Germination capacity of five polar Caryophyllaceae and Poaceae species under different temperature conditions

摘要

A compilation of the literature relating to the germination of five species of polar vascular plants, Cerastium alpinum, Colobanthus quitensis, Silene involucrata, Deschampsia antarctica and Poa annua, indicates that optimal temperature conditions for seed germination have never been identified for some of them, and the results reported for the remaining species are largely inconclusive. Our results and published findings suggest that significant differences in the germinability of the analysed five species and their species-specific germination responses to temperature and cold stratification could result from variations in their physiological dormancy levels. It is important that seed physiological development at time of collection, seed storing time and conditions are as equal as possible when comparing results from different studies. Our study revealed differences in the maximum germination percentages of those species, which ranged from very low (C. alpinum, 10 %) to very high (S. involucrata, 99 %). Silene involucrata, C. quitensis and D. antarctica have fast-germinating seeds, whereas P. annua is a long germinating species. Within the range of four tested temperatures (12, 20, 20/7 and 30/20 A degrees C), the lowest germination percentage of S. involucrata seeds was observed at fluctuating temperature of 30/20 A degrees C and C. quitensis seeds at 12 A degrees C, the highest germination percentage of C. quitensis seeds was reported at fluctuating temperature of 20/7 A degrees C and P. annua seeds at 12 A degrees C, whereas the germination percentage of D. antarctica was not affected by temperature. A two-month cold stratification period stimulated germination in C. quitensis and D. antarctica, but it did not affect the germination of C. alpinum.