Physical, physiological and anatomical changes in Erythrina speciosa Andrews seeds from different seasons related to the dormancy degree

Abstract

Dormancy, a process that allows seeds to survive in adverse environments, needs to be broken for germination to start, for example, by the disruption of the impermeable layer of seeds. Mature seeds of Erythrina speciosa present seed coat impermeability, whose degree depends on the year of production. The objective of this study was to analyze the physical, physiological, anatomical, and ultrastructural seed coat modifications, according to the environmental conditions in which seeds were produced, as well as the seed sensitivity to treatments as for breaking dormancy. E. speciosa seeds were collected for six years in a row and were analyzed as for dormancy degree. Moreover, chemical scarifications by different immersion times were applied on seeds from two production years, as well as mechanical scarification, which was an efficient methodology to overcome dormancy. Different immersion times by acid scarification were necessary to break dormancy in each harvest year. It was possible to conclude that the climatic conditions under which the mother plant is submitted can influence the dormancy degree of E. speciosa seeds, but the expected anatomical changes between dormant and non-dormant seeds were not found in seeds from this species.

A new approach towards the so-called recalcitrant seeds

“…Even dormancy could be seen as one more of the lines, or response surfaces, with possibilities of changes depending on the environment, regardless of the separation into orthodox and recalcitrant. Thus, dormancy must be separated from specific stages of maturation, as proposed by , and may even be induced (Molizane et al, 2018). Therefore, unlike the previous models, which considered dispersed recalcitrant seeds as effectively mature, and that always found several exceptions, all the behaviors are contemplated in this model.…”

Testa structure in Erythrina speciosa (Leguminosae): the role of the mucilaginous stratum in the acquisition of physical dormancy

“…According to Delgado et al (2015), seeds of Erythrina speciosa Andrews (Leguminosae, Papilionoideae) exhibit physical dormancy. However, Molizane et al (2018) demonstrated that the proportion of seeds in physical dormancy in this species could vary according to parental environmental conditions. According to these authors, in years when there is a higher water deficit during seed formation, only 2 % of produced seeds germinated without scarification.…”

“…According to these authors, in years when there is a higher water deficit during seed formation, only 2 % of produced seeds germinated without scarification. In years with greater availability of water during seed formation, germination reached 40 % without dormancy breaking treatments (Molizane et al 2018). In addition, Magalhães (2016) observed a difference in the imbibition of E. speciosa seeds when analyzed immediately after dispersion and after storage.…”

“…In many leguminous seeds, an amorphous layer is observed near the outer periclinal face of the cell walls of the exotestal palisade cells (Werker 1997). Many studies refer to this stratum as a cuticle (Corner 1976;Arechavaleta-Medina & Snyder 1981;Ma et al 2004;Shao et al 2007;Smýkal et al 2014;Molizane et al 2018). However, other studies indicate that it is a mucilaginous stratum (sensu Boesewinkel & Bouman 1984) because both this layer and the walls of the palisade cells are impregnated with pectic substances (Werker 1997).…”

Effect of the seed maturation stage and pre-germination treatments on emergence of Erythrina crista-galli L.

“…On the other hand, environmental conditions under which the plant is subjected during seed production may interfere with the establishment of physical dormancy (Molizane et al 2018;Penfield & MacGregor, 2017). Germination of Erythrina speciosa seeds from the same population followed for six years showed strong interannual variation (Molizane et al 2018). The authors attribute this oscillation in germination over the years to different degrees of dormancy, correlating it to environmental conditions (i.e.…”