Ecological adaptation strategies of seed germination in Primula alpicola， an endemic alpine species in the southeastern Xizang Plateau

doi:10.11686/cyxb2025373

Abstract

Abstract:

This study investigated the seed dormancy and germination ecology of Primula alpicola， an endemic alpine species from southeastern Xizang， to understand its adaptive strategies in alpine environments. The scientific problem addressed was the germination constraints faced by seeds in cold climates with short growing seasons. We aimed to determine the type of seed dormancy and evaluate how environmental factors such as temperature， light， gibberellin （GA₃）， dry after-ripening， and cold stratification affect dormancy release and germination. Experiments tested the effects of exogenous GA₃， dry after-ripening， and cold stratification on breaking dormancy， along with germination responses under various temperature regimes （constant： 1， 5， 10， 15， 20， 25， and 30 ℃； alternating： 5 ℃/1 ℃， 15 ℃/5 ℃， 25 ℃/15 ℃） and light conditions （12 hours light/12 hours dark vs. continuous darkness）. Results showed that fresh seeds exhibited non-deep physiological dormancy （type 2）， requiring temperatures above 20 ℃ for germination， which was strongly light-dependent， especially at low temperatures. GA₃ significantly promoted germination， both dry after-ripening and cold stratification alleviated dormancy， with cold stratification being more effective. As dormancy was released， the germination temperature range widened （5-30 ℃）， the base germination temperature （T_b） decreased from -2.092 ℃ （after 3 months cold stratification） to -4.035 ℃ （after 6 months）， while the optimal （T_o） and ceiling （T_c） temperatures remained unchanged， and light dependence diminished. These findings indicate that P. alpicola seeds initially rely on high temperatures for germination， with unfavorable conditions inducing conditional dormancy. Overwintering dormancy loss enables germination at lower temperatures， facilitating rapid seedling establishment after snowmelt. This strategy prolongs the growth period and enhances survival， representing a key adaptation to short alpine growing seasons.

Key words: Primula alpicola, dormancy, germination, cold stratification, dry after-ripening

Na CHEN, Ying-bo QIN, De-li PENG. Ecological adaptation strategies of seed germination in Primula alpicola， an endemic alpine species in the southeastern Xizang Plateau[J]. Acta Prataculturae Sinica, 2026, 35(7): 165-174.

Figures/Tables 7

Fig.1 Effect of temperatures on cumulative germination percentage for fresh seeds of P. alpicola under light conditions

Fig.2 Effect of gibberellin （GA3） and light condition on final germination percentage of fresh seeds

Fig.3 Effects of dry after-ripening （DAR） and cold stratification （CS） on final germination percentage under constant/alternating temperatures and light/dark conditions

Fig.4 Effects of dry after-ripening （DAR） and cold stratification （CS） on mean germination time （MGT） under constant/alternating temperatures （light conditions）

Table 1 Generalized linear model analysis of the effects of light condition， dormancy-breaking treatments， and their interactions on the final germination percentage of P. alpicola under constant and alternating temperature regimes

变异来源 Source of variation	恒温Constant temperature		变温Alternating temperature
变异来源 Source of variation	df	P	df	P
光照条件Light condition	1	<0.000	1	<0.000
低温层积Cold stratification	2	<0.000	2	<0.000
干燥后熟Dry after-ripening	2	<0.000	2	<0.000
光照条件×干燥后熟Light condition×dry after-ripening	2	0.001	2	<0.000
光照条件×低温层积Light condition×cold stratification	2	<0.000	2	0.001

Table 2 Generalized linear model analysis of the effects of dry after-ripening and cold stratification on the mean germination time of P. alpicola under constant and alternating temperature regimes （in light）

变异来源

Source of variation

恒温Constant temperature

变温Alternating temperature

低温层积Cold stratification

<0.000

干燥后熟Dry after-ripening

0.118

<0.000

Fig.5 Linear relationship between temperature and germination rate

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