Effects of germination time on seed morph ratio in a seed-dimorphic species and possible ecological significance.
OBJECTIVE
Diaspores of heteromorphic species may germinate at different times due to distinct dormancy-breaking and germination requirements, and this difference can influence life history traits. The primary aim of this study was to determine the effect of germination time of the two seed morphs of Suaeda corniculata subsp. mongolica on life history traits of the offspring.


METHODS
Germinated brown and black seeds were sown on the 20th of each month from April to September in a simulated but near-natural habitat of the species. Phenological and vegetative traits of the maternal plants, and number, size and germination percentage of the offspring were determined.


RESULTS
Germinated seeds sown late in the year produced smaller plants that had a higher proportion of non-dormant brown than dormant black seeds, and these brown seeds were larger than those produced by germinated seeds sown early in the year. The length of the seedling stage for brown seeds was shorter than that for black seeds, and the root/shoot ratio and reproductive allocation of plants from brown seeds were more variable than they were for plants from black seeds. Late-germinating brown seeds produced larger plants than late-germinating black seeds.


CONCLUSIONS
Altering the proportion of the two seed types in response to germination timing can help alleviate the adverse effects of delayed germination. The flexible strategy of a species, such as S. corniculata, that produces different proportions of dimorphic seeds in response to variation in germination timing may favour the maintenance and regeneration of the population in its unpredictable environment.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Fan
F
Yang
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Jerry M
JM
Baskin
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Carol C
CC
Baskin
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Xuejun
X
Yang
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA.
Dechang
D
Cao
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, University of Chinese Academy of Sciences, Beijing 100039, China and Department of Biology and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA zhenying@ibcas.ac.cn.
Zhenying
Z
Huang
D019663:Chenopodiaceae / Q000235:genetics / Q000254:growth & development*; D002681:China; D018525:Germination; D057445:Plant Dormancy; D036226:Seedlings / Q000254:growth & development; D012639:Seeds / Q000254:growth & development*
Germination timing; Suaeda corniculata; life history traits; maternal environmental effect; phenology; phenotypic plasticity; seed germination; seed heteromorphism