Ferruginous Rocky Outcrops have high levels of species richness and endemism, but have been threatened by several anthropic actions, especially mining. Eragrostis polytricha, a common grass species in the vegetation of these outcrops, has shown promising features for use in the recovery of mining areas. However, in order to fully understand the species' potential for such use, its requirements for germination, seed dormancy break and seedling development must be determined. Thus, we aimed to: (1) assess the temperature conditions needed for seeds of E. polytricha to germinate; (2) evaluate the effects of KNO₃ in breaking seed dormancy; and (3) analyze the germination efficiency of seeds that are still in spikelets. The experiment included seven treatments: 15-35 ºC with KNO₃, 20-30 ºC with KNO₃, 15 ºC with KNO₃, 25 ºC with KNO₃, 35 ºC with KNO₃, 20-30 ºC with water, and 20-30 ºC with KNO₃ using spikelets. The treatments with alternating temperatures associated with KNO 3 yielded the highest germination rates, suggesting that these two factors combined can break seed dormancy. Seeds inside spikelets exhibited a high germination percentage, and thus represent an interesting alternative for seedling production.
RESUMO Uma das alternativas para se obter espécies potenciais para a revegetação de áreas degradadas é utilizar as que se desenvolvem a partir do banco de sementes de topsoil e nesse contexto, as gramíneas são as mais indicadas por possuírem características associadas à estabilização do solo. Este estudo objetivou avaliar as espécies nativas desenvolvidas em banco de sementes de topsoil ferruginoso e selecionar as gramíneas de maior índice de valor de importância (IVI), considerando-as espécies em potencial para utilização em programas de revegetação. O topsoil foi depositado na Unidade de Pesquisa e Inovação em Campos Rupestres Ferruginosos da Gerdau, Ouro Branco, MG, Brasil e após a germinação e estabelecimento das plantas, realizou-se estudos fitossociológicos. Eragrostis polytricha Nees apresentou maiores valores não apenas de IVI, mas também de Frequência Relativa e Cobertura Relativa, adicionalmente apresentou o segundo maior valor de Densidade Relativa. Portanto, recomendamos E. polytricha para a utilização em programas de revegetação.
We report new occurrence records of Gymnopogon doellii in Brazil, based on collections from the Ferruginous Campos Rupestres (rocky outcrops) of Minas Gerais state, in the southeastern region of the country. This native grass had been previously reported in Brazil only from Cerrado areas of Minas Gerais and Goiás states and the Federal District. According to the IUCN criteria, the species is endangered. Within the genus, G. doellii is distinguished by having short rhizomes, indistinct leaf blade midveins, ligules with a fringe of hairs and acuminate glumes twice the size of the floret. We provide photographs of individuals in the field, an illustration with details of the species morphology and an updated geographic distribution map.
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