Seed germination in <em>Ormosia macrocalyx</em>, an endangered tropical forest tree

Abstract

Background: Ormosia macrocalyx is a tropical forest tree classified as endangered. Its seeds experience problems of dispersion and apparent physical dormancy due to their hard seed coating. Hypotheses: 1) The stages of dehiscence of the fruits of Ormosia macrocalyx influence the germinative behavior of its seeds. 2) Pregerminative treatments will improve the germination process of the seeds stored under refrigeration. Study species: Ormosia macrocalyx Study site and period: Villahermosa, Tabasco, Mexico from October 2012 to October 2014 Methods: Two completely randomized experiments were conducted in order to analyze the germination process by 1) evaluating germination in seeds from fruit at three stages of dehiscence (closed, semi-open, and open fruit) and 2) applying four treatments, including three pregerminative treatments (water soaking for 24 h, mechanical scarification and scarification+1% gibberellic acid) plus an untreated control, to seeds stored under refrigeration for 17 months. Results: Differences were found in germination rate (GR), corrected germination rate (CGR) and time to attain 50 % germination (T 50 ) among treatments in the first experiment, with the seeds from open fruits presenting the lowest response (3.31 % day -1 for GR and CGR, and 15.8 days for T 50 ), although all treatments showed similar times for the initiation of germination (GI) and final germination percentage (GP). In the second experiment, the effect of scarification was greater than both the control and soaking treatments. Scarification treatment values were 68.0 % (GP), 12.0 days (GI), 4.53 % day -1 (GR), 6.65 (CGR) and 14.5 days (T 50 ). Addition of gibberellic acid did not produce any further advantage over scarification alone. Conclusions:Seeds from open fruits have lower germination rates, although the final GP is not affected. Stored seeds present physical dormancy but lose viability with storage and, when collected after remaining attached to the tree for undefined periods, scarification can greatly improve their germination rate. Key words: fruit maturation, dormancy, pregerminative treatments, storage Germinación de semillas de Ormosia macrocalyx, un árbol forestal amenazado ResumenAntecedentes: Ormosia macrocalyx es un árbol tropical amenazado. Sus semillas tienen problemas de dispersión y aparente latencia física por cubierta seminal dura. Hipótesis: 1) Las etapas de dehiscencia de los frutos de Ormosia macrocalyx repercutirán en el comportamiento germinativo de sus semillas. 2) Los tratamientos pregerminativos mejorarán el proceso germinativo de las semillas almacenadas en refrigeración Especie de estudio: Ormosia macrocalyx Ducke. Sitio de estudio y fechas: Villahermosa, Tabasco, México, octubre 2012-octubre 2014 Métodos: Se establecieron dos experimentos completamente aleatorios para analizar el proceso de la germinación: 1) Evaluación de la germinación en semillas de frutos en tres estados de madurez (cerrados, semi-abiertos y abiertos), y 2) Aplicación de cuatro tratamientos, tres pregerminativos (r...

Seed anatomy and water uptake and their relation to seed dormancy of Ormosia paraensis Ducke

“…However, water uptake by O. paraensis seeds was observed after mechanical scarification due to integument rupture and a consequent exposure of parenchyma cells of the embryo cotyledon (Figures 1 and 2C-D). Vargas-Simón et al (2017) observed the highest percentages of germination in seeds of O. macrocalyx Ducke by means of mechanical scarification or its combination with gibberellic acid, which presented values of 68.0 and 61.3%, respectively.…”

“…Because of their hardness and resistance, seeds of several Ormosia species are used for making handicrafts. However, this hardness hinders seed analysis and seedling production (Lopes et al, 2006;Gonçalves et al, 2011;Baigts, 2009;Teixeira et al, 2009;Basqueira et al, 2011;Curiel and Morais, 2011;Gurski et al, 2012;Silva and Moraes, 2012;Silva et al, 2014;Silva et al, 2015;Vargas-Simón et al, 2017).…”

“…Harms, Silva et al (2014) indicated seed soaking in sulfuric acid (100%) for 15 minutes to obtain 91% germination, while Lopes et al (2006) recommended seed soaking in sulfuric acid for 10 minutes or mechanical abrasion to achieve 96% germination in O. nitida Vogel seeds. Moreover, for O. macrocalyx Ducke, the indication is the isolated use of mechanical scarification or mechanical scarification followed by gibberellic acid (GA 3 ) application to overcome seed dormancy (Vargas-Simón et al, 2017).…”

GROWTH RHYTHMS OF THREE Ormosia SPECIES SEEDLINGS OF DIFFERENT PROVENANCES

“…At present, most researches on Ormosia species are mainly concentrated on tissue culture (He et al, 2015;Fan et al, 2011), seed reproductive ecology (Peng et al, 2009;Chen, 2016), seed germination (Vargas-Simón et al, 2017;Silva et al, 2014;Foster, 2008), seedling cultivation (Shen et al, 2009;Ye, 2014;Yang, 2011;Feng et al, 2007;Zhu et al, 2015), fertilization measures (Duan et al, 2017;Zheng, 2008) and forest afforestation techniques (Wu et al, 2009;Pan, 2004), while few studies have been performed on the growth rhythm of O. hosiei, O. xylocarpa and O. henryi from different provenances. Hence, this study is aimed to evaluate the growth rhythms and differences of the three species from different provenances for selecting the superior provenances of O. hosiei, O. xylocarpa and O. henryi for priority use and determining appropriate management technique.…”