold moist stratification for 30 days (EHF30) and mechanical scarification with a scalpel (EMB) for S. subulatus. In all treatments, germination percentage was high (G. solbrigii: 77% EHF15; 81% EML; S. subulatus: 88% EHF15, 89% EHF30, 84% EML, 94% EMB) and similar to controls (G. solbrigii: 82%, S. subulatus: 88%). Differences were detected only between EMB and EML for S. subulatus: G and IG were higher in EMB and lower in TGM, probably because seeds were not homogenously scarified with EML. In conclusion, the studied species lack dormancy mechanisms under the experimental conditions, and since they are also endemic and grow in disturbed environments, they are excellent candidates to be used in restoration projects.