Dormancy and germination of the trimorphic achenes of a cold desert annual: spreading the risk over time. Issue 6 (23rd October 2020)

• Record Type: Journal Article
• Authors: Lu, Juanjuan; Dong, Wenjing; Tan, Dunyan; Baskin, Carol C; Baskin, Jerry M
• Editors: Auge, Gabriela
• Is Part Of: AoB plants. Volume 12:Issue 6(2020)
• Publication Date: 2020-10-23
• Subjects: Asteraceae -- diaspore heteromorphism -- germination phenology -- high risk/low risk dispersal–dormancy strategy -- physiological dormancy -- temporal dispersal -- unpredictable-precipitation environment; Plants -- Periodicals; Botany -- Periodicals; 580.5
• DOI: 10.1093/aobpla/plaa056
• Languages: English
• ISSNs: 2041-2851

Abstract

Abstract: Many studies have been done on the relationship between variation in morphology, dispersal ability and degree of dormancy of heterocarpic species with dimorphic diaspores. However, there are far fewer such studies on species that produce trimorphic diaspores. Our aim was to compare dormancy and germination of achenes from peripheral, intermediate and central positions in the capitulum of the diaspore-trimorphic cold desert annual Asteraceae species Heteracia szovitsii, an important component of plant communities in the cold deserts of NW China. Dormancy breaking/germination responses of the three achene morphs and of seeds isolated from the pericarp were tested in the laboratory using standard procedures, and seedling emergence phenology of the achene morphs was monitored under natural cold desert temperature conditions in an experimental garden with and without supplemental watering. Depth of dormancy of the three achene morphs was peripheral > intermediate > central. Seedlings from the three morphs emerged in spring and in autumn. Cumulative seedling emergence percentage from achenes during 47 months of burial was central > intermediate > peripheral. Central achene morphs emerged over a period of ~12 months after sowing, while intermediate and peripheral achene morphs did so for ~40 and 47 months, respectively. Thus, H. szovitsii exhibits a temporal dispersal strategy. No viable central or intermediate achene morphs were present after 16 and 40 months, respectively, but ~60 % of the non-emerged peripheral achenes morphs were viable after 47 months. Based on our results on diaspore dormancy and those of a previous study of diaspore spatial dispersal of H. szovitsii, we conclude that this species has a high–intermediate–low risk diaspore dispersal/dormancy strategy that likely increases the chances for population persistence over time and space. Abstract : Relatively little is known about the relationship between variation in morphology, degree of dormancy and dispersal ability of heterocarpic species with trimorphic diaspores. Lu et al. investigated diaspore dormancy of Heteracia szovitsii and combined the results with data from a previous study of diaspore dispersal of this species. They concluded that H. szovitsii has a high–intermediate–low risk diaspore dispersal/dormancy strategy, which likely increases the chances for population persistence over time and space in its cold desert habitat in Central Asia.