Use of different conditioning agents and quality evaluation of two lots of annatto (<i>Bixa orellana</i>) seeds

Abstract

Devido à baixa germinação de sementes de Bixa orellana L., há a necessidade de se testar diferentes técnicas que viabilizem sua reprodução, como o condicionamento fisiológico. O objetivo do presente trabalho foi caracterizar a germinação de dois lotes de sementes de urucum sob efeito do condicionamento fisiológico. Para isso, sementes de dois lotes (recém-colhido e armazenado) foram submetidas ao condicionamento fisiológico em solução aerada de: 1) água deionizada; 2) água catódica; 3) nitrato de potássio a 0,3%; 4) nitroprussiato de sódio a 100 µM; por 24 e 48h, e um tratamento adicional (controle) sem condicionamento. Após o teste de germinação, as sementes que não germinaram foram submetidas ao teste de tetrazólio a 0,075% a 30 °C, no escuro, durante 24 h. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial (4 x 2 + 1) com quatro repetições de 25 sementes por tratamento. Apesar da baixa germinação já relatada para a espécie, foi possível obter germinação sem nenhum tipo de pré-tratamento como quebra de dormência, mesmo em lote armazenado por 10 anos e com teor de água de 8%. Os agentes condicionantes não foram eficientes no aumento da germinação de sementes de urucum. São necessários novos trabalhos para classificação da espécie quanto ao seu armazenamento.

Effect of long-term storage on viability of buffel grass (Cenchrus ciliaris L.) seeds

“…A fact also observed in annatto seeds (Bixa orellana) stored for more than 10 years. However, in both cases, improvement was observed in the other germination variables when using this salt (Kreuser et al, 2016;Fernandes et al, 2021). The use of KNO 3 is generally indicated for promoting germination and overcoming dormancy in different types of seeds, including forage (Bareke, 2018;Golmohammadzadeh et al, 2020;Ali et al, 2021;Pereira et al, 2021).…”

“…In the 1970s, an Active Germplasm Bank of forage species was implemented in the Caatinga experimental unit of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa Semiárido), including several buffelgrass genotypes, which was the most outstanding among the evaluated species, due to its greater potential for forage production (Oliveira et al, 1999). Based on this, an Active Germplasm Bank was implemented for Cenchrus species and, in 2009, it integrated the National Platform of Genetic Resources, in the Vegetal Genetic Resources Network -Vegetal Network (Embrapa Cenargen, 2009;Jank et al, 2021). The improvement of these plants is essential to obtain information and develop cultivars that present desirable characteristics considering local needs.…”

Overcoming dormancy in seeds of Bixa orellana L.

“…By using the H2O solution, it was possible to observe the low percentage of emergence (Table 1), thus presenting the need to use methods to overcome dormancy as the use of GA3 solution to break seed dormancy and achieve better results in emergence. Despite reports of studies on the low germination of annatto seeds (Lopes et al, 2008;Neto et al, 2018),many authors attribute its low germination to the impermeability of the tegument (Castello et al, 2012;Fernandes et al, 2021;Pereira et al, 2012),to which methods of overcoming dormancy can be assigned to improve seed viability. In this work, the treatment with GA3 solution for a period of 24 hours was efficient to overcome the dormancy imposed by the tegument of the annatto seed (Table 1), being possible in the initial stand test and the emergence velocity index to separate the solutions in levels of distinction with the GA3/0h and H20 solution lower and the GA3/24h higher and presenting a higher percentage of emergence compared with the other solutions, therefore as mentioned by authors due to the tegument constitute a physical barrier hindering the entry of water with the need for methods to overcome dormancy (Amaral et al, 2000;Custódio et al, 2002;Picolotto et al, 2013).Annatto seeds, when submitted to mechanical and sulfuric acid scarification, absorb water satisfactorily, overcoming the dormancy imposed by the tegument, and the use of GA3 also increases the speed of germination (Bocatto & Forti, 2020),thus evidencing the need for methods to overcome the dormancy of annatto seeds.…”