Physiological and cytological aspects of Inga vera subsp. affinis embryos during storage

Abstract

The remarkably short storability of recalcitrant seeds has prevented their inclusion in programs of ex situ conservation. The causes of their desiccation sensitivity and rapid decline in viability during storage are not fully elucidated yet. In this study the highly recalcitrant, fully viable embryos of the tree species Inga vera subsp. affinis were stored under various conditions and analyzed physiologically and cytologically at intervals, in order to obtain more insights in their loss of viability during storage. Embryos stored fully hydrated at 5 o C fully lost viability in 18 d. Sealed storage of partially dehydrated embryos slightly prolonged their viability, with 95% germination being attained after 14 d of storage. However, after 30 d of storage, viability was completely lost. Storage of hydrated embryos in a solution of polyethylene glycol (PEG) at -1.7 MPa water potential was capable of maintaining high germinability until 30 d of storage. When added to the PEG solution, abscisic acid showed a strong temperature-dependent interaction, with a positive effect on the longevity of embryos stored at 20 o C and a negative effect on embryos stored at 5 o C. In any case, embryo viability could be maintained no longer than 50 d. Embryos from seeds collected from the same trees in the following year showed better storability and still attained 45% germination after 62 d of storage. Analysis of cellular alterations during storage and viability loss of the embryos showed disappearance of starch granules and various damages to the cells, such as cell wall folding and cytoplasm fragmentation. Key-words: abscisic acid, polyethylene glycol, recalcitrant seeds, seed conservationAspectos fisiológicos e citológicos de embriões de Inga vera subsp. affinis durante o armazenamento: A capacidade reduzida de armazenamento apresentada pelas sementes recalcitrantes tem impedido sua inclusão em programas de conservação ex situ. As causas da rápida queda da viabilidade durante o armazenamento ainda não estão totalmente elucidadas. Visando, portanto, a um melhor entendimento desse comportamento, embriões de sementes recalcitrantes de Inga vera subsp. affinis foram armazenados sob várias condições e avaliados periodicamente com relação a aspectos fisiológicos e citológicos. Embriões armazenados sem secagem, a 5 o C, perderam totalmente a viabilidade em 18 dias. Embriões parcialmente desidratados apresentaram 95% de germinação após 14 dias de armazenamento em sacos plásticos selados. Entretanto, após 30 dias de armazenamento, a viabilidade foi totalmente perdida. O armazenamento de embriões sem secagem em solução de polietileno glicol (PEG) a um potencial hídrico de -1,7 MPa foi capaz de manter uma alta capacidade de germinação até 30 dias de armazenamento. Quando adicionado à solução de PEG, o ácido abscísico mostrou uma forte interação com a temperatura de armazenamento, com um efeito positivo na longevidade dos embriões armazenados a 20 o C, porém um efeito negativo nos embriões armazenados a 5 o C. No entanto, em nenhuma condição...

Maturação fisiológica de sementes de ingazeiro (Inga striata) Benth

“…As sementes de ingá são classificadas como recalcitrantes MARCoS FIlho, 2003), sendo altamente intolerantes à dessecação e de baixa longevidade natural KAGEyAMA, 1994;PRITChARD;HAyE;STEADMAN, 1995;BIlIA, 1997;CíCERo, 1998;FARIA et al, 2006). Esse tipo de semente é de grande interesse para estudos que buscam o desenvolvimento de procedimentos visando ampliar a capacidade de armazenamento em sementes recalcitrantes (CoRVEllo et al, 1999;MARCoS FIlho, 2003).…”

“…Inga, como I. uruguensis, I. vera, I. sessilis e I. laurina, o alto porcentual germinativo e rápido desenvolvimento de suas plântulas em áreas abertas (BARBEDo; BIlIA, 1997;NoVEMBRE, 1999;FARIA et al, 2006) as torna adequadas para serem utilizadas para reflorestamento, ornamentação e sombreamento das culturas de café e cacau devido a estrutura da copa.…”

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

“…Indeed, these seeds can be stored only up to seven days without utilization of artificial methods (Bilia et al, 1999). The storage of hydrated embryos in polyethylene glycol (PEG) solution was capable of maintaining high germinability until 30 days of storage at -1.7 MPa and 5 ºC (Faria et al, 2006) and 90 days at -2.4 MPa and 10 °C (Andréo et al, 2006). The seeds of Eugenia uniflora L. (Myrtaceae) also exhibit short storability, but higher than I. vera, and could be stored for six months under controlled conditions .…”

Reduced Sensitivity of <i>Campomanesia adamantium</i> (Cambess.) O. Berg Seeds to Desiccation: Effects of Polyethylene Glycol and Abscisic Acid

“…One possible approach for storing seeds that are intolerant to water content reductions is the osmotic way using polyethylene glycol (PEG) [5] with or without the addition of germination inhibitors, such as abscisic acid (ABA). During this, the germination process is induced by soaking seeds in water or in solutions containing exogenous molecules [6] controlling seed hydration up to a certain level.…”

“…The use of osmotic techniques allows for reduction sensitivity in some recalcitrant seeds to desiccation and/or increases their longevity [5], but generally the major efforts limits the evaluations concerning the primary root protrusion and do not evaluate the completeness normal seedlings. However, to ascertain the effectiveness of these techniques in C. adamantium the hypothesis of this paper was that C. adamantium seeds can be desiccated through the fast or slow drying to less than 15% moisture content with PEG and ABA so that they maintain a high germination rate and vigor.…”