Unraveling the Effects of Cold Stratification and Temperature on the Seed Germination of Invasive Spartina alterniflora Across Latitude

Abstract

Seed germination is critical to the life history of plants, playing an important role in the successful recruitment, colonization, and even invasion of new individuals within and outside population distribution ranges. Cold stratification and temperature are the key factors affecting seed germination traits. Studying how these two factors drive geographical variation in seed germination is essential to analyze and predict the geographical distribution range of alien plants in novel habitats. Spartina alterniflora, native to the United States, was introduced into China in 1979 and has spread over 20° of latitude along the eastern coast of China. Germination plays a crucial role in S. alterniflora’s large-scale invasion and diffusion across latitude. To evaluate the effects of cold stratification and temperature on seed germination of S. alterniflora across latitude, we collected seeds at seven locations across latitude in China. We exposed these provenances to cold stratification at 4°C (0, 1, 3, and 5 months) and germination temperature (5°C, 15°C, 25°C, and 35°C) treatments in growth chambers. Seed germination was observed for 98 days, and we calculated germination rate, germination index, and germination time. Results indicated that longer cold stratification significantly promoted germination rate and germination index, but decreased germination time. Similarly, higher germination temperature significantly promoted germination rate and germination index, but decreased germination time. Moreover, there were significant interactive effects on germination traits between cold stratification and temperature. Seed germination traits showed linear relationships with latitude, indicating that S. alterniflora seeds from different provenances germinated at different times and adopted different germination strategies. The stratification and temperature are the most important factors regulating the dormancy and germination seeds, so they can be important drivers of this variation along latitude. Under scenarios of warmer regional temperature, seeds at higher latitudes could germinate earlier and have higher germination rate, which would favor a potential northern expansion of this invasive plant.

Effects of warming on seed germination of woody species in temperate secondary forests

“…Warming increased the GI for five species, which indicates that warming promotes the germination capacity of seeds for these species. Our result is consistent with other studies showing that warming could increase GI for specific species (Wei et al 2020;Cheng et al 2022). The highest GI values were calculated for P. asperata without cold stratification.…”

“…2020; Cheng et al . 2022). The highest GI values were calculated for P. asperata without cold stratification.…”

Regional Variation in Phragmites australis Reproductive Traits and Seedling Performance in North America

“…For example, invasive Ambrosia artemisiifolia in China exhibited lower germination in seeds from Northeastern latitude populations versus Southeast populations (Zhou et al 2021). Invasive Spartina alterniflora populations in China displayed the opposite pattern, with populations in Northeastern China exhibiting a higher percent germination than populations from the Southeast (Cheng et al 2022). Thus, our results show that Phragmites populations from the Northeast invested more into inflorescences, but this investment did not translate into increased seed mass or germination.…”

The Impact of Water Potential and Temperature on Native Species’ Capability for Seed Germination in the Loess Plateau Region, China

“…One major environmental element that can control enzyme activity and either stimulate or prevent the generation of hormones that influence seed germination is temperature [ 15 , 19 , 20 , 21 ]. The germination responses of seed lots to temperature can be characterized through three cardinal temperatures [ 22 , 23 ]: a base temperature ( T b ), below which the seeds do not germinate; an optimal temperature ( T o ), at which the process proceeds at its fastest pace; and a ceiling temperature ( T c ), above which the process is stopped [ 24 , 25 , 26 ].…”

“…The most vital phase of plant development and the beginning point of a new population is thought to be seed germination [ 14 , 19 , 46 ]. In addition, it is one of the more delicate phases of life and can easily result in seed inactivation or failure of establishment [ 47 ].…”