Seed sojourn and fast viability loss constrain seedling production of a prominent riparian protection plant Salix variegata Franch.

Qiaoli Ayi,Yeyi Zhang,Hangang Niu,Shaohua Shi,Jianhui Liu,Bo Zeng,Feng Lin

doi:10.1038/srep37312

Abstract

Salix variegata Franch, a prominent plant applied in riparian shelter vegetation in Three Gorges reservoir region of China, produces many seeds every year but generates only a few or no seedlings. Whether the low seedling production of S. variegata is caused by seed sterility or by rapid loss of seed viability remains unknown. We investigated the sojourn time of mature seeds in capsules produced in early, mid, and late reproductive season and the germinability of mature seeds fresh or stored after different period of time. The sojourn time of seeds in capsules was 2.89, 3.95, and 4.72 days in early, mid, and late reproductive season, respectively. The maximal germination percentage of non-stored fresh seeds produced in early, mid, and late reproductive season was 93.33%, 78.67%, and 40%, respectively, which indicates mature seeds were not sterile. The longest viability-retaining time of seeds produced in early, mid, and late reproductive season was only 8, 16, 16 days, respectively, indicating that mature seeds of S. variegata lost viability very rapidly. Mature seeds possessed good viability, but their rapid viability loss caused the low seedling production and hampered the population growth of S. variegata in the riparian area of Three Gorges reservoir region.

Highlights

Salix variegata Franch, a prominent plant applied in riparian shelter vegetation in Three Gorges reservoir region of China, produces many seeds every year but generates only a few or no seedlings
We aim to answer the following questions: (1) Are seeds produced in S. variegata plants sterile? (2) Do S. variegata seeds retain their viability in a short time period and lose viability rapidly? (3) During the long reproductive season of S. variegata, do seeds produced at different time have different viability? The answers to the above-asked questions will reveal why S. variegata has low seedling production in the riparian shelter belt of Three Gorges reservoir, which is helpful to promote the riparian protection by S. variegata in Three Gorges reservoir region and the conservation of the species
Some studies have demonstrated that the weak population growth and spatial colonization of Phragmites australis, Ruppia maritima, Zostera marina can be attributed to the low viability of seeds[36,39,41]

Summary

Introduction

Salix variegata Franch, a prominent plant applied in riparian shelter vegetation in Three Gorges reservoir region of China, produces many seeds every year but generates only a few or no seedlings. Owing to the small quantity of seedlings produced, S. variegata population has been growing very slowly in riparian shelter belt, and is unable to fast expand S. variegata stand to a large area, which prevents S. variegata from playing its good role in the riparian protection of Three Gorges reservoir. The answers to the above-asked questions will reveal why S. variegata has low seedling production in the riparian shelter belt of Three Gorges reservoir, which is helpful to promote the riparian protection by S. variegata in Three Gorges reservoir region and the conservation of the species. The study on S. variegata, as a model species of genus Salix, will deepen our understanding of why many Salix species produce a lot of seeds but only obtain a small quantity of seedlings and why many Salix species have much smaller quantity of sexual descendants than their asexual descendants

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