Seed dormancy regulates germination response to smoke and temperature in a rhizomatous evergreen perennial. Issue 4 (4th July 2018)

• Record Type: Journal Article
• Authors: Ma, Hongyuan; Erickson, Todd E; Merritt, David J
• Is Part Of: AoB plants. Volume 10:Issue 4(2018)
• Publication Date: 2018-07-04
• Subjects: Cold stratification -- dormancy cycling -- embryo growth -- germination stimulant -- secondary dormancy -- temperature; Plants -- Periodicals; Botany -- Periodicals; 580.5
• DOI: 10.1093/aobpla/ply042
• Languages: English
• ISSNs: 2041-2851

Abstract

Abstract: Seed dormancy status regulates the response of seeds to environmental cues that can trigger germination. Anigozanthos flavidus (Haemodoraceae) produces seeds with morphophysiological dormancy (MPD) that are known to germinate in response to smoke, but embryo growth dynamics and germination traits in response to temperatures and after-ripening have not been well characterized. Seeds of A. flavidus, after-ripened for 28 months at 15 °C/15 % relative humidity, were incubated on water agar, water agar containing 1 μM karrikinolide (KAR1 ) or 50 μM glyceronitrile at 5, 10, 15, 20, 25, 20/10 and 25/15 °C for 28 days. After incubation at 5, 10 and 25 °C for 28 days, seeds were transferred to 15 °C for another 28 days. Embryo growth dynamics were tested at 5, 10, 15 and 25 °C. Results demonstrated that fresh seeds of A. flavidus had MPD and the physiological dormancy (PD) component could be broken by either glyceronitrile or dry after-ripening. After-ripened seeds germinated to ≥80 % at 15–20 °C while no additional benefit of germination was observed in the presence of the KAR1 or glyceronitrile. Embryo length significantly increased at 10 °C, and only slightly increased at 5 °C, while growth did not occur at 25 °C. When un-germinated seeds were moved from 5–10 °C to 15 °C for a further 28 days, germination increased from 0 to >80 % in significantly less time indicating that cold stratification may play a key role in the germination process during winter and early spring in A. flavidus . The lower germination (<50 %) of seeds moved from 25 to 15 °C was produced by the induction of secondary dormancy. Induction of secondary dormancy in seeds exposed to warm stratification, a first report for Anigozanthos species, suggests that cycling of PD may be an important mechanism of controlling germination timing in the field. Abstract : Fresh seeds of A. flavidus have differentiated but underdeveloped embryos and possess non-deep morphophysiological dormancy (MPD). The MPD could be broken by smoke-derived chemical of glyceronitrile. However, after-ripened seeds (dry stored at 15 °C for 28 months) could germinate readily at temperatures 15–20 °C while glyceronitrile did not improve germination percent or speed following loss of physiological dormancy (PD). Embryo growth could occur at 5 and 10 °C, faster with increasing temperature, but could not germinate until the temperature was 15 °C. Warm temperature above 25 °C induced secondary dormancy in seeds and no embryo elongation.