Establishment of post-harvest early-developmental categories for viability maintenance of Araucaria angustifolia seeds

Abstract

Araucaria angustifolia seeds are recalcitrant, and their metabolism remains high during storage. This research aimed to describe the initiation of germination in A. angustifolia seeds during storage in order to standardize the assessment of physiological quality and to promote seed conservation. Seeds were collected from two populations and stored for 270 days in the natural laboratory environment and cold chamber. Seeds were classified according to four early developmental stages: I -mature seeds; II -seeds with elongation along the embryonic axis; III -beginning of root protrusion; IV -advanced germination stage, with seedling shoots. After categorization, physical and physiological quality was assessed. In freshly collected seeds, only category I was observed. At 270 days, approximately 40% of seeds were in category III in laboratory conditions, while the maintenance in a cold chamber delayed germinative metabolism. Viability tests showed that seeds in categories III and IV were more susceptible to damage caused by storage.In conclusion, the percentage of viable A. angustifolia seeds depends on the development stage after collection. Seeds that have reached early developmental category III should be prioritized for propagation, while those remaining in categories I and II should be longer stored with periodic assessment for reduction in physiological quality.

A new approach towards the so-called recalcitrant seeds

“…Among the groups that persist in the area, the panel that was demonstrated up to two decades ago did not change much afterward (Figure 1). The majority of the studies are basically focused on desiccation tolerance Corsato et al, 2012;Chapell et al, 2015;Amoedo and Ferraz, 2017;Gasparin et al, 2017;Subbiah et al, 2017;Chandra and Keshavkant, 2018;Plitta-Michalak et al, 2018), identification of storage behavior (Comin et al, 2014;Joshi et al, 2015;Vicente et al, 2016; 2017; Plitta-Michalak et al, 2018), analysis of deterioration and evaluation of techniques to extend the storage period (Barbedo and Cicero, 2000;Andréo et al, 2006;Bonjovani and Barbedo, 2008;Ballesteros et al, 2014;Lan et al, 2014;Parkhey et al, 2014;Garcia et al, 2015;Ming-Yue et al, 2015;Umarani et al, 2015;Araldi et al, 2016;Hossel et al, 2016;Félix et al, 2017), and rare studying other aspects such as seed maturation (Avila et al, 2009;Lamarca et al, 2013b;Mata et al, 2013;Schultz et al, 2014;Araldi and Coelho, 2015;Shibata and Coelho, 2016;Souza et al, 2018a, b), whose importance will be discussed later, and ecological (Ramlall et al, 2015;Vaz et al, 2016;Porto et al, 2018) or germinative aspects (Moothoo-Padayachie et al, 2016). An analysis, albeit superficial, of studies developed in Brazil and in the world shows small differences.…”

Storage Potential of Local Brazilian Pine Seed Varieties

“…Brazilian pine seeds remain metabolically active during storage, and present changes associated with the germination process (Amarante et al, 2007;Araldi & Coelho, 2015a); a characteristic that constitutes the basis of its recalcitrant behavior (Pammenter & Berjak, 2013). In fact, seed germination under storage was observed inside the plastic package.…”

“…If the conditions are not ideal for completing the process (as in the case of the seeds that remain stored), deterioration will commence (Pammenter & Berjak, 2013;Walters, 2015). Therefore, Brazilian pine seeds that maintain pre-germinative metabolism for longer can be stored for a longer period (Araldi & Coelho, 2015a). …”

Reserve metabolism of stored and germinated Araucaria angustifolia seeds

“…However, seeds from local varieties of A. angustifolia showed great diversity of physical and physiological parameters, which may reflect that a relevant genetic diversity is still present (Shibata, Coelho, Araldi, Adan, & Peroni, 2016;Araldi, Coelho, & Shibata, 2018). Its mature seeds are formed by a bulky megagametophyte, the major storage tissue, and an embryo, which represents only 1.3% of the total weight of the seed (Araldi & Coelho, 2015). Starch and protein have been considered the most important reserve compounds in mature seeds of A. angustifolia (Panza, Láinez, Maroder, Prego, & Maldonado, 2002;Balbuena et al, 2011;Araldi, Coelho, & Maraschin, 2016).…”

“…Germination process events, including an increase in the levels of protein synthesis and meristem cell metabolism, initiate shortly after shedding of A. angustifolia seeds and continue during storage (Farrant, Pammenter & Berjak, 1989). Additionally, there is visual evidence of the onset of germination in seeds stored for 30 days inside transparent plastic containers in the natural environment without the supply of additional water (Araldi & Coelho, 2015). These authors suggested that heterogeneity in the degree of seed maturity is an important aspect in determining the storability of A. angustifolia seeds.…”