Degree of seed desiccation sensitivity of the Amazonian palm Oenocarpus bacaba depends on the criterion for germination

Abstract

Across the seed-seedling transition, several germination criteria are used in studies of palm-seed germination. In Oenocarpus bataua, these criteria have differential tolerance to thermal stress. In this study, we evaluated the tolerance of germination criteria to seed desiccation of the congeneric Oenocarpus bacaba. We dried seeds to different moisture contents (MC) before scoring first cataphyll, second cataphyll, enclosed eophyll and expanded eophyll. Seeds without drying had 41.7% MC. Germination success reached close to 70% after 75 and 105 days, depending on the germination criterion. Safe MC was close to initial MC and all seeds were dead with MC < 26.7%. As the primordial organs of the cataphylls and the eophyll are already detectable in the palm-seed embryo, all were affected by drying. Critical MC, defined here as 50% loss of germination capacity, increased from 35.4% (first cataphyll) to 37.1% (expanded eophyll) and confirmed that, across the seed-seedling transition, more advanced germination stages had a higher sensitivity to desiccation. During germination and development, the criteria appear in sequence over several weeks. Consequently, the desiccation damage was only detectable when the last criterion was evaluated. To avoid an underestimation of damages, we suggest that seed-stress studies in palms should take into account an adequate period for seedling development, which, for O. bacaba, was 105 days until the expansion of the eophyll.

Desiccation, storage and physiological quality of Phoenix roebelenii O’Brien (Arecaceae) seeds

“…However, at 26.7%, they showed 100% mortality. These authors also reported that, in more developed seedlings, plant organogenesis, such as eophyll and cataphyll, is impaired (2). In this context, seed high water content during storage can favor deterioration processes by increasing respiration, followed by membrane degradation, microorganisms proliferation, and reduced germination and vigor (1,4) Desiccation tolerance can be defined as seed capability to maintain viability after losing cell water content without presenting irreversible damages (14,22).…”

Water immersion and one-year storage influence the germination of the pyrenes of Copernicia alba Morong, a palm tree from a neotropical wetland

“…Studies have shown that ex-situ conservation of palm seeds are associated with loss of seed viability over time (Broschat 1994, Orozco-Segovia et al 2003, Nascimento et al 2010, Jacob & Decruse 2015, Oliveira et al 2015, Felix et al 2017, Beltrame et al 2018, Bastos et al 2021. Several external factors influence the viability of tropical palm seeds during storage, such as temperature and time, and intrinsic factors like seed moisture content, seed maturation, and desiccation sensitivity (recalcitrance) (Roberts 1973, Orozco-Segovia et al 2003, Baskin & Baskin, 2014, Sano et al 2015.…”