Desiccation rate, desiccation response and damage accumulation: can desiccation sensitivity be quantified?

Abstract

This paper presents and assesses a simple model designed to quantify the desiccation sensitivity or degree of recalcitrance of the seeds of Trichilia dregeana, Ekebergia capensis and Quercus robur based on water content, water loss, and intensity and duration of water stress.

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

“…Portanto, os resultados apresentados reforçam a hipótese da existência de níveis de recalcitrância (Berjak & Pammenter 1994, Pammenter & Berjak 1999, Pammenter et al 2003, demonstrando a diversidade de respostas das sementes enquadradas em apenas um ou dois grupos (reclacitrantes e/ou Tabela 3. Germinação de embriões de Inga vera subsp.…”

“…Esse conceito é aceito, ainda, por muitos autores, acrescentando-se a categoria das intermediárias, que também seriam intolerantes às temperaturas de congelamento e, ainda, intolerantes à secagem até 10% de água (Ellis et al 1990, Mai-Hong et al 2006, Usberti et al 2006. Por outro lado, há autores que consideram a existência de níveis de recalcitrância (Berjak & Pammenter 1994, Pammenter & Berjak 1999, Pammenter et al 2003, demonstrando a diversidade de respostas das sementes enquadradas em apenas um ou dois grupos (recalcitrantes e/ou intermediárias). Essas formas de classificação ou agrupamentos são importantes, por exemplo, para que se definam estratégias e técnicas diferenciadas de conservação de germoplasma.…”

Desiccation sensitivity of excised embryonic axes of selected amaryllid species

“…*Correspondence Fax: þ 27 31 260 1195 Email: pammente@ukzn.ac.za nucifera (Chin, 1978), Zizania palustris (Probert and Longley, 1989) and Scadoxus membranaceus , also produce recalcitrant seeds. Dussert et al, 2000;Liang and Sun, 2002;Pammenter et al, 2003), since response to drying is not only species specific Hong and Ellis, 1990), but influenced by the rate (Finch-Savage, 1992;Pammenter et al, 1998Pammenter et al, , 2003Walters et al, 2001) and temperature (Bradford, 1995) of dehydration, as well as provenance (Dussert et al, 2000;reviewed by Dickie and Pritchard, 2002). The ephemeral nature of amaryllid seeds, nonsustainable harvesting of their bulbs for traditional medicinal purposes and habitat loss have led to the endangered or near-threatened status of over half of the 210 species endemic to South Africa (Snijman, 2000).…”

Increasing the rate of drying reduces metabolic imbalance, lipid peroxidation and critical water content in radicles of garden pea (Pisum sativum L.)

“…Drying rates were assessed either as the rate constant (β) of an exponential decline in water content (Liang and Sun, 2000;Sun, 2002), calculated as slopes of log-transformed water contents against time, or as the constant (b) of the modifi ed inverse function relating relative water content (RWC) to time (RWC = b/(b + t), where RWC is the water content relative to the initial water content, and t is drying time 2003), b being calculated as the slope of a plot of 1/RWC against time.…”