Seed germination characteristics of invasive Spartina alterniflora Loisel in Japan: implications for its effective management

Yu Maebara,Tomohiro Kurazono,Moe Nakagawa,Koya Hashimoto,Daisuke Hayasaka

doi:10.1038/s41598-020-58879-7

Abstract

Spartina alterniflora, intentionally or unintentionally introduced worldwide, has adversely impacted local Japanese ecosystems. Thus, prediction of future distributions of S. alterniflora and its management are required. Local population expansion after establishment depends heavily on asexual (clonal) reproduction, whereas sexual (seed) reproduction is one of the critical factors for estimating invasion success and the likelihood of colonization to new habitats. However, knowledge about the germination characteristics of S. alterniflora is lacking. Here, we report the environmental conditions suitable for germination of S. alterniflora, under variable conditions of cold stratification periods (0, 4, 8 weeks), temperature (constant, alternating temperature), light (light/dark, dark), and oxygen (aerobic, anaerobic). Cumulative germination rate of S. alterniflora increased with an increasing period of cold stratification. Its seeds clearly preferred aerobic conditions to germinate. Also, the germination rate was higher under alternating temperature than under constant temperature regardless of light and oxygen conditions in any cold stratification period. However, long-term cold stratification, alternating temperature, and aerobic conditions were more important for germination of S. alterniflora than light. Removal of soil seed banks within 8 weeks of cold stratification after seed dispersals with matured seeds may be effective approaches for disrupting the germination of S. alterniflora.

Highlights

Spartina alterniflora Loisel, native to North America and the Gulf Coast of the Mexico, is a perennial halophyte
Some researchers reported that local population dynamics of higher plants after establishment depend heavily on asexual reproduction regardless of native/non-native or invasive species[19,20], sexual reproduction could be important for colonization success to new habitats via pollen and/or seeds[17,21]
Differences in the germination rate between light/dark and aerobic versus dark and anaerobic conditions became smaller with increasing length of the cold stratification (Figs. 1, 2a)

Summary

Introduction

Spartina alterniflora Loisel (smooth cordgrass), native to North America and the Gulf Coast of the Mexico, is a perennial halophyte. The germination rate of many hygrophytes and halophytes regardless of invasive and native species depends considerably on a combination of the environmental conditions mentioned above[32]. For these reasons, knowledge on the specific germination characteristics of a given species[22,33] including S. alterniflora is essential for understanding germination success. We investigated the suitable environmental conditions on seed germination of the invasive S. alterniflora in Japan, in particular the effects of cold stratification, temperature, light, and oxygen conditions which are important triggers for germination success. Based on our results, we discuss possible effective management strategies for invading populations of S. alterniflora

Methods

Results

Conclusion