title: Interchangeable effects of gibberellic acid and temperature on embryo growth, seed germination and epicotyl emergence in Ribes multiflorum ssp. sandalioticum (Grossulariaceae).
abstract: Morphophysiological dormancy was investigated in seeds of Ribes multiflorum Kit ex Roem et Schult. ssp. sandalioticum Arrigoni, a rare mountain species endemic to Sardinia (Italy). There were no differences in imbibition rates between intact and scarified seeds, suggesting a lack of physical dormancy, while methylene blue solution (0.5%) highlighted a preferential pathway for solution entrance through the raphe. Embryos were small at seed dispersal, with an initial embryo:seed ratio (E:S) of ca. 0.2 (embryo length, ca. 0.5 mm), whereas the critical E:S ratio for germination was three times longer (ca. 0.6). Gibberellic acid (GA(3), 250 mg · l(-1)) and warm stratification (25 °C for 3 months) followed by low temperature (<15 °C) enhanced embryo growth rate (maximum of ca. 0.04 mm · day(-1) at 10 °C) and subsequent seed germination (radicle emergence; ca. 80% at 10 °C). Low germination occurred at warmer temperatures, and cold stratification (5 °C for 3 months) induced secondary dormancy. After radicle emergence, epicotyl emergence was delayed for ca. 2 months for seeds from three different populations. Mean time of epicotyl emergence was affected by GA(3) . Seeds of this species showed non-deep simple (root) - non-deep simple (epicotyl) morphophysiological dormancy, highlighting a high synchronisation with Mediterranean seasonality in all the investigated populations.
authors.affiliation: Centro Conservazione Biodiversità (CCB), Dipartimento di Scienze della Vita e dell'Ambiente, Università degli Studi di Cagliari, Italy. mattana.efisio@gmail.com
authors.forename: E
authors.initials: E
authors.lastname: Mattana
authors.forename: H W
authors.initials: HW
authors.lastname: Pritchard
authors.forename: M
authors.initials: M
authors.lastname: Porceddu
authors.forename: W H
authors.initials: WH
authors.lastname: Stuppy
authors.forename: G
authors.initials: G
authors.lastname: Bacchetta
mesh_terms: D003080:Cold Temperature; D018525:Germination / Q000502:physiology; D005875:Gibberellins / Q000378:metabolism*; D006358:Hot Temperature; D007558:Italy; D057445:Plant Dormancy / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development; D031965:Ribes / Q000254:growth & development* / Q000378:metabolism*; D012621:Seasons; D036226:Seedlings / Q000254:growth & development; D012639:Seeds / Q000254:growth & development
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; C007842:gibberellic acid