Timing of seed germination is critical for seedling establishment and growth of the plant to maturity. Theoretically, then, germination of alpine species should be restricted to a period that ensures seedlings will reach a critical size during the short growing season for overwinter survival. We hypothesized that seeds of two alpine monocarpic perennials of Meconopsis germinate only at the beginning of the growing season in early spring and that dormancy synchronizes the timing of germination to this period. We tested the effects of light, temperature, cold stratification and GA3 on germination of Meconopsis integrifolia and M. racemosa in the laboratory and germination responses to temperature during two 2-year periods of seed buried at 4450 m a.s.l. on the Tibetan Plateau. Most fresh seeds of both species were dormant, and the embryo underdeveloped, indicating morphophysiological dormancy (MPD). GA3 promoted embryo growth and germination of seeds. Buried seeds exhibited an annual dormancy cycle. The physiological component of MPD was released gradually in the field during autumn and winter, resulting in embryo growth (release of morphological component of MPD) and germination just after snowmelt in spring. Embryos in seeds that did not germinate the first year remained underdeveloped until the second spring. Delay of seed burial from October until January (simulating a delay in time of seed dispersal) delayed germination for 1 year but did not change the germination season. Thus, our hypothesis that MPD restricts germination to the beginning of the growing season is supported.
|Journal||Environmental and Experimental Botany|
|State||Published - Jul 2021|
Bibliographical noteFunding Information:
We thank Professors Jian Luo and Zhen Xing, Tibet Agricultural and Animal Husbandry College for advice on the experiments; students Xiaoyan Yao, Xi Zhang, Kun Tan and Yifeng Wang for help with field and laboratory work; and the Linzhi National Forest Ecosystem Observation & Research Station for providing meteorological data for the study site. This work was funded by the National Natural Science Foundation of P. R. China ( 31861143024 , 31870711 and 31860123 ) and the Second Tibetan Plateau Scientific Expedition and Research Program of P. R. China ( 2019QZKK0301 ).
© 2021 Elsevier B.V.
- Buried seeds
- Dispersal time
- Dormancy cycling
- Secondary dormancy
- Underdeveloped embryo
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Agronomy and Crop Science
- Plant Science