Lu Juanjuan, Dong Wenjing, Tan Dunyan, Baskin Carol C, Baskin Jerry M
College of Grassland and Environment Sciences, Xinjiang Agricultural University, Urümqi, China.
Department of Biology, University of Kentucky, Lexington, KY, USA.
AoB Plants. 2020 Oct 23;12(6):plaa056. doi: 10.1093/aobpla/plaa056. eCollection 2020 Dec.
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 , 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, 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 , 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.
针对具有二形瘦果的异型果物种，已有许多关于其形态变异、扩散能力和休眠程度之间关系的研究。然而，对于产生三形瘦果的物种，此类研究要少得多。我们的目的是比较西北寒漠一年生菊科三形瘦果物种头状花序中外围、中间和中心位置瘦果的休眠和萌发情况，该物种是中国西北寒漠植物群落的重要组成部分。在实验室中使用标准程序测试了三种瘦果形态以及从果皮中分离出的种子的休眠破除/萌发反应，并在有和没有补充浇水的实验园中，在自然寒漠温度条件下监测了瘦果形态的幼苗出土物候。三种瘦果形态的休眠深度为外围＞中间＞中心。三种形态的幼苗在春季和秋季出土。在埋藏47个月期间，瘦果的累积幼苗出土率为中心＞中间＞外围。中心瘦果形态在播种后约12个月内出土，而中间和外围瘦果形态分别在约40和47个月内出土。因此，呈现出一种时间扩散策略。分别在16个月和40个月后，不再存在有活力的中心或中间瘦果形态，但47个月后，约60%未出土的外围瘦果形态仍有活力。基于我们关于瘦果休眠的结果以及先前关于瘦果空间扩散的研究结果，我们得出结论，该物种具有高-中-低风险的瘦果扩散/休眠策略，这可能会增加种群在时间和空间上持续存在的机会。
