Seed dormancy in Acer: Is there a common mechanism for all Acer species and what part is played in it by abscisic acid?

Abstract

S.M. 1987. Seed dormancy in Acer: Is there a coitimon mechanism for all Acer spedes and what part is played in it by abscisic acid? -Physiol. Plant. 71: 365-371.Seeds of Acer pseudoplatanus L. are usually considered to show only testa-imposed dormancy, but a transient embryo dormancy has also been identified at the time of fruit dispersal. Even embryos that did not show full dormancy at this stage possessed iow germinative vigour. Removal of embryo dormancy and the development of increased germination potential did not require the low temperatures necessary for the removal of testa-imposed dormancy in this spedes. Germination rates of embryos from freshly harvested or briefly stored fruits were accelerated by removal of cotyledonary tissue, the most rapid responses occurring in isolated embryonic axes following complete removal of both cotyledons. Longer storage reduced this effect because of the increases in germinative vigour of whole embryos. Abscisic acid (ABA) reinforced embryo dormancy in embryos from freshly harvested or briefly stored fruits and also reduced germination rates in similarly derived isolated embryonic axes. This response to ABA also became progressively less marked as the storage period was extended. Loss of embryo dormancy was correlated with a reduction in endogenous abscisic add levels in both whole embryos and cotyledons, suggesting that endogenous ABA contributes to the regulation of embryo dormancy in these seeds. There are no indications, however, that endogenous ABA is directly implicated in the low temperature processes associated with the removal of testa-imposed dormancy. The relevance of embryo donnancy in the intact seed of A. pseudoplatanus is discussed.

Germinability after desiccation, storage and cryopreservation of seeds from endemic Encholirium Mart. ex Schult. & Schult. f. and Dyckia Schult. & Schult. f. species (Bromeliaceae)

“…The promotive effect of artificial drying on germination was interpreted by Tompsett & Pritchard (1998) as a continuation of the maturation process occurring naturally when seeds become drier. In addition, increasing of seed germination by chilling has been reported in a range of species (Gosling 1989) and a decrease in ABA content after cold stratification in dormant seeds was described in apple (Lee & Looney 1978) and Acer L. species (Pinfield et al 1987). As suggested for other species (Powell 1987), it is possible that ABA reduction is involved in dormancy loss and subsequent germination.…”

Cryopreservation of seeds ofEncholirium spectabileMartius ex Schultes f. by the vitrification method

“…Agreeing with the same author, Rocha (2009) found that with an increase in the time cotton seeds remain in liquid nitrogen, seed germination and vigour also increase. This may be related to the degradation at low temperatures of abscisic acid, a germination inhibitor (LEE;LOONEY, 1978;PINFIELD;STUTCHBURRY;BAZAID, 1987;POWELL, 1987).…”

Seed dormancy in relation to seed storage behaviour in Acer

“…Pinfield & Dungey (1985) divided Acer species that produce dormant seeds into those whose propagules that have an embryo dormancy (embryos do not germinate even when isolated from seed coats) and those in which dormancy can best be described as testa‐imposed (embryos germinate as soon as the seed coats are removed). However, the distinction between these two categories is often not very clear, and seeds of many species may show features associated with both kinds of dormancy (see for example Webb & Dumbroff (1969) for Acer saccharum, Dumbroff & Webb (1970) for Acer ginnala , Wilson, Hibbs & Fischer (1979) for Acer pensylvanicum , Pinfield, Stutchbury & Bazaid (1987) for Acer pseudoplatanus ). Furthermore, Thomas, Webb & Wareing (1973) found that embryos are dormant during seed maturation in Acer pseudoplatanus , a species traditionally classified as having seeds with testa‐imposed dormancy.…”