State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
Ann Bot. 2012 Dec;110(8):1545-58. doi: 10.1093/aob/mcs205. Epub 2012 Sep 12.
Differences in dormancy and germination requirements have been documented in heteromorphic seeds of many species, but it is unknown how this difference contributes to maintenance and regeneration of populations. The primary aim of this study was to compare the seed bank dynamics, including dormancy cycling, of the two seed morphs (black and brown) of the cold desert halophyte Suaeda corniculata and, if differences were found, to determine their influence on regeneration of the species.
Seeds of the two seed morphs were buried, exhumed and tested monthly for 24 months over a range of temperatures and salinities, and germination recovery and viability were determined after exposure to salinity and water stress. Seedling emergence and dynamics of the soil seed bank were also investigated for the two morphs.
Black seeds had an annual dormancy/non-dormancy cycle, while brown seeds, which were non-dormant at maturity, remained non-dormant. Black seeds also exhibited an annual cycle in sensitivity of germination to salinity. Seedlings derived from black seeds emerged in July and August and those from brown seeds in May. Seedlings were recruited from 2·6 % of the black seeds and from 2·8 % of the brown seeds in the soil, and only 0·5 % and 0·4 % of the total number of black and brown seeds in the soil, respectively, gave rise to seedlings that survived to produce seeds. Salinity and water stress induced dormancy in black seeds and decreased viability of brown seeds. Brown seeds formed only a transient soil seed bank and black seeds a persistent seed bank.
The presence of a dormancy cycle in black but not in brown seeds of S. corniculata and differences in germination requirements of the two morphs cause them to differ in their germination dynamics. The study contributes to our limited knowledge of dormancy cycling and seed bank formation in species producing heteromorphic seeds.
许多物种的异型种子在休眠和萌发要求方面存在差异，但尚不清楚这种差异如何有助于种群的维持和再生。本研究的主要目的是比较冷荒漠盐生植物角果藜的两种种子形态（黑色和棕色）的种子库动态，包括休眠循环，如果发现差异，确定它们对物种再生的影响。
将两种种子形态的种子进行埋藏、挖掘，并在 24 个月的时间内，在一系列温度和盐度下每月进行测试，在暴露于盐度和水分胁迫后，测定种子的萌发恢复和活力。还对两种形态的幼苗出现和土壤种子库动态进行了研究。
黑色种子具有年度休眠/非休眠循环，而成熟时非休眠的棕色种子保持非休眠状态。黑色种子的萌发对盐度的敏感性也呈现出年度循环。来自黑色种子的幼苗于 7 月和 8 月出现，而来自棕色种子的幼苗于 5 月出现。幼苗从黑色种子中招募了 2.6%，从棕色种子中招募了 2.8%，而在土壤中，只有 0.5%和 0.4%的黑色和棕色种子总数分别产生了存活至产生种子的幼苗。盐度和水分胁迫会诱导黑色种子休眠，并降低棕色种子的活力。棕色种子只形成短暂的土壤种子库，而黑色种子则形成持久的种子库。
角果藜的黑色种子存在休眠循环，而棕色种子不存在休眠循环，两种形态的萌发要求存在差异，导致它们的萌发动态存在差异。本研究有助于我们对产生异型种子的物种休眠循环和种子库形成的有限认识。
