Seed mucilage improves seedling emergence of a sand desert shrub.

Xuejun Yang,Guangzheng Liu,Carol C Baskin,Zhenying Huang,Jerry M Baskin,Mari Moora

doi:10.1371/journal.pone.0034597

Xuejun Yang, Guangzheng Liu + Show 4 more

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https://doi.org/10.1371/journal.pone.0034597

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Abstract

The success of seedling establishment of desert plants is determined by seedling emergence response to an unpredictable precipitation regime. Sand burial is a crucial and frequent environmental stress that impacts seedling establishment on sand dunes. However, little is known about the ecological role of seed mucilage in seedling emergence in arid sandy environments. We hypothesized that seed mucilage enhances seedling emergence in a low precipitation regime and under conditions of sand burial. In a greenhouse experiment, two types of Artemisia sphaerocephala achenes (intact and demucilaged) were exposed to different combinations of burial depth (0, 5, 10, 20, 40 and 60 mm) and irrigation regimes (low, medium and high, which simulated the precipitation amount and frequency in May, June and July in the natural habitat, respectively). Seedling emergence increased with increasing irrigation. It was highest at 5 mm sand burial depth and ceased at burial depths greater than 20 mm in all irrigation regimes. Mucilage significantly enhanced seedling emergence at 0, 5 and 10 mm burial depths in low irrigation, at 0 and 5 mm burial depths in medium irrigation and at 0 and 10 mm burial depths in high irrigation. Seed mucilage also reduced seedling mortality at the shallow sand burial depths. Moreover, mucilage significantly affected seedling emergence time and quiescence and dormancy percentages. Our findings suggest that seed mucilage plays an ecologically important role in successful seedling establishment of A. sphaerocephala by improving seedling emergence and reducing seedling mortality in stressful habitats of the sandy desert environment.

Highlights

Seeds have special adaptations to different environments, and germination and subsequent seedling emergence may be altered by a wide range of environmental factors such as water, temperature, light, allelochemicals, mechanical interference and microbial pathogens [1,2]
The present study addressed the role of seed mucilage in seedling emergence in different precipitation regimes and sand burial conditions that A. sphaerocephala encounters in the natural sand dune habitat
Can mucilage enhance seedling emergence of A. sphaerocephala in different precipitation regime? We found that presence of mucilage increased seedling emergence (Figure 2) and this positive effect did not depend on water supply (Table 1)

Summary

Introduction

Seeds have special adaptations to different environments, and germination and subsequent seedling emergence may be altered by a wide range of environmental factors such as water, temperature, light, allelochemicals, mechanical interference and microbial pathogens [1,2]. Survival of new plants in arid environments is mainly determined by mechanisms that ensure germination and seedling development at the right time and in a suitable place [3]. Sand burial can prevent seed predation by surface foragers such as ants and beetles [16,17], provide more suitable microsites for germination and increase seedling survivorship because of instant access to moisture and insulation of the root system from high temperatures and desiccation [9]. Investigating the response of seedling emergence to sand burial is important for understanding the adaptation of plants to sand dune systems

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