Tolerância à dessecação e armazenamento de sementes de Myrcianthes pungens (O. Berg) D. Legrand (Myrtaceae)

Abstract

RESUMO Muitas barreiras são encontradas na produção de plântulas de espécies nativas dos trópicos, em grande parte devido ao desconhecimento de suas sementes. Entre elas, a falta de tecnologia para armazenamento prolongado de sementes recalcitrantes, que também pode ser um grande risco para a perda de importante diversidade vegetal. Neste trabalho, analisamos a tolerância à dessecação e a capacidade de armazenamento de sementes recalcitrantes de Myrcianthes pungens (O. Berg) D. Legrand. Os resultados mostraram que as sementes de M. pungens são intolerantes à dessecação de até 30% de água, são melhor armazenadas em baixas temperaturas e, sob altas temperaturas apresentam altas taxas de respiração e outros processos oxidativos.

Respiratory rates and freezing tolerance of embryos of Inga vera Willd. subsp. affinis (DC.) T.D. Penn. from different regions

“…Thus, one cannot consider storing I. vera embryos merely by lowering the temperature and expecting metabolism to stop: they will continue to respire. As shown in previous studies (Araujo and Barbedo, 2017;Bonjovani and Barbedo, 2019;Guardia et al, 2020), there were no patterns of change in respiration with reduction of water content for most embryos from different regions. This result differs from the outcomes for desiccation-tolerant seeds in general, or even for some desiccation-sensitive seeds, such as Castanea sativa (Leprince et al, 1999) and Eugenia pyriformis (Lamarca et al, 2020).…”

“…The germination test was carried out on a paper roll, in BOD chambers, model 347 CD (Fanem, São Paulo), at 25 °C and continuous light. The evaluations were performed every two days for 36 days; data was recorded on the number of embryos that emitted primary roots (to calculate germination) and those that produced normal seedlings, and average germination time was calculated (Santana and Ranal, 2004;Guardia et al, 2020). The first primary root emitted was considered as germination; only one primary root unit was counted, since there was no occurrence of polyembryony.…”

Evolution and taxonomic meaning of seed fatty acid profiles of Campomanesia (Myrtaceae)

“…4.A, B), may have consequences in aspects of seed physiology. High levels of unsaturated FA may increase the tolerance of cell membranes to low water potentials (Uemura and Steponkus 1994;Uemura et al, 1995).Similar patterns of FA pro les, with high concentrations of saturated FA, are observed in species of Myrteae with recalcitrant (intolerant to desiccation) seeds, such as Myrcianthes pungens(Guardia et al, 2020) and Eugenia uni ora (Delgado and Barbedo, 2012), the former with 31% and the latter with 45% of saturated FA(Andrade et al, 2012). Instead, orthodox (tolerant to desiccation) seeds of Myrtus communis(Franchi et al, 2011) exhibit high concentrations (86%) of unsaturated FA (Wannes and Marzouk, 2016).…”

Challenges for Storing Recalcitrant Seeds

“…Despite being grouped under the same name, recalcitrant seeds present different behaviors regarding the degree of recalcitrance, since they have variable tolerance to desiccation and storage time, among different species and even within the same species (Guardia et al, 2020).…”