Sementes recalcitrantes: intolerantes a baixas temperaturas? Embriões recalcitrantes de Inga vera Willd. subsp. affinis (DC.) T. D. Penn. toleram temperatura sub-zero

Abstract

-(Recalcitrant seeds: intolerant to low temperatures? Recalcitrant embryos of Inga vera Willd. subsp. affinis (DC.) T. D. Penn., a tropical species, are tolerant to subzero temperature). Recalcitrant seeds are intolerant to both desiccation and low temperatures, the most important mechanisms of seed conservation, consequently their storage is difficult. Inga vera subsp. affinis produces the so-called recalcitrant seeds, since they do not survive to water content lower than 35%. In this work it is demonstrated that these seeds are tolerant to temperatures as low as -2 °C. Embryos of I. vera of different stages of maturity were stored at temperatures varying from 8 to -18 °C for until 45 days. Non-dried embryos and both dried to -4 MPa and -6 MPa were stored. Results showed that, despite all embryos died at -18 °C, some cold tolerance was obtained by mature embryos when stored at -2 °C, as long as they are dried to -4 MPa.

Reserve carbohydrates and lipids from the seeds of four tropical tree species with different sensitivity to desiccation

“…The high germinability found in the seeds of E. uniflora and I. vera seeds was consistent with the current literature and with the fact that they were commonly indicated for reforestation (Bilia and Barbedo, 1997). Concerning the carbohydrate quantification, it was possible to separate the studied species into two groups, one including the desiccation tolerant seeds, E. speciosa and C. echinata (Nkang, 2002;Barbedo et al, 2002), both with more than 14% DM as soluble carbohydrates, and the other group represented by E. uniflora and I. vera seeds, with recalcitrant behavior (Delgado and Barbedo, 2007;Bonjovani and Barbedo, 2008) and lower amounts of soluble carbohydrates. A variety of orthodox seeds, including mature legumes, can contain high levels of soluble carbohydrate.…”

SENSIBILIDADE À DESSECAÇÃO DE EMBRIÕES DE Inga vera Willd. FORMADOS SOB DIFERENTES CONDIÇÕES AMBIENTAIS1

“…Para tanto, foram dispostos em prateleiras forradas com tela de polietileno, em camadas simples sem sobreposição. A secagem foi realizada de forma intermitente, com 10 h a 30 ± 1 °C, seguidas de 14 h de repouso a 22 ± 2 °C (BILIA et al, 1999;BARBEDO, 2008). Periodicamente, com base no valor da massa de matéria seca da amostra (g), quatro amostras de 50 embriões foram retiradas e os embriões, avaliados quanto ao teor de água, ao conteúdo de massa de matéria seca e à germinação, conforme descrito anteriormente.…”

“…, valores referenciais para análise da sensibilidade à dessecação (BILIA et al, 1999;BARBEDO, 2008). Esses teores de água constituíram-se nos diferentes níveis de secagem, respectivamente, no primeiro nível de secagem (S I ), o segundo nível de secagem (S II ), o terceiro nível de secagem (S III ) e o quarto nível de secagem (S IV ), além das sementes não submetidas à secagem (S 0 ).…”

“…Para sementes de Inga vera, diversos estudos fisiológicos foram realizados, principalmente quanto ao armazenamento, à exigência térmica para germinação e à tolerância à dessecação (BILIA et al, 1998(BILIA et al, , 1999BARBEDO;CICERO, 2000;FARIA et al, 2004;ANDRÉO et al, 2006;BARBEDO, 2008;LAMARCA et al, 2013a). Todavia, verifica-se que há poucas informações na literatura científica sobre respostas fisiológicas dessas sementes, como a sensibilidade à dessecação em relação às condições do ambiente onde as sementes são formadas.…”

Maturation of seeds of Poincianella pluviosa (Caesalpinoideae)

“…The water potential was measured with a Decagon WP4 potentiometer (Pullman, USA) based on the dew point temperature of the air after equilibrium with the sample, according to Bonjovani and Barbedo (2008). The assessment of the water potential was performed by sorption isotherms in solutions of polyethylene glycol (PEG 6000) at different osmotic potentials, based on Michel and Kaufmann (1973).…”