TRATAMENTOS PARA A SUPERAÇÃO DE DORMÊNCIA EM SEMENTES DE Brachiaria humidicola (Rendle) Schweick

Abstract

Villas Bôas 4 INTRODUÇÃO O Brasil é o maior produtor, consumidor e exportador de sementes de espécies forrageiras tropicais, com produção estimada de 70 mil toneladas, na safra 2008/2009 (Abrasem 2010), já tendo alcançado produções superiores a 100 mil toneladas, em safras anteriores. Mais de 80% do mercado é dominado por cultivares do gênero Brachiaria, cuja introdução ABSTRACT RESUMO na formação de pastagens, no Cerrado, resultou em ganhos significativos nos índices de produtividade de carne, devido ao rápido aumento da capacidade de suporte das pastagens. Isto ocorreu devido à ampla adaptação das espécies às condições edafoclimáticas da região, sobretudo aos solos ácidos e de baixa fertilidade predominantes nos trópicos (Rao et al. 1996). Brachiaria humidicola (Rendle) Schweick apresenta maior tolerância a solos pouco drenados,

Physiological and sanitary quality, and transmission of fungi associated with Brachiaria brizantha (Hochst. ex. A. Rich.) Stapf seeds submitted to thermal and chemical treatments

“…Means followed by the same lowercase letter on the line, and capitalized on the column; do not differ statistically by the Tukey's test at 5% probability. Costa et al (2011) found that storage for 21 months was more effective for overcoming B. humidicola seed dormancy than acid scarification or germination promoting substances *There was no interaction between harvests and treatments for this variable. Means followed by the same lowercase letter on the line, and capitalized on the column; do not differ statistically by the Tukey's test at 5% probability.…”

“…application. However, seeds stored for periods longer than 12 months may have lower quality and treatments with sulfuric acid does not promote germination increase, as evidenced by Custódio et al (2012), in B. brizantha seeds lots. Paniago et al (2014) found that the storage time did not provide B. humidicola seed quality increase nor reduced the percentage of dormant seeds.…”

“…It is remarkable the presence of dormancy in freshly harvested seeds in several species of tropical grasses (Usberti and Martins, 2007;Costa et al, 2011), associated to physiological causes and which are progressively removed during storage (Almeida and Silva, 2004). The recommendations described in the Rules for Testing Seeds -RAS (Brasil, 2009), as well as in most studies conducted to break dormancy in seeds of Brachiaria, the use of chemical scarification with sulfuric acid and thermal treatment are mentioned (Almeida and Silva, 2004;Lacerda et al, 2010;Costa et al, 2011;Custódio et al, 2012).…”

Physiological changes in hybrid Brachiaria cv. Mulato II after accelerated aging to overcome dormancy

“…Despite the agronomic advantages, the seeds of this hybrid species, as well as the other Brachiarias, present dormancy (Costa et al, 2011). However, the dormancy mechanism has peculiarities for different species, making it difficult to generalize about its causes, which may occur independently or in combination, as is the case for most seeds of forage grasses (Previero et al, 1998, Santos et al, 2011.…”

Methods for breaking seed dormancy of ryegrass during storage periods

“…However, it is a partially problem for seed production, dormancy soon after harvest makes the evaluation of the physiological quality and the implementation of measures related to quality control of production difficult, which requires appropriate methods to break the dormancy of seeds. Furthermore, it is known that, for many forage species, the effectiveness of methods designed to break dormancy varies depending on the age of the seeds (Costa et al, 2011) and that the storage itself is enough to promote dormancy breaking.…”