Mobilization of reserves and germination of seeds of Erythrina velutina Willd. (Leguminosae - Papilionoideae) under different osmotic potentials

Abstract

-Some environmental factors, including water availability, may influence seed germination. This study investigated the germination of E. velutina seeds submitted to different osmotic potentials and mobilization of reserves during water-stress. Scarified seeds were arranged in paper rolls and soaked in solutions of Polyethylene Glycol (PEG) prepared in osmotic potentials 0.0, -0.2, -0.4, -0.6, and -0.8 MPa and kept into a seed germinator, at 25 °C, and 12/12 h photoperiod (L/D), during 10 days. The percentage, mean time, mean speed, germination speed index; as well as the germination uniformity coefficient were assessed. During germination process the total soluble sugars, reducing sugars, soluble protein, and total amino acids were quantified in the cotyledon, hypocotyl and radicle of soaked seeds and cotyledons of quiescent seeds (control). There was influence of osmotic potential on E. velutina seed germination. The germination percentage remained at high levels until -0.6 MPa and above this osmotic potential there has been no germination. The mobilization of stored reserves of carbon and nitrogen in E. velutina seeds was also influenced by water-stress. There was sensitiveness between -0.2 and -0.6 MPa; however, the degradation and the mobilization of reserves was slower when the osmotic potential decreased.Index terms: PEG 6000, water-stress, carbon of storage, soluble proteins, "mulungu", "caatinga".Mobilização de reservas e germinação de sementes de Erythrina velutina Willd. (Leguminosae -Papilionoideae) sob diferentes potenciais osmóticos RESUMO -Alguns fatores ambientais podem influenciar a germinação, dentre eles a disponibilidade hídrica para as sementes. Este estudo investigou a germinação e a mobilização de reservas de sementes de E. velutina, submetidas a diferentes potenciais osmóticos. As sementes escarificadas foram embebidas em soluções de PEG preparadas em potenciais osmóticos de 0,0, -0,2, -0,4, -0,6 e -0,8 MPa, dispostas em rolos de papel e mantidas em germinador, a 25 °C e fotoperíodo de 12/12 h (L/E), durante 10 dias. Foi avaliado: porcentagem, tempo médio, velocidade média e índice de velocidade de germinação; e coeficiente de uniformidade de germinação. Durante a germinação foram quantificados: açúcares solúveis totais, açúcares redutores, proteínas solúveis e aminoácidos totais nos cotilédones, no hipocótilo e na radícula das sementes embebidas e nos cotilédones de sementes quiescentes (controle). Houve influência do potencial osmótico na germinação de sementes de mulungu. A porcentagem de germinação permaneceu em níveis elevados até -0,6 MPa; acima deste potencial não houve germinação. A mobilização de reservas de carbono e nitrogênio em sementes de E. velutina também foi influenciada pelo estresse hídrico. Houve sensibilidade entre -0,2 e -0,6 MPa, no entanto, a degradação e a mobilização de reservas foi mais lenta quando o potencial osmótico foi diminuído.Termos para indexação: PEG 6000, estresse hídrico, carbono de reserva, proteínas solúveis, mulungu, caatinga.

Alternating temperature and accelerated aging in mobilization of reserves during germination of Carica papaya L. seeds

“…Nevertheless, mobilization undergoes the effect of osmotic components (Reis et al, 2012), of salinity (Silva et al, 2008;Dantas et al, 2014), of light and growth regulators (Ren et al, 2007;Zanotti et al, 2014), of accelerated aging (Zhu and Chen, 2007;Menezes et al, 2014), and of storage (Abbade and Takaki, 2014), factors which may accelerate or slow the process, as well as hurt the development of normal seedlings.…”

“…Conditions unfavorable to water supply (Reis et al, 2012) and temperature, as well as deterioration processes (MarcosFilho, 2005), may alter or interrupt mobilization of reserves, hurting germination. Thus, the aim of this study was to identify the phases of water absorption during germination of papaya (Carica papaya L.) seeds and evaluate the effect of alternating temperature and accelerated aging on mobilization of reserves during germination.…”

Caracterization of seed germination of Zephyranthes sylvatica (Mart.) Baker (Amarilidacea)

“…It is triggered by persistent lack of significant rainfall, where the spatial and temporal variability of precipitation makes the occurrence of this phenomenon more frequent (Reis et al, 2012). As a result, many Caatinga native or well adapted species are tolerant to osmotic stress, such as the trees Apeiba tibourbou Aubl (Guedes et al, 2013), Erythrina velutina (Reis et al, 2012), Mimosa caesalpiniifolia (Moura et al, 2011) and Myracrodruon urundeuva (Virgens et al, 2012); the shrubs Cajanus cajan (Marin et al, 2004), ** value significant at 1%.…”

Estresse hídrico e térmico na germinação de sementes de Leucaena leucocephala (Lam.) de Wit

“…Em comparação com espécies arbóreas nativas do semiárido, a exemplo de C. pyramidalis (Antunes et al, 2011), E. velutina (Reis et al, 2012), A. cearensis (Almeida et al, 2014;Oliveira et al, 2014), M. urundeuva, S. brasiliensis e S. obtusifolium (Oliveira et al, 2014), a L. leucocephala pode ser considerada pouco tolerante ao estresse hídrico e térmico durante as fases de germinação das sementes e de crescimento inicial das plântulas.…”

“…(Miranda et al, 2014) e as nativas Erythrina velutina Willd. (Reis et al, 2012), Poincianella pyramidalis Tul. L. P. Queiroz (Antunes et al, 2011), Amburana cearensis (Allemão) A.C. Smith (Almeida et al, 2014;Oliveira et al, 2014), Myracrodruon urundeuva Fr.…”