Do soil microbes and abrasion by soil particles influence persistence and loss of physical dormancy in seeds of tropical pioneers?
Do soil microbes and abrasion by soil particles influence persistence and loss of physical dormancy in seeds of tropical pioneers?
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DOI：
10.3389/fpls.2014.00799
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发表时间：
2014
影响因子：
5.6
通讯作者：
Dalling JW
中科院分区：
文献类型：
--
作者：
Zalamea PC;Sarmiento C;Arnold AE;Davis AS;Dalling JW
从土壤种子库（SSB）发芽是一个重要的决定因素，物种组成的热带森林的差距，种子持久性SSB允许树木招募，甚至几十年后扩散。形成持续性SSB的能力通常与物理休眠有关，其中种皮在传播时是不可渗透的。发芽文献经常推测，没有经验证据，休眠打破物理休眠种子是微生物作用和/或土壤颗粒磨损的结果。我们测试了微生物/土壤磨损假说，在四个广泛分布的新热带先锋树种（Apeiba membranacea，Luehea musannii，Ochroma musicale和Cochlospermum vitifolium）。种子被埋在五个常见的花园在巴拿马的一个低地热带森林，并在1，3，6和12个月后埋葬恢复。测量了种子渗透性、微生物感染、种皮厚度和发芽率。平行实验比较了新鲜和老化种子的发芽分数没有土壤接触，并在种子作为种子渗透性的函数。相反的微生物/土壤磨损假说的渗透性种子的比例，和种子感染的可培养的微生物，作为一个函数的埋葬时间下降。此外，在黑暗和干燥条件下储存2年的种子发芽率高于相同发芽条件下的新鲜种子。我们确定A. membranacea和O.在合点区或缺乏合点塞，而所有表面的不渗透的种子是完整的。我们的研究结果是不一致的微生物/土壤磨损假设的休眠损失，而是建议存在多个休眠表型，其中每个种子队列的一部分是分散在一个可渗透的状态和发芽立即，而不可渗透的种子部分占持久的SSB。因此，我们的结论是，在没有土壤磨损和微生物感染的情况下，土壤温度的波动足以打破热带先锋树种子的物理休眠。
Germination from the soil seed bank (SSB) is an important determinant of species composition in tropical forest gaps, with seed persistence in the SSB allowing trees to recruit even decades after dispersal. The capacity to form a persistent SSB is often associated with physical dormancy, where seed coats are impermeable at the time of dispersal. Germination literature often speculates, without empirical evidence, that dormancy-break in physically dormant seeds is the result of microbial action and/or abrasion by soil particles. We tested the microbial/soil abrasion hypothesis in four widely distributed neotropical pioneer tree species (Apeiba membranacea, Luehea seemannii, Ochroma pyramidale, and Cochlospermum vitifolium). Seeds were buried in five common gardens in a lowland tropical forest in Panama, and recovered at 1, 3, 6, and 12 months after burial. Seed permeability, microbial infection, seed coat thickness, and germination were measured. Parallel experiments compared the germination fraction of fresh and aged seeds without soil contact, and in seeds as a function of seed permeability. Contrary to the microbial/soil abrasion hypothesis the proportion of permeable seeds, and of seeds infected by cultivable microbes, decreased as a function of burial duration. Furthermore, seeds stored in dark and dry conditions for 2 years showed a higher proportion of seed germination than fresh seeds in identical germination conditions. We determined that permeable seeds of A. membranacea and O. pyramidale had cracks in the chalazal area or lacked the chalazal plug, whereas all surfaces of impermeable seeds were intact. Our results are inconsistent with the microbial/soil abrasion hypothesis of dormancy loss and instead suggest the existence of multiple dormancy phenotypes, where a fraction of each seed cohort is dispersed in a permeable state and germinates immediately, while the impermeable seed fraction accounts for the persistent SSB. Thus, we conclude that fluctuations in the soil temperature in the absence of soil abrasion and microbial infection are sufficient to break physical dormancy on seeds of tropical pioneer trees.
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影响因子：
1.4
作者：
Fornara, DA;Dalling, JW
通讯作者：
Dalling, JW
影响因子：
2.5
作者：
Davis, Adam S.;Schutte, Brian J.;Renner, Karen A.
通讯作者：
Renner, Karen A.
影响因子：
5.5
作者：
Dalling, JW;Muller-Landau, HC;Hubbell, SP
通讯作者：
Hubbell, SP
影响因子：
4.9
作者：
Bidartondo, Martin I.;Read, David J.
通讯作者：
Read, David J.
影响因子：
2.1
作者：
Baskin, JM;Baskin, CC
通讯作者：
Baskin, CC