Majority legumes in the temperate and arctic zones have water-impermeable seeds (physical dormancy, PY). However, various authors have reported that seeds of some Caragana species are water-permeable and thus non-dormant. We (1) tested seeds of 15 species of Caragana matured in the same site in 2014, 2016 and/or 2017 for presence of PY, (2) determined if dry storage decreased or increased the percentage of seeds with PY and (3) located the site on the seed coat of 11 species where water enters the seed. Sixty-three percent and 45% of the seeds of C. roborovskyi had PY in 2016 and 2017, respectively, but only 0–14% of the seeds of the other 14 species had PY. The palisade layer in the seed coat of water impermeable seeds had no cracks in it, whereas cracks were present in the palisade layer of water-permeable seeds. Year of collection and dry storage had significant effects on imbibition of two species (C. acanthophylla and C. roborovskyi). In two (C. acanthophylla and C. roborovskyi) of the 11 species tested, the hilum was the site of water entry into seeds (control seeds, not any dormant broken treatments), but for the other nine species tested water entered through all parts of the seed coat.

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Notes/Citation Information

Published in PeerJ, v. 7, e6870, p. 1-13.

© 2019 Chen et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.

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Funding Information

This study was supported by the National Key R&D Program of China (2017YFC0504603) and the National Natural Science Fund (31672473) and the Fundamental Research Funds for the Central Universities (lzujbky-2017-it12, lzujbky-2018-it12).

Related Content

The following information was supplied regarding data availability: The raw data are available in Datasets S1–S4.

Supplemental information for this article can be found online at https://doi.org/10.7717/peerj.6870#supplemental-information.

Mean monthly rainfall and mean monthly daily temperature at the seed collection site in 2014, 2016 and 2017. https://doi.org/10.7717/peerj.6870/supp-1

Permeability to water of seeds of 23 Caragana species Y, yes; N, no. https://doi.org/10.7717/peerj.6870/supp-2

The moisture content of fresh seeds of the 15 Cagagana species at Minqin in Gansu, China. https://doi.org/10.7717/peerj.6870/supp-3

The 1,000-seed mass of seeds of the 15 Cagagana species. https://doi.org/10.7717/peerj.6870/supp-4

The percentage of water-impermeable seeds of 15 Caragana species. https://doi.org/10.7717/peerj.6870/supp-5

Mean monthly rainfall and mean monthly daily temperature at the seed collection site. https://doi.org/10.7717/peerj.6870/supp-6

The moisture content of fresh seeds of the 15 Cagagana species. https://doi.org/10.7717/peerj.6870/supp-7

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Fig. S1

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Table S1

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Table S2

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Dataset S1

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Dataset S2

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Dataset S3

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Dataset S4